Method of controlling phytopathogenic fungi

Abstract

The present disclosure relates to a method of controlling or preventing phytopathogenic fungi belonging to Zymoseptoria tritici on a plant or on plant propagation material thereof, the method comprising applying to the plant, plant propagation material or locus thereof, a composition comprising a fungicidally effective amount of jawsamycin..

Description

[0001] METHOD OF CONTROLLING PHYTOPATHOGENIC FUNGI

[0002] The present invention relates to a method for controlling phytopathogenic fungi using jawsamycin.

[0003] Background

[0004] Jawsamycin is a natural compound, also indicated as FR-900848, that is produced by Streptoverticillium or Streptomyces bacteria. The compound was first discovered in 1990 by Yoshida et al (1990), J. of Antibiotics, p. 748-754. Yoshida et al (1990) discloses that the compound was active against some fungi from the division of Ascomycetes, such as Aspergillus niger, Aureobasidium, Penicillium chrysogenum,, Fusarium oxysporum, Sclerotinia arachidis and Trichophyton species, and a fungus from the division Mucoromycota Mucorrouxianaus,,

[0005] JP2101006 discloses that jawsamycin was active against apple leaf spot Alternaria and against cucumber Botrytis grey mold, which both belong to the division of Ascomycetes.

[0006] Fu et. al. (2020), Nature Communicationsl 1-3387 also discloses that jawsamycin was active against some yeasts, fungi such as Aspergillus sp., Fusarium oxysporum, Scedosporium sp, and some Mucorales fungi. Fu et al. (2020) suggests that jawsamycin would have a broad-spectrum fungicidal activity, however, there is no teaching or suggestion which fungi are affected by jawsamycin, nor if it would be active against fungal species on which plants.

[0007] Zymoseptoria tritici (Septoria tritici) is a widespread fungus that causes septoria tritici blotch, a foliar disease of wheat which poses a significant threat to global food production. Zymoseptoria tritici is a difficult fungus to control because Zymoseptoria tritici populations contain extremely high levels of genetic variability. In addition, resistance to known fungicides may develop easily, and therefore there is a need to continuously look for improved methods to control the disease. However, due to environmental and societal pressure agrochemical pesticides face more and more difficulty to get regulatory approval by the authorities. Accordingly, there is a need for improved methods to control phytopathogenic fungi such as Zymoseptoria tritici, preferably methods wherein a biological compound or natural product is applied.

[0008] Summary of the invention

[0009] The present invention relates to a method of controlling or preventing phytopathogenic fungi belonging to Zyomoseptoria tritici on a plant or on plant propagation material thereof, the method comprising applying to the plant, plant propagation material or locus thereof, a composition comprising jawsamycin. In another aspect the present invention relates to the use of jawsamycin for controlling or preventing phytopathogenic fungi, wherein the fungal species is Zymoseptoria tritici.

[0010] Surprisingly, it was found that Zymoseptoria tritici was effectively controlled by jawsamycin.

[0011] In another aspect the present invention relates to the use of jawsamycin for controlling or preventing phytopathogenic fungi, wherein the fungus comprises Zymoseptoria tritici. Detailed description

[0012] The present invention relates to a method of controlling or preventing phytopathogenic fungi belonging Zymoseptoria tritici on a plant or on plant propagation material thereof, the method comprising applying to the plant, plant propagation material or locus thereof, a composition comprising jawsamycin. Preferably, the composition comprises a fungicidally effective amount of jawsamycin.

[0013] The term “fungicidally effective amount” where used means the quantity of such a compound or combination of such compounds that is capable of producing an effect on the growth of fungi. Controlling or modifying effects include all deviation from natural development, such as killing, retardation and the like, and prevention includes barrier or other defensive formation in or on a plant to prevent fungal infection. Controlling or preventing means reducing infestation by phytopathogenic fungi to such a level that an improvement is demonstrated.

[0014] Surprisingly, it was found that Zymseptoria tritici (Septoria tritici) was effectively controlled by jawsamycin. To the contrary the phytopathogenic fungus Blumeria graminis, also an ascomycetes like Zymoseptoria was not affected by jawsamycin, nor the basidiomycetes Rhizoctonia insola and Puccinia recondite nor the oomycetes Pythium ultimum and Phytophthora infestans were controlled or affected by a composition comprising jawsamycin. Zymoseptoria tritici was surprisingly well controlled by jawsamycin on wheat, where Blumeria graminis, was not. Accordingly, it appears the teaching of Fu, Y. et al. in Nat Commun 11 , 3387 (2020) cannot be applied to all fungi. Zymoseptoria tritici was controlled at low rates of jawsamycin, preferably at an amount of 0.001 to 500 ppm, such as a rates of 0.005 to 400, such as a rate of 0.01 to 300 ppm, for instance a rate of 0.1 to 200 ppm. Accordingly, jawsamycin has a surprising fungicidal activity against Zymoseptoria tritici.

[0015] Zymoseptoria tritici is an ascomycete in the family Mycosphaerellaceae, whereas Blumeria graminis is an ascomycete in the family Erysiphales

[0016] Jawsamycin is a known compound and has a structural formula according to Formula (la)

[0017] The jawsamycin of formula (la) is an oligocyclopropyl-containing natural product, also noted as FR- 900848. Jawsamycin is a polyketide comprising a 5'-amino-5'-deoxy-3,4,5,6-tetrahydrouridine in which one of the hydrogens of the amino group is substituted by a (1 E,3E)-1- [(1 R, 1 'R, 1 "R,1 "'R,2S,2'R,2"R,2"'S)-2"'-{(E)-2-[(1 R,2R)-2-methylcyclopropyl] quater(cyclopropan)]-2-yl]-5-oxopenta-1 ,3-dien-5-yl group.

[0018] The structure of jawsamycin is C32H43N3O6, comprising a 5'-amino-5'-deoxy-5, 6-dihydrouridine with an unsaturated fatty acid comprising four serial and one isolated cyclopropane rings.

[0019] Its IUPAC name of jawsamycin is (2E,4E)-N-[[(2R,3S,4R,5R)-5-(2,4-dioxo-1 ,3-diazinan-1-yl)-3,4- dihydroxyoxolan-2-yl]methyl]-5-[(1 S,2R)-2-[(1 R,2R)-2-[(1 R,2R)-2-[(1 R,2S)-2-[(E)-2-[(1 R,2R)-2- methylcyclopropyl]ethenyl]cyclopropyl]cyclopropyl]cyclopropyl]cyclopropyl]penta-2,4-dienamide.

[0020] While the total synthesis of jawsamycin entitled “pentacyclopropane antifungal agent FR-900848” has been disclosed by A. Barrett et al., J. Am. Chem. Soc. 1996, 118, 45, 11030-11037, the compound is preferably accessible, and employed, as the metabolite obtained from, or isolated from Streptoverticillium or Streptomyces bacteria.

[0021] A microorganism expressing a compound according to formula (la) may be a Streptoverticillium and / or a Streptomyces, preferably Streptoverticillium fervens, and / or Streptomyces luteoverticillatus, or their spores, as these microorganisms express the compounds of formula (la) as metabolites.

[0022] A particularly suitable route to produce jawsamycin may be by cultivating Streptoverticillium fervens and isolating jawsamycin, for instance according to the methods disclosed in Masaru et al, The Journal of Antibiotics, 1990, Volume 43, Issue 7, Pages 748-754.

[0023] Congeners of jawsamycin are compounds lb and Ic according to following formulae:

[0024] These congeners according to formula lb) and Ic) are expressed by the above microbial cultures in varying, but usually small or negligible amounts.

[0025] The method according to the present invention comprises applying a composition comprising Jawsamycin to a plant, plant propagation material or locus thereof. Applying jawsamycin to a plant may be performed by spraying, dusting or any suitable other means. A suitable method of controlling or preventing an infestation of crop plants Zymoseptoria tritici comprises the application of an agrochemical composition comprising jawsamycin is foliar application. The frequency of application and the rate of application will depend on the risk of infestation by Zymoseptoria tritici. However, jawsamycin can also penetrate the plant through the roots via the soil by drenching the locus of the plant with a liquid formulation, or by applying the compounds in solid form to the soil, e.g. in granular form (soil application).

[0026] It may be possible to use a composition comprising jawsamycin as dressing agents for the treatment of plant propagation material, e.g., seed, such as fruits, tubers or grains, or plant cuttings, for the protection against infections by Zymoseptoria tritici, occurring in the soil. The propagation material can be treated with a composition comprising jawsamcying before planting: seed, for example, can be dressed before being sown. Jawsamycin can also be applied to grains (coating), either by impregnating the seeds in a liquid formulation or by coating them with a solid formulation. The composition can also be applied to the planting site when the propagation material is being planted, for example, to the seed furrow during sowing.

[0027] The method according to the present invention comprises applying compositions, wherein the composition may be employed in any conventional form, for example in the form of a twin pack, a powder for dry seed treatment (DS), an emulsion for seed treatment (ES), a flowable concentrate for seed treatment (FS), a solution for seed treatment (LS), a water dispersible powder for seed treatment (WS), a capsule suspension for seed treatment (CF), a gel for seed treatment (GF), an emulsion concentrate (EC), a suspension concentrate (SC), a suspo-emulsion (SE), a capsule suspension (CS), a water dispersible granule (WG), an emulsifiable granule (EG), an emulsion, water in oil (EG), an emulsion, oil in water (EW), a micro-emulsion (ME), an oil dispersion (OD), an oil miscible flowable (OF), an oil miscible liquid (OL), a soluble concentrate (SL), an ultra-low volume suspension (SU), an ultra-low volume liquid (UL), a technical concentrate (TK), a dispersible concentrate (DC), a wettable powder (WP) or any technically feasible formulation in combination with agriculturally acceptable adjuvants. Such compositions may be produced in conventional manner, e.g., by mixing the active ingredients with at least one appropriate inert formulation adjuvant (for example, diluents, solvents, fillers, and optionally other formulating ingredients such as surfactants, biocides, anti-freeze, stickers, thickeners, and compounds that provide adjuvancy effects). Also, conventional slow-release formulations may be employed where long lasting efficacy is intended. Particularly formulations to be applied in spraying forms, such as water dispersible concentrates (e.g. EC, SC, DC, OD, SE, EW, EO and the like), wettable powders and granules, may contain surfactants such as wetting and dispersing agents and other compounds that provide adjuvancy effects, e.g. the condensation product of formaldehyde with naphthalene sulphonate, an alkylarylsulphonate, a lignin sulphonate, a fatty alkyl sulphate, and ethoxylated alkylphenol and an ethoxylated fatty alcohol.

[0028] Any suitable plant may be treated to prevent or control infestation by Zymoseptoria tritici (Septoria tritici). A suitable plant comprises cereals for example barley, maize (corn), millet, oats, rice, rye, sorghum triticale and wheat. Preferably, the plant comprises or is wheat. The term “plants” refers to all physical parts of a plant, including seeds, seedlings, saplings, roots, tubers, stems, stalks, foliage, and fruits.

[0029] A plant as used herein also includes useful plants. The term "useful plants" is to be understood as also including useful plants that have been rendered tolerant to herbicides.

[0030] The term "useful plants" is to be understood as also including useful plants which have been so transformed by the use of recombinant DNA techniques that they are capable of synthesizing one or more selectively acting toxins, such as are known, for example, from toxin-producing bacteria, especially those of the genus Bacillus.

[0031] The term “plant propagation material” is understood to denote generative parts of the plant, such as seeds, which can be used for the multiplication of the latter, and vegetative material, such as cuttings or tubers, for example potatoes. There can be mentioned for example seeds (in the strict sense), roots, fruits, tubers, bulbs, rhizomes and parts of plants. Germinated plants and young plants which are to be transplanted after germination or after emergence from the soil, may also be mentioned. These young plants can be protected before transplantation by a total or partial treatment by immersion. Preferably “plant propagation material” is understood to denote seeds.

[0032] The term “locus” as used herein means fields in or on which plants are growing, or where seeds of cultivated plants are sown, or where seed will be placed into the soil. It includes soil, seeds, and seedlings, as well as established vegetation.

[0033] Throughout this document the expression “composition” stands for the various mixtures or combinations of jawsamycin, for example in a single “ready-mix” form, in a combined spray mixture composed from separate formulations of the single active ingredient components, such as a “tank-mix”, and in a combined use of the single active ingredients when applied in a sequential manner, i.e. one after the other with a reasonably short period, such as a few hours or days.

[0034] The composition comprising jawsamycin in a method according to the present invention preferably is an agriculturally acceptable composition. Preferably, the composition further comprises at least one agriculturally acceptable carrier, additive, formulation adjuvant, and / or a surfactant.

[0035] Suitable carriers and adjuvants, e.g. for agricultural use, can be solid or liquid and are substances useful in formulation technology, e.g. natural or regenerated mineral substances, solvents, dispersants, wetting agents, tackifiers, thickeners, binders or fertilizers.

[0036] In another embodiment, the composition comprises one or more further biologically active compound(s), preferably one or more further pesticide, such as fungicides, insecticides, or herbicides.

[0037] Such one or more further pesticidal components are known and are referred to hereinabove by their so-called ISO common name or their IUPAC name. Typical pesticidal components are included in the Pesticide Manual Online ("E-pesticide Manual") by the British Crop Production Council and in the Compendium of Pesticide Common Names by Alan Wood.

[0038] In one embodiment of method according to the present invention, jawsamycin is applied at a rate of from 5 to 2000 g a.i. / ha, particulary 1 g a.i. / ha to 1000 g a.i. I ha, preferably at a rate 5 g a.i. / ha to 500 g a.i. / ha, preferably at a rate 1 g a.i. / ha to 250 g a.i. / ha. As used herein, the abbreviation “a.i.” stands for “active ingredient”, and the active ingredient herein comprises or is jawsamycin,

[0039] In another embodiment of the method according to the present invention jawsamycin is applied at a rate of, 0.001 to 50 g of a.i. per kg of plant propagation material, in particular per kg of seeds. Preferably, jawsamycin is applied at a rate of, 0.01 to 40 g, preferably at a rate of 0.1 to 30 g of a.i. per kg of plant propagation material.

[0040] The present invention also relates to the use of jawsamycin for controlling or preventing phytopathogenic fungi, wherein the fungal species comprises or is Zymoseptoria tritici. In particular, said use is effective for controlling or preventing Zymoseptoria tritici on a plant or on plant propagation material thereof.

[0041] The method and use of the present invention excludes methods and uses for the treatment of the human or animal body by surgery or therapy.

[0042] Examples

[0043] Materials and methods

[0044] Jawsamycin employed in the examples was produced by cultivating Streptoverticillium fervens and isolating jawsamycin according to the methods disclosed in Masaru et al, The Journal of Antibiotics, 1990, Volume 43, Issue 7, Pages 748-754.

[0045] Example 1. Efficacy of Jawsamycin against Zymoseptoria tritici, Pythium ultimum and Rhizoctonia solani

[0046] Methodology in v / fro well based liquid culture assay

[0047] Conidia of the fungus Pythium ultimum, Zymoseptoria tritici and Rhizoctonia solani from cryogenic storage were directly mixed into nutrient broth (PDB potato dextrose broth). After placing a (DMSO) solution of the test compounds into a microtiter plate (96-well format) the nutrient broth containing the fungal spores was added. The test plates were incubated at 24 °C and the inhibition of growth was determined photometrically at 620nm after two to four days.

[0048] Table 1. Efficacy of jawsamycin (%) against Pythium ultimum, Zymoseptoria tritici and Rhizoctonia solani in in vitro well based liquid culture assay Example 2: Efficacy of jawsamycin against Zymoseptoria tritici (syn. Mycosphaerella graminicola) on wheat with a preventative application.

[0049] 2-week old wheat plants cv. Riband were sprayed in a spray chamber with the formulated test compound diluted in water. The test plants were inoculated by spraying a spore suspension on them one day after application. After an incubation period of 1 day at 22°C / 21 °C (day / night) and 95% rh, the inoculated test plants are kept at 22°C / 21°C (day / night) and 70% rh in a greenhouse. Efficacy was assessed directly when an appropriate level of disease appeared on untreated check plants (16 - 19 days after application).

[0050] Comparative examples

[0051] Blumeria graminis f. sp. tritici (Erysiphe graminis f. sp. tritici) on wheat with a preventative application.

[0052] 1-week old wheat plants cv. Arina were sprayed in a spray chamber with the formulated test compound diluted in water. The test plants were inoculated by spreading powdery mildew spores over them in an inoculation chamber two days after application. The inoculated test plants were incubated at 20° C 1 18°C (day / night) and 60% rh in a greenhouse and the percentage leaf area covered by disease was assessed when an appropriate level of disease appeared on untreated check plants (7 - 9 days after application).

[0053] Phytophthora infestans on potato with a preventative application.

[0054] 2-week old potato plants cv. Bintje were sprayed in a spray chamber with the formulated test compound diluted in water. The test plants were inoculated by spraying them with a sporangia suspension 2 days after application. The inoculated test plants were incubated at 18° C with 14 h light / day and 100 % rh in a growth chamber and the percentage leaf area covered by disease was assessed when an appropriate level of disease appeared on untreated check plants (5 - 7 days after application).

[0055] Plasmopara viticola on grape with a preventative application

[0056] 5-week old grape seedlings cv. Gutedel were sprayed in a spray chamber with the formulated test compound diluted in water. The test plants plants were inoculated by spraying a sporangia suspension on their lower leaf surface one day after application. The inoculated test plants were incubated at 22° C and 100% rh in a greenhouse and the percentage leaf area covered by disease was assessed when an appropriate level of disease appeared on untreated check plants (6 - 8 days after application).

[0057] Puccinia recondita f. sp. tritici on wheat with a preventative application

[0058] 2-week old wheat plants cv. Arina were sprayed in a spray chamber with the formulated test compound diluted in water. The test plants were inoculated by spraying them with a spore suspension one day after application. After an incubation period of 1 day at 20° C and 95% rh, the inoculated test plants were kept at 20° C / 18° C (day / night) and 60% rh in a greenhouse. The percentage leaf area covered by disease was assessed when an appropriate level of disease appeared on untreated check plants (12 - 14 days after application). Table 2. Efficacy (%) of jawsamycin against Zymoseptoria tritici on wheat compared to oocymetes Phytophthora infestans and Plasmopora viticola, the ascomycete Blumeria graminis and basidiomycete Puccinia recondite on several plants Conclusion

[0059] The results in Examples 1 and 2 show that jawsamycin has efficient fungicidal activity against the phytopathogenic fungus Zymoseptoria tritici, both in vitro and on planta.

Claims

Claims1 . A method of controlling or preventing phytopathogenic fungi belonging to Zymoseptoria tritici on a plant or on plant propagation material thereof, the method comprising applying to the plant, plant propagation material or locus thereof, a composition comprising jawsamycin.

2. The method according to claim 1 , wherein the composition comprises a fungicidally effective amount of jawsamycin.

3. The method according to claim 1 or 2, wherein the plant is selected from cereals selected from barley, maize (corn), millet, oats, rice, rye, sorghum triticale and wheat, preferably the plant is wheat.

4. The method according to any one of the claims 1 to 3, wherein the composition is an agriculturally acceptable composition.

5. The method according to claim 4, wherein the composition further comprises at least one agriculturally acceptable carrier, additive, formulation adjuvant, and / or a surfactant.

6. The method according to any one of the claims 1 to 5, wherein the composition comprises one or more further biologically active compound(s), preferably one or more further pesticide, such as fungicides, insecticides, or herbicides.

7. The method according to any one of the claims 1 to 6, wherein the fungicidally effective amount of jawsamycin comprises 5 g a.i. / ha to 2000 g a.i. I ha.

8. The method according to any one of claims 1 to 6, wherein the fungicidally effective amount of jawsamycim comprises 0.001 to 50 g of a.i. per kg of plant propagation material, preferably per kg of seeds.

9. Use of jawsamycin for controlling or preventing phytopathogenic fungi, wherein the fungus comprises Zymoseptoria tritici.

10. Use according to claim 9, wherein said controlling or preventing phytopathogenic fungi is on a plant or on plant propagation material.

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