Methods and compositions for the biological control of plant pathogens

Abstract

The present disclosure provides methods and compositions for inhibiting or preventing the growth of a fungus, for treating or preventing fungal pathogen infections in plants and plant products or fungal plant diseases, for protecting crops and products harvested from plants from fungal pathogens, and for protecting harvested crops and agricultural food products from spoilage caused by fungal pathogens. The compositions employed in accordance with the present disclosure comprise tropone, or a derivative or salt thereof, wherein the derivative is a compound of Formula (I) as defined herein.

Description

METHODS AND COMPOSITIONS FOR THE BIOLOGICAL CONTROL OFPLANT PATHOGENSFIELD OF THE ART

[0001] The present disclosure relates generally to antifungal metabolites produced by microorganisms, such as Streptomyces species. More specifically the present disclosure relates to the use of tropone (2,4,6-cycloheptatrien-l-one) as an antifungal agent, in particular for the treatment or prevention of fungal pathogen infections on plants, plant parts and harvested produce such as fruits and seeds.BACKGROUND

[0002] Plant disease as a result of fungal pathogen infection represents a significant economic cost to modern agriculture. Current systems of agriculture often require one or a few crops or plant types to be grown over a large area. Such ecologically unbalanced systems are susceptible to disease. Plant fungal pathogens alone are responsible for losses in the order of billions of dollars globally to agricultural production. Key fungi responsible for food loss in the field or post-harvest include members of the Aspergillus, Botrytis, Fusarium, Penicillium, Phytophthora, Rhizoctonia, Sclerotinia, Verticillium, Zymoseptoria genera.

[0003] For example, soil / stubble-borne fungi cause diseases of wheat and canola that alone cost the Australian grain and oilseed industries in excess of $250 million annually. The incidence of some of these diseases is on the rise, including Fusarium crown rot of wheat and Sclerotinia Stem Rot of canola. Sclerotinia is one of the most devastating plant pathogens, causing stem rot disease on over 500 plant species and an increasing constraint to canola production. A global problem, Sclerotinia cost the world’s largest canola producer (Canada) an estimated US$600 million in just one year (2010). The fungal pathogen responsible for Rhizoctonia root and hypocotyl rots of canola also has a high potential for disease severity in Australia.

[0004] Fusarium graminearum, a member of the fungal phylum Ascomycota is a plant pathogen which causes fusarium head blight. This is a devastating disease on wheat and barley. The pathogen is responsible for billions of dollars in economic losses worldwideeach year and result in toxin production harmful to livestock and humans through contaminated food. Another member of Ascomycota is Fusarium pseudograminearum which causes crown rot of wheat. Crown rot of wheat is an important plant disease that without management can have serious detrimental effects on entire fields of wheat causing white heads which have no grains, leading to large yield losses.

[0005] Crop yield losses caused by fungal pathogens are compounded by the limited availability of effective control strategies and growing pesticide resistance. Plant breeding programs have had some success in producing more tolerant varieties to some diseases but none of these show effective disease resistance across multiple pathogens. In some cases, despite great efforts to find resistance genes, for example against the devastating pathogen F. pseudograminearum, no completely resistant variety is currently available. Furthermore, many pathogens can persist by surviving or growing in the soil, stubble or on the roots of summer weeds, and act as a source of infection in the following crop.

[0006] Contamination and spoilage of food at harvest or post-harvest, and of stored grain, is a critical point of food safety. Losses post-harvest have been estimated to be 20- 40% globally. By way of example, without treatment up to 90% of citrus fruit can be lost, currently citrus fruit rot rate is 10-30% relying on the application of synthetic fungicides. For many agricultural crops, e.g. fruit such as strawberries, there are currently no or limited postharvest fungicides available for use. The most common decaying agent is grey mould, caused by Botrytis cinerea, and currently management involves a range of time-consuming and intensive tasks that are to be undertaken throughout the production cycle.

[0007] In response to societal demands for alternatives to synthetic pesticides, biological control (biocontrol) agents are emerging as important, environment-friendly solutions for plant protection and harvested product protection. Many microorganisms are known to control various plant pathogens using multiple modes of activity, including the production of various specialised metabolites with potent biological activities. Despite advancements in genomic technologies that have enhanced our understanding of microbial metabolic potential, significant challenges remain in deciphering the identity of many active metabolites, thereby hampering the development of next-generation antifungal agents.SUMMARY OF THE DISCLOSURE

[0008] One aspect of the present disclosure provides a method for inhibiting or preventing the growth of a fungus, comprising exposing the fungus, or a surface or environs on which the fungus grows or is capable of growing to a compound selected from tropone and a derivative or salt thereof, wherein where the compound is a derivative of tropone the derivative is a compound of Formula (I) or a salt thereofwherein:R1and R2are independently selected from the group consisting of alkyl, alkenyl, alkynyl, alkoxy, carboxyl, carbamoyl, acyl, aryl, heteroaryl, amino, alkylamino, cycloalkyl, cycloalkenyl, cycloalkynyl, heterocyclyl, halogen, cyano, nitro, NCS, SCN, alkylcarbonyl, alkylthiocarbonyl, alkoxycarbonyl and aminocarbonyl; and n is 0, 1, 2, 3 or 4.

[0009] In a particular embodiment, the compound is tropone.

[0010] The compound may be administered to the fungus, or surface or environs on which the fungus grows or is capable of growing by fumigation. Typically, the compound is applied in the form of a composition comprising one or more carriers, diluents or adjuvants, optionally agriculturally and food safety acceptable carriers, diluents or adjuvants. The composition may be a fumigant composition.

[0011] In particular embodiments, the fungus is a pathogen, more particularly a plant pathogen, and the compound or composition is applied to soil or other plant germination, propagation or growth media in which the plant is grown or is to be grown, plant surrounds or to one or more plant parts. The plant part may comprise, for example, seed, roots, leaves, stems or a reproductive structure including flowers, fruits and nuts.

[0012] In particular embodiments, the pathogen is a pathogen of one or more commercially cultivated crops. The pathogen may belong, for example, to a genus selected from Alternaria, Ascochyta, Aspergillus, Botrytis, Colletotrichum, Fusarium, Gaeumannomyces, Gibberella, Leptosphaeria, Magnaporthe, Mycosphaerella, Penicillium,Pythium, Phytophthora, Rhizoctonia, Sclerotinia, Ustilago, Verticillium, and Zymoseptoria. In exemplary embodiments, the pathogen is a Penicillium, Verticillium, Fusarium, Sclerotinia, Rhizoctonia or Zymoseptoria.

[0013] In exemplary embodiments, the plant is selected from a crop plant, such as a cereal crop, oilseed crop, grain crop, horticultural crop, or a crop for fibre production or ornamentals.

[0014] Another aspect of the present disclosure provides a method for reducing susceptibility of a plant to a fungal infection, the method comprising applying to the plant or plant surrounds a compound selected from tropone and a derivative or salt thereof, wherein where the compound is a derivative of tropone the derivative is a compound of Formula (I) or a salt thereofwherein:R1and R2are independently selected from the group consisting of alkyl, alkenyl, alkynyl, alkoxy, carboxyl, carbamoyl, acyl, aryl, heteroaryl, amino, alkylamino, cycloalkyl, cycloalkenyl, cycloalkynyl, heterocyclyl, halogen, cyano, nitro, NCS, SCN, alkylcarbonyl, alkylthiocarbonyl, alkoxycarbonyl and aminocarbonyl; and n is 0, 1, 2, 3 or 4.

[0015] In a particular embodiment, the compound is tropone.

[0016] The compound may be administered to the plant or plant surrounds by fumigation. Typically the compound is applied in the form of a composition comprising one or more agriculturally acceptable carriers, diluents or adjuvants. The composition may be a fumigant composition.

[0017] In particular embodiments, the compound or composition is applied to soil or other plant germination, propagation or growth media in which the plant is grown or is to be grown or to one or more plant parts. The plant part may comprise, for example, seed, roots, leaves, stems or a reproductive structure including flowers, fruits and nuts.

[0018] The plant, plant part or plant surrounds may or may not display visible signs of fungal pathogen infection (fungal contamination) prior to treatment.

[0019] In particular embodiments, the pathogen is a pathogen of one or more commercially cultivated crops. The pathogen may belong, for example, to a genus selected from Alternaria, Ascochyta, Aspergillus, Botrytis, Colletotrichum, Fusarium, Gaeumannomyces, Gibberella, Leptosphaeria, Magnaporthe, Mycosphaerella, Penicillium, Pythium, Phytophthora, Rhizoctonia, Sclerotinia, Ustilago, Verticillium, and Zymoseptoria. In exemplary embodiments, the pathogen is a Verticillium, Penicillium, Fusarium, Sclerotinia, Rhizoctonia or Zymoseptoria.

[0020] In exemplary embodiments, the plant is selected from a crop plant, such as a cereal crop, oilseed crop, grain crop, horticultural crop, or a crop for fibre production or ornamentals.

[0021] Another aspect of the present disclosure provides a method for treating or preventing a fungal pathogen infection of a plant, or for treating or preventing a fungal plant disease, the method comprising applying to the plant or plant surrounds a compound selected from tropone and a derivative or salt thereof, wherein where the compound is a derivative of tropone the derivative is a compound of Formula (I) or a salt thereofwherein:R1and R2are independently selected from the group consisting of alkyl, alkenyl, alkynyl, alkoxy, carboxyl, carbamoyl, acyl, aryl, heteroaryl, amino, alkylamino, cycloalkyl, cycloalkenyl, cycloalkynyl, heterocyclyl, halogen, cyano, nitro, NCS, SCN, alkylcarbonyl, alkylthiocarbonyl, alkoxycarbonyl and aminocarbonyl; and n is 0, 1, 2, 3 or 4.

[0022] In a particular embodiment, the compound is tropone.

[0023] The compound may be administered to the plant or plant surrounds by fumigation. Typically the compound is applied in the form of a composition comprising oneor more agriculturally acceptable carriers, diluents or adjuvants. The composition may be a fumigant composition.

[0024] In particular embodiments, the compound or composition is applied to soil or other plant germination, propagation or growth media in which the plant is grown or is to be grown or to one or more plant parts. The plant part may comprise, for example, seed, roots, leaves, stems or a reproductive structure including flowers, fruits and nuts.

[0025] The plant, plant part or plant surrounds may or may not display visible signs of fungal pathogen infection (fungal contamination) prior to treatment.

[0026] In particular embodiments, the pathogen is a pathogen of one or more commercially cultivated crops. The pathogen may belong, for example, to a genus selected from Alternaria, Ascochyta, Aspergillus, Botrytis, Colletotrichum, Fusarium, Gaeumannomyces, Gibberella, Leptosphaeria, Magnaporthe, Mycosphaerella, Penicillium, Pythium, Phytophthora, Rhizoctonia, Sclerotinia, Ustilago, Verticillium, and Zymoseptoria. In exemplary embodiments, the pathogen is a Penicillium, Verticillium, Fusarium, Sclerotinia, Rhizoctonia or Zymoseptoria.

[0027] In exemplary embodiments, the plant is selected from a crop plant, such as a cereal crop, oilseed crop, grain crop, horticultural crop, or a crop for fibre production or ornamentals.

[0028] Another aspect of the disclosure provides a method for protecting a crop or product harvested from a plant from a fungal pathogen, comprising directly or indirectly applying to the crop or product a compound selected from tropone and a derivative or salt thereof, wherein where the compound is a derivative of tropone the derivative is a compound of Formula (I) or a salt thereofwherein:R1and R2are independently selected from the group consisting of alkyl, alkenyl, alkynyl, alkoxy, carboxyl, carbamoyl, acyl, aryl, heteroaryl, amino, alkylamino, cycloalkyl,cycloalkenyl, cycloalkynyl, heterocyclyl, halogen, cyano, nitro, NCS, SCN, alkylcarbonyl, alkylthiocarbonyl, alkoxycarbonyl and aminocarbonyl; and n is 0, 1, 2, 3 or 4.

[0029] In a particular embodiment, the compound is tropone.

[0030] The compound may be administered to the crop or product by fumigation. Typically the compound is applied in the form of a composition comprising one or more agriculturally acceptable carriers, diluents or adjuvants. The composition may be a fumigant composition.

[0031] The crop or product may comprise for example, fruits, vegetables, grain, cereals, nuts, oilseeds, or flowers. The crop or product may or may not display visible signs of fungal pathogen infection (fungal contamination) prior to treatment.

[0032] The method may protect harvested crops and agricultural food products from spoilage caused by fungal pathogens and / or prolong the shelf life of harvested crops and agricultural food products.

[0033] In exemplary embodiments, the fungal pathogen is selected from Aspergillus, Colletotrichum, Penicillium, Botrytis and Sclerotinia.

[0034] In particular embodiments, the compound or composition is deployed via fumigation, for instance in a post-harvest facility. The post-harvest facility may comprise, for example a facility in which harvested crop or agricultural food product is sorted, cleaned, stored, packed, transported, processed or otherwise handled. The fumigation may be delivered using material impregnated or coated or otherwise treated with the composition of tropone or derivative thereof.

[0035] The application of the compound or composition may prevent damage to the crop or product from post-harvest fungal disease caused by the fungal pathogen.

[0036] Accordingly, another aspect of the present disclosure provides a method for protecting a harvested crop or agricultural food product from spoilage caused by a fungal pathogen, comprising directly or indirectly applying to the harvested crop or agricultural food product a compound selected from tropone and a derivative or salt thereof, wherein where the compound is a derivative of tropone the derivative is a compound of Formula (I) or a salt thereofwherein:R1and R2are independently selected from the group consisting of alkyl, alkenyl, alkynyl, alkoxy, carboxyl, carbamoyl, acyl, aryl, heteroaryl, amino, alkylamino, cycloalkyl, cycloalkenyl, cycloalkynyl, heterocyclyl, halogen, cyano, nitro, NCS, SCN, alkylcarbonyl, alkylthiocarbonyl, alkoxycarbonyl and aminocarbonyl; and n is 0, 1, 2, 3 or 4.

[0037] In a particular embodiment, the compound is tropone.

[0038] The compound may be administered to the harvested crop or agricultural food product by fumigation. Typically the compound is applied in the form of a composition comprising one or more agriculturally acceptable carriers, diluents or adjuvants. The composition may be a fumigant composition.

[0039] The crop or agricultural food product may comprise for example, fruits, vegetables, grain, cereals, nuts, oilseeds, or flowers, or a product containing fruits, vegetables, grain, cereals, nuts, oilseeds, or flowers. The crop or agricultural food product may or may not display visible signs of fungal pathogen infection (fungal contamination) prior to treatment.

[0040] Another aspect of the present disclosure provides the use of a compound selected from tropone and a derivative or salt thereof, in the manufacture of a composition for inhibiting or preventing the growth of a fungus, treating or preventing a fungal pathogen infection of a plant, for treating or preventing a fungal plant disease, for protecting a crop or product harvested from a plant from a fungal pathogen, or for protecting a harvested crop or agricultural food product from spoilage caused by a fungal pathogen, wherein where the compound is a derivative of tropone the derivative is a compound of Formula (I) or a salt thereofwherein:R1and R2are independently selected from the group consisting of alkyl, alkenyl, alkynyl, alkoxy, carboxyl, carbamoyl, acyl, aryl, heteroaryl, amino, alkylamino, cycloalkyl, cycloalkenyl, cycloalkynyl, heterocyclyl, halogen, cyano, nitro, NCS, SCN, alkylcarbonyl, alkylthiocarbonyl, alkoxycarbonyl and aminocarbonyl; and n is 0, 1, 2, 3 or 4.

[0041] In a particular embodiment, the compound is tropone.

[0042] Another aspect of the present disclosure provides the use of a compound selected from tropone and a derivative or salt thereof, as a fumigant for the inhibition or prevention of growth of a fungus, for the treatment or prevention of a fungal pathogen infection of a plant, for the treatment or prevention of a fungal plant disease, for the protection of a crop or product harvested from a plant from a fungal pathogen, or for the protection of a harvested crop or agricultural food product from spoilage caused by a fungal pathogen, wherein where the compound is a derivative of tropone the derivative is a compound of Formula (I) or a salt thereofwherein:R1and R2are independently selected from the group consisting of alkyl, alkenyl, alkynyl, alkoxy, carboxyl, carbamoyl, acyl, aryl, heteroaryl, amino, alkylamino, cycloalkyl, cycloalkenyl, cycloalkynyl, heterocyclyl, halogen, cyano, nitro, NCS, SCN, alkylcarbonyl, alkylthiocarbonyl, alkoxycarbonyl and aminocarbonyl; and n is 0, 1, 2, 3 or 4.

[0043] In a particular embodiment, the compound is tropone.

[0044] Another aspect of the present disclosure provides an antifungal composition comprising a compound selected from tropone and a derivative or salt thereof, optionally in combination with one or more one or more suitable carriers, diluents or adjuvants, optionally agriculturally acceptable carriers, diluents or adjuvants,wherein where the compound is a derivative of tropone the derivative is a compound of Formula (I) or a salt thereofwherein:R1and R2are independently selected from the group consisting of alkyl, alkenyl, alkynyl, alkoxy, carboxyl, carbamoyl, acyl, aryl, heteroaryl, amino, alkylamino, cycloalkyl, cycloalkenyl, cycloalkynyl, heterocyclyl, halogen, cyano, nitro, NCS, SCN, alkylcarbonyl, alkylthiocarbonyl, alkoxycarbonyl and aminocarbonyl; and n is 0, 1, 2, 3 or 4.

[0045] In a particular embodiment, the compound is tropone.

[0046] In an embodiment, the composition is used to treat or prevent an infection or disease caused by, or associated with, a fungal plant pathogen. In an embodiment, the composition is used to reduce the susceptibility of a plant to a fungal plant pathogen infection. In an embodiment, the composition is preferably applied to a plant, plant part, or plant surrounds to treat or prevent disease caused by, or associated with a fungal plant pathogen, or to reduce the susceptibility of a plant to a fungal pathogen infection.

[0047] Another aspect of the present disclosure provides a fumigant composition comprising a compound selected from tropone and a derivative or salt thereof, optionally in combination with one or more one or more suitable carriers, diluents or adjuvants, optionally agriculturally acceptable carriers, diluents or adjuvants, wherein where the compound is a derivative of tropone the derivative is a compound of Formula (I) or a salt thereofwherein:R1and R2are independently selected from the group consisting of alkyl, alkenyl, alkynyl, alkoxy, carboxyl, carbamoyl, acyl, aryl, heteroaryl, amino, alkylamino, cycloalkyl,cycloalkenyl, cycloalkynyl, heterocyclyl, halogen, cyano, nitro, NCS, SCN, alkylcarbonyl, alkylthiocarbonyl, alkoxycarbonyl and aminocarbonyl; and n is 0, 1, 2, 3 or 4.

[0048] In a particular embodiment, the compound is tropone.

[0049] The composition may be a gaseous, vapourised or liquid, e.g. aqueous, composition. Typically the composition is to be applied to a plant, plant part, plant surrounds, crop or agricultural product to inhibit or prevent growth of a fungus, treat or prevent fungal pathogen infection or fungal plant disease, protect a crop or product harvested from a plant from a fungal pathogen, or protect a harvested crop or agricultural food product from spoilage caused by a fungal pathogen.

[0050] The following disclosure relates to all the above aspects and embodiments.BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Embodiments of the invention are described herein, by way of non-limiting example only, with reference to the following figures.

[0052] Figure 1. Spent media from MH71 fermentation inhibits fungal growth during the stationary growth phase. (A) Relative glucose concentration measured from three liquid cultures, with error bars denoting standard deviation. (B) Growth inhibition of V. dahliae after 15-hours incubation with 2-fold dilutions of MH71 spent media collected at 24, 48, 72, 96, 120, 144 and 168 hours of fermentation in YME medium and filtered (0.2 pm). Each heatmap square represents the average fungal growth inhibition (%) from triplicate samples, with time points in columns and concentration of spent media on each row. Average IC50 values for each time points are shown above. (C) Fungal growth inhibition of the GFP- labelled V. dahliae (Vd71171-eGFP) was calculated based on GFP expression using fluorescence microscopy images (10X). Images of the inhibitory effect in spore germination and mycelial extension after incubation with spent media collected at 72 h (1), 96 (2), 120 h (3), 144 h (4) and 168 h (5), at 3.125% (1-2), and 0.781 % (3-5) concentrations, compared to negative control (no spent media added), and blank (no media or V. dahliae added). Images are representative wells from triplicate experiments.

[0053] Figure 2. Split plate bioassay shows effects of MH71 volatile emissions on V. dahliae growth. Cultures of MH71 were grown on the bottom half of petri dishes in (B)(i.e. bottom row) such that the opposing half of the dish was only influenced by volatile emissions. Dishes in (A) (i.e. top row) did not contain cultures of MH71. After 7 days, in each dish sterile filter paper inoculated with V. dahliae 71171-eGFP was applied to the top half of each plate (in (A) and (B)), and growth was tracked and photographed over 2 days.

[0054] Figure 3. Headspace GCMS metabolomics identified volatile organic compounds unique to each culture timepoint. (A) Heatmap dendrogram displaying all volatile organic compounds produced at 72 and 96 hours fermentation of MH71. Colour (shading) corresponds to the z-score normalised to each metabolite. Metabolite names correspond to matches within NIST compound library. Tropone is shown in bold text, indicating a confirmed identification. (B) Tropone transient abundance. Boxplot displaying extracted ion counts of base peak corresponding to tropone in cultures. Diamonds correspond to mean value, while central bars display the median.

[0055] Figure 4. Gas chromatograph - electron impact mass spectra of experimentally derived tropone and pure standard. The fragmentation pattern, retention time (RT), retention index (RI) of the Streptomyces-denved tropone (A) match that of commercially sourced tropone (B). Both samples were applied to gas chromatography mass spectrometer (GCMS) using solid-phase microextraction from the headspace of GCMS vials.

[0056] Figure 5. Assay comparing treated and untreated growth of Verticillium dahliae over 72 hours. Cultures were exposed to either nothing (control), or exposed to the indicated volume of tropone. Shown are representative plates from triplicate treatments.

[0057] Figure 6. Tropone inhibits a range of plant pathogenic fungi. Petri dishes were inoculated with Fusarium oxysporum medicaginis, Rhizoctonia solani AG-2, V. dahliae or Zymoseptoria tritici and tropone (10 pl, 20 pl or 40 pl) pipetted onto filter paper attached to the upper internal surface of the petri dish. The petri dish was sealed and fungal growth monitored for a number of days, depending on the growth habit of the fungus. Growth of the fungus in the presence of tropone was determined as a percentage relative to controls (no tropone). For a specific fungus, the absence of a bar in the graph for a given amount of tropone indicates that that amount of tropone was not tested against that fungus. Left to right, F. oxysporum medicaginis (20 pl and 40 pl tropone), R. solani AG-2 (20 pl and 40 pl tropone), V. dahliae (10 pl and 40 pl tropone) and Z. tritici (40 pl tropone). Data shown are the results of triplicate tests (including controls).

[0058] Figure 7. Selected plates were photographed to illustrate colony morphology and growth rate changes due to tropone exposure. Plates shown were grown for 72 hours, and those treated with tropone were treated with 40 or 20 pl of tropone as indicated.

[0059] Figure 8. Tropone inhibition of a range of plant pathogenic fungi after 72 hours of incubation. Neat tropone (20 ul) was pipetted onto filter paper attached to the upper internal surface of petri dishes. Each petri dish was sealed, and growth monitored. Data shown is the result of triplicate tests (including comparator control).

[0060] Figure 9. Exemplary photographs of plates used in the bioassay, showing colony morphology and growth rate reduction due to tropone exposure after 72 hours (3 days) (A) and 7 days (B). Panel (C) shows the exemplary plates for Penicillium citrinum for 7 days (right) and 14 days (left) was monitored for up to 14 days.

[0061] Figure 10. Tropone inhibits P. citrinum growth. Petri dishes were inoculated with P. citrinum, and tropone (20 ul) pipetted onto filter paper attached to the upper internal surface of petri dishes. Each petri dish was sealed, and growth monitored over 14 days. Data shown is the result of triplicate tests (including comparator control).

[0062] Figure 11. Fungal hyphae contamination (% relative to total fruit area) in strawberries and avocado following treatment with 20 pl tropone. Data shown are the results of triplicate tests for strawberry and duplicate tests for avocado (including controls).

[0063] Figure 12. Fungal contamination of wheat seed, following treatment with 20 pl tropone, or 50 pl tropone, or no tropone (control). Data shown are the results of triplicate tests.

[0064] Figure 13. Viability of Verticillium-GFP spores in the presence of tropone or fungicide controls. (A), shows GFP-fluorescence signal in each well containing Verticillium-G¥P spores treated with tropone, fungicide controls, untreated (+ve control) or water only (-ve control, no fungal spores added). The GFP signal is white false coloured. Where spores are viable, a GFP signal is detected. (B), shows quantified GFP signal per well. Zero meaning no signal or dead cells. Wells with partially dead or dying cells have less GFP signal than the positive controls. Similar data was obtained in a replicate plate.

[0065] Figure 14. Representative GFP and brightfield images from treated Verticillium-G¥P spores illustrating fungicidal activity.DETAILED DESCRIPTION

[0066] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the disclosure belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present disclosure, typical methods and materials are described.

[0067] The articles “a” and “an” are used herein to refer to one or to more than one (z.e., to at least one) of the grammatical object of the article, unless the context clearly dictates otherwise. By way of example, “a strain” can mean one strain or more than one strain.

[0068] In the context of this specification, the term "about," is understood to refer to a range of numbers that a person of skill in the art would consider equivalent to the recited value in the context of achieving the same function or result.

[0069] Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

[0070] As described and exemplified herein, the present inventors investigated global transcription patterns of biosynthetic gene cluster expression and the secreted metabolome of Streptomyces sp. MH71 (National Measurement Institute of Australia Accession No. VI 7 / 004100; see WO 2019 / 046909, the disclosure of which is incorporated herein by reference) during the exponential and stationary phases, with the latter phase coinciding with the surge of antifungal activity against the cotton pathogen Verticillium dahliae. This involved assembling a high-quality genome of MH71, followed by genome mining to uncover a repertoire of secondary metabolites. RNA sequencing was employed to track the differential expression of biosynthetic gene clusters, and detection of the resulting metabolic products was done using a complementary mass spectrometry approach, including the analysis of soluble metabolites by liquid chromatography-mass spectrometry and the characterization of volatile metabolites (volatilome) using gas chromatography-mass spectrometry.

[0071] The inventors used a multi-omic approach to identify antifungal compounds produced by Streptomyces sp. MH71. This approach encompassed genome assembly and mining, as well as comparative transcriptomic and metabolic analyses. The inventors found that the antifungal activity of MH71 is associated with distinct changes at the transcript and metabolite levels, which are linked to the bacterial growth cycle. Moreover, the inventors surprisingly found that tropone (2,4,6-cycloheptatrien-l-one), produced by MH71 during the stationary phase, exhibits antifungal activity against a range of fungal phytopathogens.Accordingly, in one aspect the present disclosure provides a a method for inhibiting or preventing the growth of a fungus, comprising exposing the fungus, or a surface or environs on which the fungus grows or is capable of growing to a compound selected from tropone and a derivative or salt thereof, wherein where the compound is a derivative of tropone the derivative is a compound of Formula (I) or a salt thereofwherein:R1and R2are independently selected from the group consisting of alkyl, alkenyl, alkynyl, alkoxy, carboxyl, carbamoyl, acyl, aryl, heteroaryl, amino, alkylamino, cycloalkyl, cycloalkenyl, cycloalkynyl, heterocyclyl, halogen, cyano, nitro, NCS, SCN, alkylcarbonyl, alkylthiocarbonyl, alkoxycarbonyl and aminocarbonyl; and n is 0, 1, 2, 3 or 4.

[0072] In particular embodiments, the compound is tropone.

[0073] In particular embodiments, the fungus is a pathogen, more particularly a plant pathogen.Accordingly, also provided herein is a method for reducing susceptibility of a plant to a fungal infection, the method comprising applying to the plant or plant surrounds a compound selected from tropone and a derivative or salt thereof, wherein where the compound is a derivative of tropone the derivative is a compound of Formula (I) or a salt thereofwherein:R1and R2are independently selected from the group consisting of alkyl, alkenyl, alkynyl, alkoxy, carboxyl, carbamoyl, acyl, aryl, heteroaryl, amino, alkylamino, cycloalkyl, cycloalkenyl, cycloalkynyl, heterocyclyl, halogen, cyano, nitro, NCS, SCN, alkylcarbonyl, alkylthiocarbonyl, alkoxycarbonyl and aminocarbonyl; and n is 0, 1, 2, 3 or 4.A further aspect provides a method for treating or preventing a fungal pathogen infection of a plant, or for treating or preventing a fungal plant disease, the method comprising applying to the plant or plant surrounds a compound selected from tropone and a derivative or salt thereof, wherein where the compound is a derivative of tropone the derivative is a compound of Formula (I) or a salt thereofwherein:R1and R2are independently selected from the group consisting of alkyl, alkenyl, alkynyl, alkoxy, carboxyl, carbamoyl, acyl, aryl, heteroaryl, amino, alkylamino, cycloalkyl, cycloalkenyl, cycloalkynyl, heterocyclyl, halogen, cyano, nitro, NCS, SCN, alkylcarbonyl, alkylthiocarbonyl, alkoxycarbonyl and aminocarbonyl; and n is 0, 1, 2, 3 or 4.

[0074] As used herein, the term "alkyl" as a group or part of a group refers to a straight or branched aliphatic hydrocarbon group, such as a C1-C24 alkyl, a C1-C12 alkyl, more preferably a C1-C10 alkyl, most preferably Ci-Ce unless otherwise noted. Examples of suitable straight and branched Ci-Ce alkyl substituents include methyl, ethyl, n-propyl, 2- propyl, n-butyl, sec-butyl, t-butyl, hexyl, and the like.

[0075] As used herein, the term "alkenyl" as a group or part of a group denotes an aliphatic hydrocarbon group containing at least one carbon-carbon double bond and whichmay be straight or branched preferably having 2-12 carbon atoms, more preferably 2-10 carbon atoms, most preferably 2-6 carbon atoms, in the normal chain. The group may contain a plurality of double bonds in the normal chain and the orientation about each is independently E or Z. Exemplary alkenyl groups include, but are not limited to, ethenyl, propenyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl and nonenyl.

[0076] As used herein, the term "alkynyl” as a group or part of a group means an aliphatic hydrocarbon group containing a carbon-carbon triple bond and which may be straight or branched preferably having from 2-12 carbon atoms, more preferably 2-10 carbon atoms, more preferably 2-6 carbon atoms in the normal chain. Exemplary structures include, but are not limited to, ethynyl and propynyl.

[0077] As used herein, the term “alkoxy” as a group or part of a group refers to an alkyl radical attached via an oxygen atom. Examples of alkoxy groups include (Ci-Ce)- alkoxy, such as methoxy, ethoxy, propoxy, 1 -methylethoxy, butoxy, 1 -methylpropoxy, 2- methylpropoxy and 1,1 -dimethylethoxy.

[0078] As used herein, the term “carboxyl” as a group or part of a group refers to the radical represented by -C(=O)OH and derived from a carboxylic acid.

[0079] As used herein, the term “carbamoyl” as a group or part of a group refers to the radical represented by -C(=O)NH2 and may also be known as an amido group.

[0080] As used herein, the term “acyl” as a group or part of a group refers to a group having a carbon-oxygen double bond, i.e. -C(=O)-. Examples of acyl groups include acetyl, benzoyl

[0081] As used herein, the term "aryl" as a group or part of a group denotes (i) an optionally substituted monocyclic, or fused polycyclic, aromatic carbocycle (ring structure having ring atoms that are all carbon) preferably having from 5 to 12 atoms per ring. Examples of aryl groups include phenyl, naphthyl, and the like; an example of a fused polycyclic aryl group is a partially saturated bicyclic aromatic carbocyclic moiety in which a phenyl and a C5-7 cycloalkyl or C5-7 cycloalkenyl group are fused together to form a cyclic structure, such as tetrahydronaphthyl, indenyl or indanyl. Typically an aryl group is a Ce- Cis aryl group.

[0082] As used herein, the term “heteroaryl” as a group or part of a group refers to an aryl group that contains one or more heteroatoms.

[0083] As used herein, the term “heteroatom” refers to a nitrogen (N), oxygen (O), sulfur (S), phosphorus (P), boron (B) or silicon (Si) atom.

[0084] As used herein, the term “amino” as a group or part of a group refers to a nitrogen atom to which two hydrogen atoms are attached. Amino groups may be attached to other groups, such as alkyl groups to form aminoalkyl groups, cycloalkyl groups to form aminocycloalkyl groups, and the like.

[0085] As used herein, the term "cycloalkyl" refers to a saturated monocyclic or fused or spiro polycyclic carbocycle, preferably containing from 3 to 9 carbons per ring, such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl and the like, unless otherwise specified. It includes monocyclic systems such as cyclopropyl and cyclohexyl, bicyclic systems such as decalin, and polycyclic systems such as adamantane. A cycloalkyl group typically is a C3-C9 cycloalkyl group.

[0086] As used herein, the term “cycloalkenyl” refers to a partially unsaturated carbocycle group that contains at least one alkenyl functionality, i.e. having a carbon-carbon double bond between two adjacent carbon atoms in the carbocycle. Examples of cycloalkenyl groups include 1-cyclobutenyl, 2-cyclobutenyl, 1 -cyclopentenyl, 2- cyclopentenyl, 3 -cyclopentenyl, or 1 -cyclohexenyl, 2-cyclohexenyl, 3 -cyclohexenyl, 1,3- cyclohexadienyl or 1,4-cyclohexadienyl.

[0087] As used herein, the term “cycloalkynyl” refers to a partially unsaturated carbocycle group that contains at least one alkynyl functionality, i.e. having a carbon-carbon triple bond between two adjacent carbon atoms in the carbocycle.

[0088] As used herein, the term “heterocyclyl” refers to a carbocyclic ring system in which one or more carbon atoms in the carbocycle is replaced with one or more heteroatoms, where each heteroatom is selected independently from N, O, S, P, B and Si. A heterocyclic group may be saturated, unsaturated or heteroaromatic. Examples of heterocyclyl groups include piperidinyl, piperazinyl, morpholinyl, thiomorpholinyl, dihydropyranyl, tetrahydropyranyl, dioxanyl, pyrrolinyl, pyrrolidinyl, imidazolinyl, imidazolidinyl, thiazolidinyl, oxazolidinyl, dioxolanyl, dioxolyl, pyrazolidinyl, tetrahydrofuranyl, dihydrofuranyl, oxetanyl, oxiranyl, azetidinyl, aziridinyl, oxazetidinyl, oxaziridinyl,oxazepanyl, oxazinanyl, azepanyl, oxopyrrolidinyl, dioxopyrrolidinyl, oxomorpholinyl, oxopiperazinyl and oxepanyl.

[0089] As used herein, the term “halogen” refers to a chlorine, fluorine, bromine or iodine group.

[0090] As used herein, the term “cyano” refers to a nitrile group or a group containing a carbon-nitrogen triple bond.

[0091] As used herein, the term “nitro” refers to an -NO2 group.

[0092] As used herein, the term “alkylcarbonyl” as a group or part of a group refers to a straight-chain or branched alkyl-C(=O) or acyl group, such as methylcarbonyl, ethyl carbonyl, n-propylcarbonyl, isopropylcarbonyl, s-butyl carbonyl and t-butyl carbonyl. Preference is also given to alkylcarbonyls having 1 to 4 carbon atoms.

[0093] As used herein, the term “alkylthiocarbonyl” as a group or part of a group refers to a straight-chain or branched alkyl-C(=S) group,

[0094] As used herein, the term “alkoxycarbonyl” as a group or part of a group refers to a straight-chain or branched alkoxy group that is attached to a carbonyl (i.e. acyl) group. Examples of such groups include methoxycarbonyl, ethoxycarbonyl, n-propoxycarbonyl, isopropoxycarbonyl, s-butoxy carbonyl and t-butoxy carbonyl.

[0095] As used herein, the term “aminocarbonyl” as a group or part of a group refers to a straight-chain or branched group with an amino group attached to a carbonyl (i.e. acyl group). Examples of such groups include an A-methylaminocarbonyl, N- ethylaminocarbonyl, A-(n-propylamino)carbonyl, A-(isopropylamino)carbonyl and A-(s- butylamino)carbonyl.

[0096] As used herein, the term “salt” refers to an ionic compound comprising tropone or the compound of Formula (I) where the desired activity of the compound itself is retained. The term may be used to refer to acid addition salts or base addition salts. Suitable acid addition salts of compounds of Formula (I) may be prepared from an inorganic acid or from an organic acid. Examples of such inorganic acids are hydrochloric acid, sulfuric acid, phosphoric acid, methane sulfonic acid, camphor sulfonic acid, oxalic acid, maleic acid, succinic acid, citric acid, formic acid, hydrobromic acid, benzoic acid, tartaric acid, fumaric acid, salicylic acid, mandelic acid, and carbonic acid. Appropriate organic acids may beselected from aliphatic, cycloaliphatic, aromatic, heterocyclic carboxylic and sulfonic classes of organic acids, examples of which are formic, acetic, propionic, succinic, glycolic, gluconic, lactic, malic, tartaric, citric, fumaric, maleic, alkyl sulfonic and arylsulfonic acids. Pharmaceutically acceptable salts also include those in which the main compound functions as an acid and is reacted with an appropriate base to form, e.g., sodium, potassium, calcium, magnesium, ammonium, and choline salts. Those skilled in the art will further recognize that acid addition salts may be prepared by reaction of a compound with the appropriate inorganic or organic acid via any of a number of known methods. Alternatively, alkali and alkaline earth metal salts can be prepared by reacting a compound with the appropriate base via a variety of known methods. The following are further examples of acid salts that can be obtained by reaction with inorganic or organic acids: acetates, adipates, alginates, citrates, aspartates, benzoates, benzenesulfonates, bisulfates, butyrates, camphorates, digluconates, cyclopentanepropionates, dodecyl sulfates, ethanesulfonates, glucoheptanoates, glycerophosphates, hemisulfates, heptanoates, hexanoates, fumarates, hydrobromides, hydroiodides, 2-hydroxy-ethanesulfonates, lactates, maleates, methanesulfonates, nicotinates, 2-naphthalenesulfonates, oxalates, palmoates, pectinates, persulfates, 3- phenylpropionates, picrates, pivalates, propionates, succinates, tartrates, thiocyanates, tosylates, mesylates and undecanoates.

[0097] In particular embodiments in accordance with the present disclosure, the compound is tropone. Tropone (2,4,6-cycloheptatrien-l-one) has the structure:

[0098] Within the chemical family of troponoids, tropones and tropolones differ in the presence of a hydroxy group at the alpha carbon (relative to the keto moiety). This difference is crucial in understanding the biological properties of these molecules as it provides a putative metallophore / ionophore mode of action for the tropolones (see, e.g. Moffat et al., 2024). Tropone does not contain this hydroxy group, and therefore has no theorised metal binding ability. As described herein, the present inventors have identified that tropone itself possesses antifungal and fungicidal activity offering new possibilities for its use as a fogging or fumigant for control of food deterioration relating to fungal disease. The skilled person will recognise and appreciate that compounds possessing a hydroxy groupat the alpha carbon (relative to the keto moiety) are excluded from the scope of the present disclosure.

[0099] The tropone may be obtained or derived from any suitable source. For example the tropone may be synthetically produced and may be obtained commercially. Alternatively, the tropone may be obtained from the culture or fermentation of a suitable cell producing tropone. For example, the tropone may be obtained as a metabolite from the culture or fermentation of a Streptomycete. The Streptomycete may be Streptomyces anlimycoliciis. optionally Streptomyces strain MH71 (deposited as NMI Accession No. VI 7 / 004100).

[0100] Accordingly, the tropone may be present in and applied in accordance with the present disclosure in the form of a cell free filtrate derived from a Streptomyces microorganism culture. A cell free filtrate may be prepared from a Streptomyces culture using one or more of methods well known to a person skilled in the art. For example the Streptomyces may be grown to stationary phase, optionally representing at least or about 78 hours, 84 hours, 90 hours or 96 hours of fermentation. Cell-free filtrate can be obtained from said culture by filtration through any suitable filter means to separate cell-free media from cells, as will be known to those skilled in the art. The presence of tropone in cell-free filtrate can be determined by any suitable means known to those skilled in the art, including for example mass spectrometry such as liquid chromatography mass spectrometry and gas chromatography mass spectrometry.

[0101] As used herein the term "applied", "applying" or "application" when used in relation to application of a compound or composition as described herein to a surface, environs, plant, plant part or plant surrounds will be understood to encompass "contacting" the surface, environs, plant, plant part or plant surrounds with the compound or composition, as well as to inoculating a plant or plant part with the compound or composition. “Applying” a compound or composition of the invention to a harvested product (i.e. a harvested crop or other agricultural food product) encompasses direct and indirect application. Indirect application includes application, e.g. by spraying, impregnation or fumigation, to a container or facility in which the harvested product may be sorted, cleaned, stored, packed, transported, processed or otherwise handled. Indirect application can also include protecting harvested product from fungal infection by inhibition or prevention of transmission of a fungus or fungal infection from surrounding crop or product by application of the compound or composition to that surrounding crop or product. Accordingly, a harvested product (i.e. aharvested crop or other agricultural food product) can similarly be indirectly protected from a fungus or fungal infection by applying a compound or composition of the invention, e.g. by spraying or fumigation, to a container or facility in which the harvested product may be sorted, cleaned, stored, packed, transported, processed or otherwise handled, or by applying a compound or composition of the invention to surrounding crop or product to inhibit or prevent transmission of a fungus or fungal infection from that surrounding crop or product.

[0102] In the context of the present specification, the terms “inhibit”, “inhibiting”, and the like when used in relation to any parameter of fungal growth, development, function or behaviour following the application of a compound in accordance with embodiments of the present disclosure, will be understood to refer to any inhibition of the selected parameter as a result of the application when compared to the absence of the application. In embodiments of the present disclosure, application of the tropone or derivative or salt thereof may inhibit or reduce fungus or fungal pathogen growth by, for example, about 20%, about 25%, about 30%, about 35%, about 40%, about 45%, about 50%, about 55%, about 60%, about 65%, about 70%, about 75%, about 80%, about 85%, about 90%, about 95% or about 100%, relative to the growth of the fungus or fungal pathogen in the absence of the tropone or derivative or salt thereof.

[0103] In the context of a fungal infection, as used herein the terms "treat", “treatment”, "preventing" and "prevention" should be understood to refer to the process of suppressing, inhibiting, or reducing the growth of a fungus, in particular a fungal pathogen of a plant, and pathogen. In the context of fungal plant diseases, as used herein the terms "treating", “treatment”, "preventing" and "prevention" refer to any and all uses which remedy a disease condition or symptoms caused by or associated with a fungal pathogen infection, prevent the establishment of a disease caused by or associated with a fungal pathogen infection, or otherwise prevent, hinder, retard, or reverse the progression of a disease or other undesirable symptoms caused by or associated with a fungal pathogen infection in any way whatsoever. Thus the terms "treating" and "preventing" and the like are to be considered in their broadest context. For example, treatment does not necessarily imply that the plant is treated until total recovery from the disease. In conditions which display or are characterized by multiple symptoms, the treatment or prevention need not necessarily remedy, prevent, hinder, retard, or reverse all of said symptoms, but may prevent, hinder, retard, or reverse one or more of said symptoms. In the context of some plant diseases caused by or associated with a fungal pathogen infection, methods of the present 1disclosure involve “treating” the disease in terms of reducing or ameliorating the occurrence of a highly undesirable event associated with the disease or an irreversible outcome of the progression of the disease but may not of itself prevent the initial occurrence of the event or outcome. Accordingly, treatment includes amelioration of the symptoms of a particular disease or preventing or otherwise reducing the risk of developing a particular disease.

[0104] As used herein reference to "reducing the susceptibility" of a plant to a fungal pathogenic infection should be understood to refer to the process of protecting the plant from infection by a fungal pathogen, including protecting a healthy plant free from disease. It should be understood that a reduction in susceptibility does not necessarily imply that a plant will no longer develop a pathogenic infection. Rather a reduction in susceptibility means that the likelihood that a plant will develop a disease caused by or associated with a fungal pathogen infection is less than the likelihood that a plant which has not undergone treatment will develop a disease caused by or associated with a fungal pathogen infection. For example reduction in susceptibility could include slowing the growth of the fungus on the plant product or seed.

[0105] The fungus against which the methods and compositions of the present disclosure may be employed may be a filamentous or non-filamentous fungus. The pathogen may infect the roots and seeds of important crops and natural landscapes. Some fungal species infect seed, transmit to the plant and spread throughout the crop and field. Illustrative examples of fungi, and in particular fungal pathogens, against which the methods and compositions of the present disclosure may be employed include fungi belonging to a genus selected from Alternaria, Ascochyta, Aspergillus, Botrytis, Colletotrichum, Fusarium, Gaeumannomyces, Gibberella, Leptosphaeria, Magnaporthe, Mycosphaerella, Penicillium, Pythium, Phytophthora, Rhizoctonia, Sclerotinia, Ustilago, Verticillium, and Zymoseptoria.

[0106] For example, the pathogen may be an Alternaria sp. (e.g. a causative agent of blight), such as A. brassicicola. For example, the pathogen may be an Aspergillus sp. (e.g. a causative agent of black mold in legumes, fruits, and vegetables), such as A. niger. For example, the pathogen may be a Botrytis sp. (e.g. a causative agent of botrytis bunch rot and grey mould / gray mold in grapes), such as B. cinerea. For example, the pathogen may be a Colletotrichum sp. (e.g. a causative agent of anthracnose). For example, the pathogen may be a Fusarium sp. (e.g. a causative agent of Fusarium wilt disease, Fusarium crown rot disease and Fusarium head blight) such as F. oxysporum, F. graminearum and F. pseduograminearum). For example, the pathogen may be a Gaeumannomyces sp. (e.g. acausative agent of take-all root rot), such as G. graminis. For example, the pathogen may be a Leptosphaeria sp. (e.g. a causative agent of blackleg), such as L. maculans. For example, the pathogen may be a Magnaporthe sp. (e.g. a causative agent of rice blast), such as M. grisea. For example, the pathogen may be Penicillium sp. (e.g. commonly associated with food spoilage). For example, the pathogen may be a Rhizoctonia sp. (e.g. a causative agent of root and hypocotyl rot in sugar beet, and of bare patch in cereals, and brown patch on turfgrass, black scurf in potatoes, and sheath blight in rice), such as R. solani. For example, the pathogen may be a Ustilago sp. (e.g. a causative agent of smut). For example, the pathogen may be a Verticillium sp. (e.g. a causative agent Verticillium wilt), such as V. dahliae. For example, the pathogen may be a Zymoseptoria sp. (e.g. a causative agent of septoria leaf blotch in wheat), such as Z. tritici, which are difficult to control due to resistance to synthetic fungicides.

[0107] In exemplary embodiments, the fungal pathogen is selected from: a Verticillium, including V. dahliae, a Fusarium, including F. oxysporum (such as F. oxysporum medicaginis) a Sclerotinia, including S. sclerotiorunr, a Rhizoctonia, including R. solani (such as R solani AG-2); a Penici Ilium, xncXudm^ l’.cilrinum; and a Zymoseptoria, including Z. tritici.

[0108] The fungal pathogens against which the methods and compositions of the present disclosure may be employed include pathogens that damage harvested crops and agricultural food products after harvest and during storage causing spoilage and food loss. For example, the pathogen may be an Aspergillus sp. (e.g. a causative agent of black mold in legumes, fruits, and vegetables), pathogen may be A.niger. For example, the pathogen may be a Penicillium sp. (e.g. commonly associated with food spoilage especially citrus, as well as spices and cereals), the pathogen may be a P.citrinum. For example, the pathogen may be a Colletotrichum sp. (e.g. a causative agent of anthracnose) which requires postharvest treatment. For example, the pathogen may be a Sclerotinia sp. (e.g. a causative agent of Sclerotinia stem rot, also known as white mould / mold, cottony rot, watery soft rot, and blossom blight on a range of crops such as brassicas, curcurbits, leafy greens and root / bulb crops), such as S. sclerotiorum. For example, the pathogen may be a Botrytis sp. (e.g. a causative agent of botrytis bunch rot and grey mould / gray mold in grapes, strawberries and other fruit), such as B. cinerea.

[0109] The potential to inhibit or prevent the growth of a fungal plant pathogen, reduce susceptibility of a plant to a fungal infection, treat or prevent a fungal pathogeninfection of a plant, or treat or prevent a fungal plant disease, has significant potential commercial benefit in agriculture and horticulture generally, for example in crop growth and production, horticulture for food or fibre, ornamentals, native ecosystem establishment and rehabilitation, plantation forestry, mine site restoration, landscaping, agriculture, plant propagation in nurseries, and other related industries. These benefits may manifest in plants grown under a variety of conditions (including, for example, field, glasshouse, container or vat grown).

[0110] Accordingly, the present disclosure may be applied to any plant species affected by a fungal pathogen as described herein. The plant may be a monocotyledon or dicotyledon, may be an annual or perennial, and may be evergreen or deciduous. The plant may be: a grass or cereal, e.g. wheat, barley, corn, oats, rice, rye, sorghum, maize, or millet; a herb; a pulse crop such as chickpea, faba / broad bean, field pea, lentil, lupin, mungbean, azuki bean, navy bean, cowpea, vetch or pigeon pea; a horticultural crop for example a Vaccinium such as blueberry, cranberry, gooseberry, Ribes such as red currant and black currant, Fragaria such as a garden strawberry, a Vitis vinifera (grapevine) for example table grape, raisin or wine grape; a fruit tree such as, for example citrus, apple, avocado, olive, avocado, stone fruit, coconut, pear, or date palm; an oilseed plant including soybean, sunflower, rapeseed (canola), cotton, peanut, flax (linseed) or castor bean; Solanaceae (nightshade family) e.g. tomatoes, eggplants, bell peppers, potatoes; Brassicaceae (mustard family) e.g. cauliflower, cabbage, brussels sprouts, broccoli; Allium family e.g. onions, garlic, leek, shallot, chives; Carrots (Apiaceae),' Lettuce (Asleraceae), Cucurbitaceae family of plants including melon, cantaloupe, cucumber, calabash, squash, and pumpkin; a herbaceous flowering plant from the genus Musa e.g. banana, a horticultural flowering plant; or other crop species such as, coffee and tea. The listed plant species are provided by way of illustration only, and the scope of the present disclosure will be understood to not be limited to the illustrations provided.

[0111] In exemplary embodiments, the plant is selected from a crop plant, such as a cereal crop, oilseed crop, grain crop, horticultural crop, or a crop for fibre production or ornamentals.

[0112] Compounds and compositions employed in accordance with the present disclosure may be applied to any surface on which the fungus grows or is capable of growing, or to any environs in which the fungus grows or is capable of growing. For aspects and embodiments of the disclosure relating to inhibiting or preventing the growth of a fungalplant pathogen, reducing susceptibility of a plant to a fungal infection, for treating or preventing a fungal pathogen infection of a plant, or for treating or preventing a fungal plant disease, the tropone or derivative or salt thereof may be applied to the plant, a plant part or the soil (or other plant germination, propagation or growth media) or surrounds in which the plant is grown or is to be grown.

[0113] In accordance with the present disclosure, the term “plant” includes within its meaning a whole plant, any reproductive or developmental form or stage thereof, or to a part or fragment of a plant. The term "plant" may therefore be used to encompass plant propagules, seedlings, germinants, tube stock and mature plants or any parts or fragments thereof, including but not limited to hypocotyls, leaves, branches, stems, roots, heads / kernels, crown, tissue samples, seeds, fruits, nuts, flowers or cones.

[0114] The terms "seed" and "seeds" are used interchangeably herein and mean seeds, typically viable seeds, to which compounds and compositions in accordance with the present disclosure may be applied. It should also be understood that reference to a "seed" as provided herein means seeds that are capable of germinating to at least conventional levels of germination typical of the relevant plant species under consideration.

[0115] For the purposes of the present disclosure, the term “plant part” includes any component of a plant, including seed, roots, leaves, stems or a reproductive structure including flowers, fruits and nuts. The term “plant part” also includes any harvested component of a plant, such as harvested grain, leaves, fruits or vegetables, and thus the term will be understood to encompass harvested crops.

[0116] The term “plant surrounds” refers to the soil or other plant germination, propagation or growth media in which the plant is growing or maintained, and which is in the immediate vicinity of the plant, such that upon application, the compound applied in accordance with the present disclosure is capable of reaching and contacting the roots of the plant.

[0117] To protect against effects of post-harvest pathogens such as, for example, Aspergillus, Colletotrichum, Penicillium, Botrytis and Sclerotinia, compounds and compositions as described herein may be applied directly or indirectly to product harvested from a plant, for example, fruits, vegetables, grain, cereals, nuts, oilseeds, or flowers. For example, application of the compound or composition may be by fumigation, such as inpost-harvest facilities in which harvested product is sorted, cleaned, stored, packed, transported, processed or otherwise handled. As such, application of the compound or composition, e.g. by fumigation, may treat or prevent fungal infection of a harvested crop or agricultural food product, inhibit or prevent the growth of a fungus on a harvested crop or agricultural food product, reduce susceptibility of a harvested crop or agricultural food product to a fungal infection, typically thereby protecting the harvested crop or agricultural food product from spoilage. Such protection may be direct where the compound or composition is directly applied to the harvested crop or agricultural food product. Alternatively, or in addition, protection may be indirect where a harvested crop or agricultural food product is protected from infection by either application of the compound or composition to a post-harvest facility, or to surrounding crop or product to inhibit or prevent transmission of a fungus or fungal infection from that surrounding crop or product.

[0118] Optionally, methods of the present disclosure are employed by means of fumigation. Fumigation can be carried out by a number of means well known to those skilled in the art. A fumigant composition as described herein may be introduced into a container or facility, typically an airtight container or facility, as a gas, vapour or volatilized liquid, with the fumigant diffusing through the container or facility disrupting or destroying fungal spores or hyphae, for example. The composition may be heated before or during introduction into the container or facility sufficiently to ensure that the fumigant chemical, typically tropone, in the composition is vapourised. In the case of fumigation of plants, plant parts, crops and agricultural products as described herein, fumigation may, for example be carried out in a silo, warehouse or other chamber. For fumigation of plants in situ, soil or other propagation or growth media, fumigation may be achieved, for example, by drip fumigation, introducing and dispersing a fumigant composition through an irrigation system.

[0119] In some cases, fumigants may be applied through slow-release formulations or impregnated packaging materials, allowing for sustained protection during storage and transport. Microencapsulation and vapor-phase dispensers may be used to regulate the release rate and maintain a consistent antifungal atmosphere. After fumigation, the product may be aerated to remove residual gases or vapours, for example ensuring that residue levels comply with food safety regulations.

[0120] Accordingly, methods and compositions described herein may be used to protect harvested crops and agricultural food products from spoilage caused by fungal pathogens and to prolong the shelflife of harvested crops and agricultural food products.Accordingly, another aspect of the present disclosure provides a method for protecting a harvested crop or agricultural food product from spoilage caused by a fungal pathogen, comprising applying to the harvested crop or agricultural food product, or to a post-harvest facility, e.g. in which the harvested crop or agricultural food product is sorted, cleaned, stored, packed, transported, processed or otherwise handled, a compound selected from tropone and a derivative or salt thereof, wherein where the compound is a derivative of tropone the derivative is a compound of Formula (I) or a salt thereofO& = / (R2)n (I) wherein:R1and R2are independently selected from the group consisting of alkyl, alkenyl, alkynyl, alkoxy, carboxyl, carbamoyl, acyl, aryl, heteroaryl, amino, alkylamino, cycloalkyl, cycloalkenyl, cycloalkynyl, heterocyclyl, halogen, cyano, nitro, NCS, SCN, alkylcarbonyl, alkylthiocarbonyl, alkoxycarbonyl and aminocarbonyl; and n is 0, 1, 2, 3 or 4.The harvested crop or agricultural food product may comprise one or more of fruits, vegetables, grain, cereals, nuts, oilseeds, or flowers. The post-harvest facility may include, for example, a shed, warehouse, silo, cool room, storeroom, container or the like. A postharvest facility as defined herein also includes a point-of-sale facility.Compounds and compositions to be employed in accordance with the present disclosure are typically applied to the surface, environs, plant, plant part or plant surrounds in the form of a composition comprising one or more suitable carriers, adjuvants and / or diluents. Accordingly, provided herein are antifungal compositions comprising tropone or a derivative, in combination with one or more one or more suitable carriers, diluents or adjuvants, optionally one or more one or more agriculturally acceptable carriers, diluents or adjuvants, wherein where the compound is a derivative of tropone the derivative is a compound of Formula (I) or a salt thereofO&(R2)n (I)wherein:R1and R2are independently selected from the group consisting of alkyl, alkenyl, alkynyl, alkoxy, carboxyl, carbamoyl, acyl, aryl, heteroaryl, amino, alkylamino, cycloalkyl, cycloalkenyl, cycloalkynyl, heterocyclyl, halogen, cyano, nitro, NCS, SCN, alkylcarbonyl, alkylthiocarbonyl, alkoxycarbonyl and aminocarbonyl; and n is 0, 1, 2, 3 or 4.

[0121] Compositions suitable for use in accordance with the present disclosure may be in liquid, gaseous, vapourised or solid form. A liquid composition can be used per se, for example, as a dip or spray to inoculate seeds, plants, soils or other plant germination, propagation or growth media, or as a fumigant composition. Seeds coated with the liquid composition may be subsequently dried and stored for future use. The liquid composition may be further formulated with an agriculturally acceptable diluent or carrier to form a spray, foam, fogging, mist, drench, slurry, gel, dip, emulsion or paste and optionally combined with one or more co-formulants. Suitable carriers include polymers, water, aqueous solution, slurries, granules, or powders.Provided herein are fumigant compositions comprising tropone or a derivative or salt thereof, wherein the derivative is a compound of Formula (I) or a salt thereof, wherein where the compound is a derivative of tropone the derivative is a compound of Formula (I) or a salt thereofO 6 " = (R2)n (I) wherein:R1and R2are independently selected from the group consisting of alkyl, alkenyl, alkynyl, alkoxy, carboxyl, carbamoyl, acyl, aryl, heteroaryl, amino, alkylamino, cycloalkyl, cycloalkenyl, cycloalkynyl, heterocyclyl, halogen, cyano, nitro, NCS, SCN, alkylcarbonyl, alkylthiocarbonyl, alkoxycarbonyl and aminocarbonyl; and n is 0, 1, 2, 3 or 4.

[0122] The fumigant composition may be in the form of a gaseous, vapourised or liquid composition, e.g. an aqueous composition. The fumigant composition may be employed to inhibit or prevent growth of a fungus, treat or prevent fungal pathogen infectionor fungal plant disease, protect a crop or product harvested from a plant from a fungal pathogen, or protect a harvested crop or agricultural food product from spoilage caused by a fungal pathogen. The fumigant composition may be applied directly to a plant, lant part, or plant surrounds. The fumigant composition may be applied to a crop or product harvested from a plant including an agricultural food product. The product may be a stored product contained within a storage container or facility and / or contained within packaging material, with the fumigant composition designed to penetrate the storage container or facility or the packaging material.

[0123] A composition in solid form may be produced by drying of a liquid composition of the present disclosure. Solid compositions may comprise one or more agriculturally acceptable carriers such as seed, lime, kaolin, maize chip, humate and diatomite, polymers or mixtures thereof. For example, a solid composition may be provided in the form of a powder which may be dusted onto plants or plant parts. Alternatively, a solid composition may be prepared in the form of pellets, granules or prills using known techniques in the art. Pellets, granules or prills may be particularly useful for sowing into new pastures or over-sowing of older established pastures.

[0124] A composition may include one suitable for coating a film, plastic, cardboard or other packaging material. The composition may, for example, be provided in the form of a slow-release sachet by absorption into or onto charcoal or other suitable carrier material to provide for slow release or controlled release over time.

[0125] In accordance with the present disclosure a compound or composition as described herein may be applied alone, or in combination with one or more other agents or additives, such as, but not limited to, surfactants, adjuvants, wetting agents, humectants, stickers, spreaders, stabilisers, emulsifiers, penetrants to enhance activity, stressing agents to improve spore vigour, UV protectants and plant-protecting substances, or mixtures thereof. Such additives may be applied separately to the same or different part of the surface, environs, plant, plant part or plant surrounds being treated with the compound or composition and may be applied at the same time, before or after treatment with the compound or composition. In another embodiment, such agents or additives may be included in a composition comprising the tropone or derivative thereof as described herein. Such agents or additives may be used to bundle materials onto the seed in a pre-sowing treatment or to form a seed coat to improve seed quality and reduce susceptibility to fungal pathogens.

[0126] Examples of plant-protecting substances, include, for example, chemical fertilizers, insecticides, fungicides, nematicides, antibiotics, organic fertilizers, herbicides, nutrients, or micronutrients. Examples of stressing agents include potassium chloride, sodium chloride, glycerol and glucose.

[0127] Reference to an "adjuvant" as used herein includes any additive that has the function of improving, modifying, or aiding the activity or application characteristics of the composition. For example, in relation to an aqueous solution, an adjuvant may function to improve the spreadability and / or wettability of the composition, or to modify droplet formation and / or behavior.

[0128] Examples of adjuvants that may be included in an aqueous solution to be applied to a plant or plant part, include, for example, esterified oil (e.g. esterified vegetable oil), vegetable oil, anionic, cationic, non-ionic or amphiphilic surfactants, which may be used to improve dispersibility, wettability, penetration and / or translocation, and for effecting miscibility and stability of the preparation in a ready-to-use dilution. The adjuvant may be a mixture of the above, for example, an esterified oil based product with non-ionic surfactants.

[0129] The composition may also comprise other adjuvants, such as pH modifiers, carriers, anti-foaming agents, thickening agents, anti-freezing agents, organic solvents (preferably water-miscible solvents), preservatives, and colouring agents. In solid forms, such as granules, powders and tablets inert inorganic (e.g., silica, salts) or organic (e.g., cellulose, polyacrylates, urea) compounds may be employed as carriers for diluting the organic acid or adsorbing moisture. Such solid forms may be prepared by a variety of standard methods known to those skilled in the art, for example, by disc granulation, spray drying, fluidized bed granulation, mixing granulation by a vertical mixer or paddle mixer, or by extrusion, compacting, centrifugal jet layer, or spraying / cooling granulation.

[0130] Additives may also include compositions which assist in storage, for example unrefined corn oil and so called invert emulsions containing a mixture of oils and waxes on the outside and water, sodium alginate and conidia on the inside. Examples of surfactants, spreaders, penetrants, and stickers include Fortune®, Pulse®, C-Daxoil®, Codacide Oil®, D-C. Tate®, Supamet Oil, Bond®, Citowett® and Freeway®. This list of additives is for illustrative purposes only.

[0131] Compositions in accordance with the present disclosure may also include acidulants, alginates, mannans, glycerol, polysaccharides, cellulose, xylans, carageenans, nutrients, trace elements, minerals, proteins, fats, soluble carbohydrates, insoluble carbohydrates and vitamins, and additives to extend shelf life.

[0132] Compounds as described herein and compositions comprising same are typically applied in accordance with the present disclosure in an effective concentration or amount. The exact amount or concentration required will vary from application to application depending on factors such as the identity of the compound to be applied, the species of plant being treated, the age and general condition of the plant, whether the plant is treated prior to planting or in situ, soil conditions such as soil type, salinity, water content, acidity, nutrient levels and organic matter composition, climactic factors such as temperature and rainfall, the mode of application, the form in which the composition is applied, the identity and number of pathogens infecting the plant, the severity of infection or disease at the time of administration and so forth. Thus, it is not possible to specify an exact “effective concentration” or "effective amount".

[0133] To apply a composition to a plant or plant part in accordance with the present disclosure, any method suitable for the purpose may be used. The composition can be applied to the plant by dry or wet formulation for example, as a liquid, powder, emulsion or paste. The application method will typically depend on the plant part which is to be treated for or which is susceptible to, pathogen infection. For example, a xanthan gum or polymer based seed coat may be used for treating or preventing root diseases and an aqueous spray, including an adjuvant or surfactant to help improve leaf wetting, may be used for foliar diseases.

[0134] In accordance with the present disclosure, an aqueous solution comprising the compound described herein or a composition thereof may be applied directly to the plant, plant part or plant surrounds. The plant may be treated, for example, by fumigation, and / or by application of an aqueous solution to the foliage, flowers, stem or base of the plant, to a plant propagule or to the plant roots. The compositions disclosed herein may be applied to the foliage by, for example, high or low pressure spray application. Foliar application can also be carried out by coating, immersion, or dusting. The compositions can also be used in hydroponic systems including soilless bags, and rockwool. In an embodiment, the roots of a plant may be soaked in a liquid solution comprising a composition as described herein. A composition may be applied to a plant propagule such as a seed. In a particular embodiment,plants or plant propagules may be treated prior to planting in the plant growth medium (e.g., soil) in the location where they are to be grown, for example, as seeds, seedlings, young germinants, tube stock, or other form of potted plant. In a particular embodiment of the disclosure, treating a plant takes place prior to planting by soaking or contacting the seed with a solution (typically an aqueous solution) comprising the composition. In a particular embodiment, the seed may coated with the composition. In an alternative embodiment, plants or plant propagules may be treated when planted in the location in which they are to be grown (i.e. in situ).

[0135] In another embodiment, a composition as described herein may be applied to the soil, e.g. as a powder or granules, then watered into the soil. In one embodiment, for application to soil, pastures, or turf, pellets or prills are sown into soil with seed, or over sown into pastures or turf with or without seed. In an alternate embodiment the composition is applied to existing pastures or turf in the form of a wettable powder as a root drench.

[0136] In alternative embodiments, compounds and compositions as described herein may be applied directly to product harvested from a plant, for example, fruits, vegetables, grain, cereals, nuts, oilseeds, flowers etc., in particular in order to protect the product from the effects of past-harvest pathogens such as, for example, Aspergillus, Colletotrichum, Penicillium, Botrytis and Sclerotinia.

[0137] It will be appreciated that the above described terms and associated definitions are used for the purpose of explanation only and are not intended to be limiting.

[0138] The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that the prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates.

[0139] Those skilled in the art will appreciate that the invention described herein is susceptible to variations and modifications other than those specifically described. It is to be understood that the invention includes all such variations and modifications. The invention also includes all of the steps, features, compositions and compounds referred to or indicated in this specification, individually or collectively, and any and all combinations of any two or more of said steps or features.

[0140] The present disclosure will now be described with reference to the following specific examples, which should not be construed as in any way limiting the scope of the invention.EXAMPLES

[0141] The following examples are illustrative of the methods disclosed herein and should not be construed as limiting in any way the general nature of the disclosure of the description throughout this specification.EXAMPLE 1Experimental proceduresStreptomyces MH71

[0142] Streptomyces sp. MH71 is a strain with strong in vitro and in planta antifungal activity against phytopathogen Fusarium pseudograminearum, as previously described by O’Sullivan et al. (2021). The strain was isolated in August 2000 from the root endosphere of field grown wheat plants in Western Australia (O’ Sullivan et al. 2021). MH71 was deposited under Accession Number VI 7 / 004100 with the National Measurement Institute (NMI), Australia on 21 February 2017 and is disclosed in WO 2019 / 046909, the disclosure of which is incorporated herein by reference.

[0143] MH7 1 was routinely cultured and maintained in half-strength potato dextrose agar (’APDA, 19.5 g L'1potato dextrose broth and 7.5 g L'1of bacteriological agar) and incubated at 28 °C. Glycerol spore stocks were generated from mature MH71 colonies cultured in ' / / PDA at 28 °C, by gently scraping off spores in sterile water, filtering through cotton wool to remove mycelial fragments, before storing in 20 % sterile glycerol at -80 °C. A working spore solution of 1 x 106cfu mL'1(colony forming units, cfu) in sterile water was calculated from a decimal dilution series on 'APDA plates. Spores were first heat shocked for 5 min at 55 °C before adding to liquid cultures.Time-course fermentation ofMH71 and isolation of crude extracts

[0144] Triplicate liquid cultures of MH71 were prepared by inoculating 100 pL of activated spores to 200 mL of YME liquid culture medium in 250 mL baffled flasks and grown at 28 °C in a 200 rpm orbital shaker. Samples of 20 mL were harvested from each replicate culture at 24, 48, 72, 96, 120, 144 and 168 hours of fermentation, totalling 21samples. After collection, samples were immediately filtered under vacuum through a 0.2 pm PES bottle top filter (Nalgene Rapid-Flow) to separate the cell-free spent media from Streptomyces cells. Samples of cell-free spent media were stored at -80 °C for antifungal bioassays and metabolomics. Cells were scraped off with a sterile utensil, transferred to sterile tube, flash frozen in liquid nitrogen, then stored at -80 °C for transcriptomics. Glucose consumption was measured daily using a glucose colorimetric detection kit (Invitrogen) according to the manufacturer instructions, with a detection range between 0.27 and 1.7 mM.Antifungal activity ofMH71 ferment against phytopathogen Verticillium

[0145] Verticillium dahliae strain Vd71171 (BRIP71171, Queensland Department of Agriculture and Fisheries culture collection) was selected as a representative fungal phytopathogen to evaluate the antifungal activity of each time point during Streptomyces sp. MH71 fermentation. Growth inhibition of Verticillium dahliae was determined using an enhanced green fluorescent protein (eGFP)-labeled transformant (Vd71171-eGFP) previously reported by Sabburg et al. (2021). Fresh cultures of Vd71171-eGFP were set up by inoculating 10 pL of a spore cryostock in the centre of a ' / / PDA plate for 7 days at room temperature in the dark to allow sporulation. Approximately 3 cm2of colonised agar was excised from the plate and transferred to 15 mL of half-strength potato dextrose broth (APDB), vortexed to dislodge spores and filtered through a nylon 40 pm cell strainer. Working spore concentration was quantified using a haemocytometer (C-CHIP DHC-N01- S, iNCYTO), and 'APDB was added to adjust spore stock to 5 * 105spores mL'1.

[0146] The antifungal activity cell-free spent media from the triplicate liquid cultures of MH71 was evaluated over seven days of culturing. Samples of spent media from each day were diluted in water in equal parts, and two-fold serial dilutions of each extract were prepared to obtain a dilution range from 50 to 0.024 % (v / v) in a 96-well plate. The dilutions were mixed with an equal volume of Vd71171-eGFP in a 384-well plate, resulting in a final volume of 60 pL and a concentration range of 25 to 0.012 % (v / v). Also tested in the assay were negative (no pathogen spores) and positive controls (no spent media). The growth response of Vd71171-eGFP to MH71 spent media was monitored hourly for 20h at room temperature. Automated GFP-fluorescent imaging was conducted using a Cytation 1 reader (Biotek) fitted with a GFP fluorescence filter cube (excitation 469 nm and emission 525 nm) and controlled by Gen5 software (v3.08 Biotek). Image settings were adjusted following Sabburg et al., (2021), with a few modifications. Briefly, images were captured using a 10x objective, with LED intensity 10, 100 ms exposure and detector gain of 4 to obtain in focusimages. The object size was set to be between 5 and 100 gm including edge objects with the splitting of touching objects. Background flattening during object detection was performed automatically. Fungal growth was quantified using the Cellular Analysis feature in Gen5 with object sum area used as a measure of fungal growth (spore germination and mycelia extension) through the sum of GFP intensity on each well. Object sum area was calculated with background-corrected images, detecting object sizes between 1 and 10000 pm, and including edge objects. Fitted response curves of Verticillium inhibition and half maximal inhibitory concentration (IC59, v / v) for the spent media samples harvested at 24, 48, 72, 96, 120, 144 and 168 hours of fermentation were determined using the drc R package (v3.0-l). The time-course experiment and the bioassay to evaluate antifungal activity were repeated three times to confirm the results.Metabolomic analysis and identification of antifungal compounds

[0147] The inventors aimed to understand the metabolome of MH71, including both soluble and volatile compounds. 5 mL of cell-free spent media collected at 72 and 96 hours of fermentation, as well as control samples of uninoculated YME medium were loaded on a Phenomenex solid phase cartridge (C18E, 500 mg) and extracted with three elutions of 500 pL methanol (MeOH). The elute was dried under nitrogen gas and redissolved in 200 pL chromatography -grade MeOH. A quality-control ‘mixed’ sample was prepared containing 5 pL of each extract.Liquid chromatography mass spectrometry (LCMS) methodology

[0148] 2 pL of each sample were injected onto ultra-high-performance liquid chromatography-high resolution mass spectrometry (UHPLC-HRMS) system (Thermo Scientific). Chromatographic separations were performed on a Waters acquity Premier BEH C18 UHPLC column (1.7pm, 2.1 x 50mm), at a flow rate 0.3 mL min'1. The mobile phase was water and acetonitrile (MeCN), both containing 0.1 % formic acid. The elution profile was the following: 0-2 min 5% MeCN, 2-10 min increasing to 95 % MeCN, 10-12 min hold at 95 % MeCN, 12-15 min 5 % MeCN. Mass spectrometry (MS) data were acquired using an Orbitrap Fusion performing electrospray ionisation, running in data dependent acquisition mode. Initial master scans were run at a resolution of 60K, with five dependent scans selected for secondary MS. Fragmentation was performed with a stepwise High-energy collisional dissociation (HCD) mode, with normalised collision energies of 15, 30 and 60 %. Apex detection was set to full width half maxima of 8 seconds, and a 15 second dynamic exclusion. Secondary MS was run at a resolution of 15 K. Data were acquired in both positive andnegative ionisation mode, given that some predicted secondary metabolites are not easily ionised in positive mode. LCMS raw data were analysed in MSDial (v4.90). Aligned spectra were exported as peak lists and used for statistical analyses with Metaboanalyst (version 6.0). Aligned MS2spectra were screened against the VS17 authentic standards spectral library (https: / / systemsomicslab.github.io / compms / index.html). Data of particular interest, which did not match standards in the spectral library were analysed using MSFinder (v3.60). Standards of nigericin and elaiophylin (Bioaustralis) were prepared in MeOH at a concentration of 1 ppm and analysed using the same methodology.Headspace GCMS

[0149] A headspace GCMS analysis was carried out to identify volatile compounds at 72 and 96 hours of fermentation, as these can be challenging to detect through conventional LC-MS methods. A 1 mL sample of MH71 culture was drawn from each flask and added into 10 mL GCMS vials. The vials were sealed with septa and incubated for Ih at 28 °C, along with 3 samples of uninoculated media. Samples were analysed on a Shimadzu GC2010 gas chromatograph coupled to a GCMS-QP2010 electron impact mass spectrometer, with a PAT HTX headspace autosampler. Vials were held at 8 °C before solid phase microextraction (SPME) using a Stableflex DVB / CAR / PDMS SPME fibre (Supelco). First, samples were incubated for 5min at 30 °C with shaking, before SPME needle insertion and equilibration (30 min at 30 °C, 5 min desorption time). The SPME fibre was injected using splitless injection onto an SH-Stabilwax column (0.25 pm thickness, 0.25 mm diameter, 250 °C injection temperature) with helium carrier gas and a linear velocity of 30 cm s'1. The oven temperature program was as follows: 5.5 min at 55 °C; 8 min ramp to 170 °C; 12 min ramp to 250 °C; 5.5 min hold at 250 °C. Electron impact ionisation was performed at 200 °C (interface temperature of 250 °C). Features were compared to the NIST database for identification. A neat commercial standard of tropone (2,4,6-Cycloheptatrien- 1-one, Bioaustralis) was analysed using the same methodology to confirm identification. Peak tables were exported and analysed using Metaboanalyst. All features detected in uninoculated media controls were excluded from analysis.EXAMPLE 2Anti-Verticillium activity of MH 71 -excreted metabolites

[0150] The inventors measured glucose levels in cell-free spent media samples collected over seven days of fermentation of MH71, to determine the phases of the bacterial growth cycle. Glucose levels dropped rapidly after 48 h and were close to none after 96 h offermentation, suggesting the exponential growth phase extended until 72 h and after 96 h, growth reached the stationary phase in MH71 (Fig. 1A). The antifungal activity of the spent media collected over time was evaluated after 15 h incubation with the eGFP-labelled fungal phytopathogen Verticillium dahliae (Vd71171-eGFP). V. dahliae is a widely distributed phytophathogen causing verticillium wilt (characterised by leaf curl and discolouration) in a large number of crop species.

[0151] Fungal growth was significantly inhibited when incubated with spent media collected at 96 h fermentation, steadily increasing antifungal activity until 144 h, followed by a small reduction in activity at 168 h (Fig. IB and Fig. 1C). Compared to the positive (untreated) control, incubation of V. dahliae with 96 h spent media at a concentration over 0.781 % (v / v) strongly inhibited spore germination, and mycelial growth and branching. The IC50 values for each time point were determined, showing a 29-fold decrease in IC50 from 96 to 144 hours, indicating an increase in antifungal potency, followed by a slight increase in IC50 from 144 to 168 hours, suggesting a minor reduction in metabolite secretion or availability.

[0152] The secondary metabolism of MH71 was significantly activated at transcript and metabolite levels, coinciding with the inhibition of V. dahliae and the onset of the stationary growth phase (96 h). Antifungal bioactivity increased over time in batch culture but was not detectable before 96 h. Studies evaluating the antifungal activity of other Streptomyces antimycoticus strains support the exhibited antifungal activity against necrotrophic fungal phytopathogens, such as Fusarium, Rhizoctonia and Botrytis species (Koch & Loftier, 2009). Without wishing to be bound by theory, the inventors suggest that the reduction of bioactivity at later time points (168 h) is likely due to the breakdown of antifungal metabolites.EXAMPLE 3Differential gene expression between 72 and 96 hours of fermentation

[0153] The genome of the root endophyte Streptomyces sp. MH71 was sequenced using the PacBio Sequel II sequencing platform. A total of 9,521 genes were identified in MH71 genome assembly using the annotator PGAP. This included 9,069 annotated proteincoding genes, 65 tRNA, and 18 rRNA genes. Taxonomic analysis using GTDB-tk indicated that strain MH71 belongs to the genus Streptomyces and provisional species-level with 96.74 % identity was assigned to the species Streptomyces antimycoticus. The genome of MH71was surveyed for biosynthetic gene clusters (BGCs).

[0154] Whole-transcriptome analyses were performed at both exponential (72 h) and stationary (96 h) growth phases of MH71 to explore the relationships between antifungal activity and transcription of MH71 biosynthetic gene clusters (BGCs). The transcription data revealed that 9,056 out of the 9,521 predicted genes had read coverage (95.1 %), and from those 2,774 genes had significantly different expression between 96 and 72 h, with 1,423 (14.9 %) genes being upregulated, 1,351 (14.2 %) genes being downregulated, and 17 outliers (not part of the analysis).EXAMPLE 4Differential metabolite production in MH71

[0155] Using an untargeted metabolomics approach, 6 out of the 17 BGCs with a known metabolic product could be identified and detected using LC-MS with a general increase in relative abundance from 72 to 96 hours. In positive ionisation experiments, several features corresponded to the predicted masses and fragmentation pattern of the known antifungal niphimycin. The siderophores coelichelin and desferrioxamine were also detected. In negative ionisation experiments, the detection of elaiophylin was confirmed via comparison with a commercial standard. Pristinol, ectoine, echosides and nigericin were not detected in any sample despite the high similarity (100 %) of the predicted biosynthetic gene cluster to known BGCs. Niphimycin C displayed a 4.5-fold change in abundance between the two time points, while coelichelin and elaiophylin were not detected at all at 72 h, indicating a rapid differential activity of their corresponding biosynthetic pathways.

[0156] Preliminary experiments conducted with divider plates revealed that the antifungal activity of MH71 is partly attributed to volatile compounds (Fig. 2). Cultures of Streptomyces sp. MH71 were grown on one half of divided petri dishes containing YME agar, such that the opposing half of the plate was only influenced by volatile emissions. After 7 days, a disc sterile filter paper was inoculated with Verticillium dahliae 71171-eGFP and applied to the opposing side of the petri dish, and growth of the fungus was tracked and photographed over two days. In petri dishes containing MH71 growth of V. dahliae was reduced compared to petri dishes that did not contain MH71 (Fig. 2).

[0157] Given that volatile compounds are not retained in extracts for LCMS, the inventors utilised solid phase microextraction to extract the volatile emissions of MH71cultures at two different time points and GCMS data were acquired. Geosmin and three borneol congeners were detected (2-methyl-2-bornane, 2m ethyl enebornane and 2- methylisobomeol), confirming their biosynthesis, and their abundance increased at 96 h (Fig. 3A). The volatile bouquet of MH71 cultures at 72 h was predominantly esters such as methyl isovalerate, while at 96 h the bouquet was more diverse, including terpenes, as well as the seven-members aromatic compound tropone (2,4,6-cycloheptatrien-l-one) (Fig. 3B). The putative identification of tropone was confirmed using a commercial tropone standard which matched both retention time and fragmentation pattern (Fig. 4). At the transcriptional level, the genes involved in tropone production were downregulated at 96 h, while the abundance of tropone increased. Without wishing to be bound by theory, the inventors suggest that this counterintuitive regulation may be caused by Streptomyces MH71 selfregulating any potential self-toxicity.

[0158] The known BGCs annotated for Streptomyces sp. MH71, including those with previously reported antifungal activity, were integrated into a comprehensive analysis (Table 1). Most BGCs with reported antifungal activity presented a significant increase in expression at the stationary phase (96 h) compared to the exponential growth phase at 72 h fermentation. This increase was evidenced by either an elevation in transcript levels at 96 h, as in the case of amipurimycin and nigericin, or product detection using LC-MS, as in the case of niphimycin C. However, none of the antifungal metabolites were significantly overexpressed at both the transcript and metabolomics levels. BGCs with putative antifungal activity, such as mediomycin, did not show a significant increase or reduction at any of the growth phases. The only metabolites with higher expression using both transcriptomics and metabolomics were coelichelin, which showed a remarkably high fold change in metabolite relative quantities and a more moderate gene expression, and desferroxiamine, which exhibited similar fold changes across the two approaches. The only BGC with a significantly reduced expression at 96 h was the indole 5-isoprenylindole-3-carboxylate P-D-glycosyl ester, as indicated by the transcriptomics analysis. Additionally, significantly higher relative quantities of volatiles 2-Methyilsobomeol and Geosmin were detected in MH71 cultures at 96 h, but without a supporting increase in transcript level.T able 1. Shifts in BGC expression in the exponential and stationary phases in MH71 , for BGCs with high similarity (>60 %) to a known BGC cluster. BGC expression and relative quantity of detected metabolite is expressed as log2 fold change between stationary and exponential growthphases (96 h vs 72 h). Empty cells denote no metabolite detected using LC-MS or GC-MS. Asterisks denote significantly different log2 fold changes using FDR-adjusted p-values (p <0.05). When multiple metabolites could be detected for each BGC (e.g. 2-methylisobomeol and 2-methyl-bomene), that with the smallest p-value is displayed.EXAMPLE 5Antifungal activity of tropone

[0159] The inventors further investigated the antifungal activity of volatiles whose relative abundance peaked in 96-hour culture samples (see Fig. 3). In particular, the antifungal effect of tropone was evaluated against Verticillium dahliae strain Vd71171 (BRIP71171, Queensland Department of Agriculture and Fisheries culture collection, Queensland, Australia) using a disc diffusion bioassay with discs saturated with 10 pl or 20 pl of tropone standard. Sterile filter paper was inoculated with V. dahliae and applied to APDA petri dishes. Neat tropone (10 pl or 20 pl) was pipetted onto sterile filter paper (or nothing in the case of negative controls), which was stuck to the ceiling of the petri dish. Growth of the fungus was tracked and photographed over 72 h. This experiment was repeated, this time with the tropone applied to a distal edge of the agar media, with similar results (data not shown).

[0160] As shown in Fig. 5, significant inhibition zones were observed, even when the filter paper containing tropone was placed five centimetres or more apart from the fungal plug, highlighting the long-range effects of tropone. A study of genome annotation of MH71 demonstrated the existence of a phenylacetic acid degradation pathway, suggesting the capability for tropone production. However, the expression of these genes proved to be down- rather than upregulated at 96 h (data not shown).

[0161] The inventors then investigated the ability of tropone to inhibit the growth of other fungal pathogens of plants. Sterile PDA petri dishes were inoculated with filamentous fungi Fusarium oxysporum medicaginis, Rhizoctonia solani AG-2 or V. dahlias, or with the non-filamentous fungus Zymoseptoria triti d . using sterile filter paper inoculated with the fungal pathogen or an agar plug harvested from an actively growing culture. Tropone (20 pl or 40 pl in the case of F. oxysprum medicagiuis. 20 pl or 40 pl in the case of R. solani, 10 pl or 40 pl in the case of V. dahlias, and 40 pl only in the case of Z. tritici) was pipetted onto filter paper attached to the upper internal surface of each petri dish. The petri dishes were sealed and fungal growth monitored over 72 h. Note that as Z. tritica is a non-filamentous fungus, to test inhibition a single line of the fungus was struck across the plate, with the tropone source sitting directly above a point on this line, such that where growth was inhibited the line of inoculum was broken as visible in the treatment photo of Fig. 7.

[0162] Growth of each fungus in the presence of tropone was determined as a percentage relative to controls (no tropone). As shown in Fig. 6, evidence of tropone-induced growth inhibition was observed for all four fungal pathogens. Comparing growth in the presence of 40 pl tropone, V. dahliae appeared to be the most susceptible, followed by R. solani, Z. tritici and oxysporum medicaginis. In addition to fungal growth being impaired, fungal morphology was also visibly altered by tropone treatment. In two of the three filamentous fungi tested (R. solani and F. oxysporum), the colour of hyphae was altered and direction of growth was focused away from the source of tropone, producing asymmetric growth (Fig. 7).

[0163] In view of the evidence of tropone induced growth inhibition of four fungal pathogens, belonging to four different genera, the group of pathogens assayed was expanded to include Penicillium citrinum, Fusarium graminearum and Sclerotinia sclerotiorum. Petri dishes were inoculated with fungi of interest, and tropone (20 ul) pipetted onto filter paper attached to the upper internal surface of each petri dish. The petri dishes were sealed, andgrowth monitored for 72 hours. Due to the growth habit of Penicillium citrinum, the plates were observed and data recorded up to 14 days from exposure. As shown in Fig. 8, S. sclerotiorum and the citrus mold P. citrinum showed similar sensitivity to tropone as R. solani.

[0164] Not only was growth inhibited, but morphology visibly altered by tropone treatment. In R. solani, F. oxysporum and F. graminearum, the colour of hyphae was altered and direction of growth was focussed away from the source of tropone, producing asymmetric growth (Fig. 9A, B). For S. sclerotiorum, no sclerotes formed on tropone treated plates, while multiple sclerotia (dormant form or survival structure of pathogen) had formed on control plates. For P. citrinum, fungal development was also significantly impaired; tropone caused a sustained reduction of growth in P. citrinum from a single exposure so plates were incubated for an additional 7 days to observe the effect after 14 days (Fig. 9C and Fig. 10).EXAMPLE 6Inhibition of fungal growth on soft fruit using tropone

[0165] To demonstrate the ability of tropone to inhibit post-harvest fungal contamination of fruit, the inventors investigated contamination of store-bought strawberries and avocado. Strawberries and avocado with visible signs of contamination were sliced aseptically and equally distributed on to filter paper dampened with sterile water placed into petri dishes. Tropone (20 pl) was pipetted onto dry filter paper attached to the upper internal surface of the petri dish. Each petri dish was sealed, and fungal growth monitored over twelve days to view the growth habit of the contaminating fungal pathogens. Controls without tropone exposure were also included. The strawberry test samples were performed in triplicate and the avocado test samples in duplicate. At the end of the 12 days each dish was photographed. Growth of the fungus in the presence or absence of tropone was determined by tracing the total area of fungal hyphae growth relative to the total area of the fruit piece. For clarity, some of the pieces of fruit exhibited hyphae growth beyond the piece of fruit, for these samples the values assigned are greater than 100%. The results are summarised in Fig. 11. Significant reduction in growth of fungi was observed, demonstrating the ability of tropone to inhibit fungal growth on postharvest fruits.EXAMPLE 7Effect of tropone on stored grain fungal contamination

[0166] Seeds harvested from field grown wheat were dampened to induce germination of fungal spores naturally found on or within the wheat seed. Separately, the seed from the same batch of wheat seed were sterilised (autoclaved). Approximately 30 sterile wheat seeds were placed into sterile containers, wetted with 2ml of sterile water and inoculated with 3 contaminated seeds. The container was either exposed to tropone or to ambient air and sealed. The tropone treatment of 20 pl or 50 pl was pipetted onto filter paper attached to the upper internal surface of the container. The containers were sealed and fungal growth monitored over eleven days to view the growth habit of the contaminating fungi. Each test sample and control was performed in triplicate. Growth of the fungus in the presence or absence of tropone was determined by photographing individual seeds and counting those with or without visible fungal hyphal growth over the seed. The data is summarised in Fig. 12. It was observed that treatment with both 20 pl and 50 pl tropone inhibited stored grain fungal contamination of wheat seeds.EXAMPLE 8 Fungicidal effect of tropone

[0167] To assess if tropone has fungicidal activity an in vitro antifungal assay was setup to observe and record antifungal activity exhibited by tropone. In a sterile 96 well plate, 100 pl samples of tropone (neat, undiluted), tropone diluted 1 : 10 in water, a CSIRO fungicide control, and two commercial fungicide controls (analytical standards of Tebuconazole and Prothioconazole at 0.5mg / ml in water) were added to the top row (Row A) of a 96-well plate. The comparator azole fungicides are recognised as mainly fungistatic with potentially fungicidal activity at high concentrations. Two-fold dilutions of the samples were made in water down the plate (i.e. from Row A to Row B, to Row C etc). A 50 pl sample of 5xl06spores / ml (in A strength potato dextrose broth) of Verticillium dahliae fungal spores constitutively expressing a green fluorescence protein (GFP) were subsequently added to each well. The final concentration of the test antifungal agent per well is therefore half of the original amount. The plate was incubated for 1 hour to allow samples to take effect on the fungal spores. The results are shown in Fig.13 and Fig.14.

[0168] Verticillium-G¥P spores were imaged in a plate imager with both brightfield imaging (Fig. 14) and GFP imaging (Fig. 13). Where samples exhibited fungicidal effect, the Verticillium-GFP spores lose fluorescence and no GFP signal is detected. The GFP signal is white false coloured. If spores are viable, a GFP signal is detected and white within thesquare is shown. In this assay no GFP signal was detected from tropone treated Verticillium- GFP spores for dilutions down to 128-fold. Fungicide controls, and positive (untreated) controls performed as expected. Similarly, no GFP signal was detected from the negative controls which did not contain any Verticillium-G¥P spores. The assay demonstrated the fungicidal activity of tropone.REFERENCESDuan, et al. (2022). Physical separation of haplotypes in dikaryons allows benchmarking of phasing accuracy in Nanopore and HiFi assemblies with Hi-C data. Genome Biology, 23(1), 84. https: / / doi.org / 10.1186 / sl3059-022-02658-2Moffat et al. (2024) Understanding the biosynthesis, metabolic regulation, and anti- phytopathogen activity of 3,7-dihydroxytropolone in Pseudomonas spp. mBio, 15. https: / / doi.Org / 10.l 128 / mbio.01022-24O’Sullivan, et al. (2021). Developing actinobacterial endophytes as biocontrol products for Fusarium pseudograminearum in wheat. Frontiers in Bioengineering and Biotechnology, 9. https: / / doi.org / 10.3389 / fbioe.2021.691770Sabburg, R., et al. (2021). A method for high-throughput image-based antifungal screening. Journal of Microbiological Methods, 190, 106342. https: / / doi.org / 10.1016 / JMIMET.2021.106342.

Claims

CLAIMSA method for protecting a crop or product harvested from a plant from a fungal pathogen or from fungal pathogen infection, comprising directly or indirectly applying to the product or a post-harvest facility a compound selected from tropone and a derivative or salt thereof, wherein where the compound is a derivative of tropone the derivative is a compound of Formula (I) or a salt thereofwherein:R1and R2are independently selected from the group consisting of alkyl, alkenyl, alkynyl, alkoxy, carboxyl, carbamoyl, acyl, aryl, heteroaryl, amino, alkylamino, cycloalkyl, cycloalkenyl, cycloalkynyl, heterocyclyl, halogen, cyano, nitro, NCS, SCN, alkylcarbonyl, alkylthiocarbonyl, alkoxycarbonyl and aminocarbonyl; and n is 0, 1, 2, 3 or 4.

2. The method of claim 1, wherein the compound is tropone.

3. The method of claim 1 or 2, wherein the product comprises one or more of fruits, vegetables, grain, cereals, nuts, oilseeds, or flowers.

4. The method of any one of claims 1 to 3, wherein the method protects the crop or product from spoilage caused by fungal pathogens and prolongs the shelf life of harvested crops and agricultural food products.

5. The method of any one of claims 1 to 4, wherein the compound is applied in the form of a composition comprising one or more carriers, diluents or adjuvants, optionally agriculturally and food safety acceptable carriers, diluents or adjuvants.

6. The method of any one of claims 1 to 5, wherein the fungal pathogen belongs to a genus selected from Alternaria, Ascochyta, Aspergillus, Botrytis, Colletotrichum, Fusarium, Gaeumannomyces, Gibberella, Leptosphaeria, Magnaporthe, Mycosphaerella, Penicillium, Pythium, Phytophthora, Rhizoctonia, Sclerotinia, Ustilago, Verticillium, and Zymoseptoria.

7. The method of claim 6, wherein the pathogen is a Penicillium, Verticillium, Fusarium, Sclerotinia, Rhizoctonia or Zymoseptoria.

8. The method of any one of claims 1 to 7, wherein the compound or composition is applied via fumigation, optionally in a post-harvest facility.

9. The method of claim 8, wherein the post-harvest facility comprises a facility in which the crop or product is sorted, cleaned, stored, packed, transported, processed, or otherwise handled.

10. The method of any one of claims 1 to 9, wherein the application of the compound or composition prevents damage to the crop or product from post-harvest fungal disease caused by the fungal pathogen.

11. A method for protecting a harvested crop or agricultural food product from fungal pathogen infection or spoilage caused by a fungal pathogen, comprising applying to the harvested crop or agricultural food product, or to a facility in which the harvested crop or agricultural food product is sorted, cleaned, stored, packed, transported, processed or otherwise handled, a compound selected from tropone and a derivative or salt thereof, wherein where the compound is a derivative of tropone the derivative is a compound of Formula (I) or a salt thereofwherein:R1and R2are independently selected from the group consisting of alkyl, alkenyl, alkynyl, alkoxy, carboxyl, carbamoyl, acyl, aryl, heteroaryl, amino, alkylamino, cycloalkyl, cycloalkenyl, cycloalkynyl, heterocyclyl, halogen, cyano, nitro, NCS, SCN, alkylcarbonyl, alkylthiocarbonyl, alkoxycarbonyl and aminocarbonyl; and n is 0, 1, 2, 3 or 4.

12. The method of claim 11, wherein the compound is tropone.

13. The method of claim 11 or 12, wherein the crop or agricultural food product comprises fruits, vegetables, grain, cereals, nuts, oilseeds, or flowers or a product containing fruits, vegetables, grain, cereals, nuts, oilseeds, or flowers.

14. The method of any one of claims 11 to 13, wherein the method protects the crop or agricultural food product from spoilage caused by fungal pathogens and prolongs the shelf life of the harvested crop or agricultural food product.

15. The method of any one of claims 11 to 14, wherein the compound is applied in the form of a composition comprising one or more carriers, diluents or adjuvants, optionally agriculturally and food safety acceptable carriers, diluents or adjuvants.

16. The method of any one of claims 11 to 15, wherein the fungal pathogen belongs to a genus selected from Alternaria, Ascochyta, Aspergillus, Botrytis, Colletotrichum, Fusarium, Gaeumannomyces, Gibberella, Leptosphaeria, Magnaporthe, Mycosphaerella, Penicillium, Pythium, Phytophthora, Rhizoctonia, Sclerotinia, Ustilago, Verticillium, and Zymoseptoria.

17. The method of claim 16, wherein the pathogen is a Penicillium, Verticillium, Fusarium, Sclerotinia, Rhizoctonia or Zymoseptoria.

18. The method of any one of claims 11 to 17, wherein the compound or composition is applied via fumigation.

19. A method for inhibiting or preventing the growth of a fungus, comprising exposing the fungus, or a surface or environs on which the fungus grows or is capable of growing to a compound selected from tropone and a derivative or salt thereof, wherein where the compound is a derivative of tropone the derivative is a compound of Formula (I) or a salt thereofwherein:R1and R2are independently selected from the group consisting of alkyl, alkenyl, alkynyl, alkoxy, carboxyl, carbamoyl, acyl, aryl, heteroaryl, amino, alkylamino, cycloalkyl,cycloalkenyl, cycloalkynyl, heterocyclyl, halogen, cyano, nitro, NCS, SCN, alkylcarbonyl, alkylthiocarbonyl, alkoxycarbonyl and aminocarbonyl; and n is 0, 1, 2, 3 or 4.

20. A method for reducing susceptibility of a plant to a fungal infection, the method comprising applying to the plant or plant surrounds a compound selected from tropone and a derivative or salt thereof, wherein where the compound is a derivative of tropone the derivative is a compound of Formula (I) or a salt thereofwherein:R1and R2are independently selected from the group consisting of alkyl, alkenyl, alkynyl, alkoxy, carboxyl, carbamoyl, acyl, aryl, heteroaryl, amino, alkylamino, cycloalkyl, cycloalkenyl, cycloalkynyl, heterocyclyl, halogen, cyano, nitro, NCS, SCN, alkylcarbonyl, alkylthiocarbonyl, alkoxycarbonyl and aminocarbonyl; and n is 0, 1, 2, 3 or 4.

21. A method for treating or preventing a fungal pathogen infection of a plant, or for treating or preventing a fungal plant disease, the method comprising applying to the plant or plant surrounds a compound selected from tropone and a derivative or salt thereof, wherein where the compound is a derivative of tropone the derivative is a compound of Formula (I) or a salt thereofwherein:R1and R2are independently selected from the group consisting of alkyl, alkenyl, alkynyl, alkoxy, carboxyl, carbamoyl, acyl, aryl, heteroaryl, amino, alkylamino, cycloalkyl, cycloalkenyl, cycloalkynyl, heterocyclyl, halogen, cyano, nitro, NCS, SCN, alkylcarbonyl, alkylthiocarbonyl, alkoxycarbonyl and aminocarbonyl; and n is 0, 1, 2, 3 or 4.

22. The method of any one of claims 19 to 21, wherein the compound is tropone.

23. The method of any one of claims 19 to 22, wherein the compound is applied in the form of a composition comprising one or more carriers, diluents or adjuvants, optionally agriculturally and food safety acceptable carriers, diluents or adjuvants.

24. The method of any one of claims 19 to 23, wherein the fungus is a pathogen, more particularly a plant pathogen.

25. The method of claim 24, wherein the method comprises applying the compound to soil or other plant germination, propagation or growth media in which the plant is grown or is to be grown, plant surrounds or to one or more plant parts.

26. The method of claim 25, wherein the plant part comprises seed, roots, leaves, stems, flowers, fruit or nuts.

27. The method of any one of claims 19 to 26, wherein the fungus or fungal pathogen belongs to a genus selected from Alternaria, Ascochyta, Aspergillus, Botrytis, Colletotrichum, Fusarium, Gaeumannomyces, Gibberella, Leptosphaeria, Magnaporthe, Mycosphaerella, Penicillium, Pythium, Phytophthora, Rhizoctonia, Sclerotinia, Ustilago, Verticillium, and Zymoseptoria.

28. The method of claim 27, wherein the pathogen is a Penicillium, Verticillium, Fusarium, Sclerotinia, Rhizoctonia or Zymoseptoria.

29. The method of any one of claims 19 to 28, wherein the plant is a cereal crop, oilseed crop, grain crop, horticultural crop, or a crop for fibre production or ornamentals.

30. An antifungal composition comprising a compound selected from tropone and a derivative or salt thereof, optionally in combination with one or more one or more suitable carriers, diluents or adjuvants, optionally agriculturally acceptable carriers, diluents or adjuvants, wherein where the compound is a derivative of tropone the derivative is a compound of Formula (I) or a salt thereofwherein:R1and R2are independently selected from the group consisting of alkyl, alkenyl, alkynyl, alkoxy, carboxyl, carbamoyl, acyl, aryl, heteroaryl, amino, alkylamino, cycloalkyl, cycloalkenyl, cycloalkynyl, heterocyclyl, halogen, cyano, nitro, NCS, SCN, alkylcarbonyl, alkylthiocarbonyl, alkoxycarbonyl and aminocarbonyl; and n is 0, 1, 2, 3 or 4.

31. The antifungal composition of claim 30, wherein the compound is tropone.

32. A fumigant composition comprising a compound selected from tropone and a derivative or salt thereof, optionally in combination with one or more one or more suitable carriers, diluents or adjuvants, optionally agriculturally acceptable carriers, diluents or adjuvants, wherein where the compound is a derivative of tropone the derivative is a compound of Formula (I) or a salt thereofwherein:R1and R2are independently selected from the group consisting of alkyl, alkenyl, alkynyl, alkoxy, carboxyl, carbamoyl, acyl, aryl, heteroaryl, amino, alkylamino, cycloalkyl, cycloalkenyl, cycloalkynyl, heterocyclyl, halogen, cyano, nitro, NCS, SCN, alkylcarbonyl, alkylthiocarbonyl, alkoxycarbonyl and aminocarbonyl; and n is 0, 1, 2, 3 or 4.

33. The composition of claim 32, wherein the compound is tropone.

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