Composition and method for inhibiting growth of phytopathogen

Abstract

The purpose of the present invention is to provide a composition and a method useful for inhibiting the growth of a phytopathogen.　The present invention provides a composition for phytopathogen growth inhibition, the composition containing mercaptopropionic acid. The present invention also provides a method for inhibiting the growth of a phytopathogen, the method including a step for bringing mercaptopropionic acid into contact with a phytopathogen.

Description

Compositions and methods for inhibiting the growth of plant pathogens

[0001] The present invention relates to a composition and method for inhibiting the growth of plant pathogenic fungi, more specifically, to a composition for inhibiting the growth of plant pathogenic fungi containing mercaptopropionic acid as an active ingredient, and to a method for inhibiting the growth of plant pathogenic fungi using mercaptopropionic acid.

[0002] Approximately one-quarter of the world's crops are lost to pests and pathogens, and approximately 60% of these are caused by underground diseases, i.e., soil-borne diseases. Soil-borne diseases caused by plant pathogens are difficult to control and cause enormous damage in crop production sites.

[0003] Currently, the compounds used to control soil diseases are extremely limited. Methyl bromide was used in the past, but its complete abolition was decided under the Montreal Protocol, forcing a transition to alternative technologies. Currently, chloropicrin is formulated as the main pesticide (soil fumigant), but this compound is designated as a deleterious substance, raising concerns about its environmental impact. Soil disinfection using ethanol has been developed as an alternative technology, but its effectiveness is limited.

[0004] Furthermore, when protecting plants, it is necessary to take preventative measures against not only soil-borne diseases but also above-ground diseases. The majority of above-ground plant diseases are airborne, and control techniques that can limit the spread of damage in the field are needed. Aerial spraying is an effective method of controlling above-ground diseases, but due to concerns about the environmental impact of spraying, the types of pesticides that can be used are limited, and it is desirable to use appropriate pesticides at the appropriate time. Furthermore, there are only a limited number of cases where pesticides that are effective in controlling soil-borne diseases are also used to control above-ground diseases.

[0005] Meanwhile, mercaptopropionic acid has been previously disclosed for use in combination with bismuth as a disinfectant for biomedical applications, including the treatment of bacterial biofilms and other uses (Patent Document 1). However, this technology is a medical technology and is not related to plant protection effects. Furthermore, this technology only lists mercaptopropionic acid as an example of a thiol compound, and does not disclose its specific effects.

[0006] Japanese Patent Application Laid-Open No. 2018-76358

[0007] As described above, currently, there are only a limited number of effective agents for suppressing pathogens that cause plant diseases such as soil-borne diseases and above-ground diseases. Therefore, an object of the present invention is to provide a composition or method useful for suppressing the growth of plant pathogens.

[0008] As a result of intensive research to achieve the above object, the present inventors have focused on mercaptopropionic acid among various compounds and found that mercaptopropionic acid has a significant growth inhibitory effect on plant pathogenic fungi. Based on this finding, the present inventors have completed the present invention.

[0009] The present invention is preferably carried out in the following embodiments, but is not limited thereto. [Embodiment 1] A composition for inhibiting the growth of plant pathogens, comprising mercaptopropionic acid. [Embodiment 2] The composition according to embodiment 1, wherein the plant pathogens are plant pathogens that cause soil-borne diseases or above-ground diseases. [Embodiment 3] A method for inhibiting the growth of plant pathogens, comprising the step of contacting plant pathogens with mercaptopropionic acid. [Embodiment 4] The method according to embodiment 3, wherein the plant pathogens are plant pathogens that cause soil-borne diseases or above-ground diseases.

[0010] By utilizing the present invention, it is possible to provide a composition or method useful for inhibiting the growth of plant pathogens. Furthermore, by using the technology of the present invention, it is possible to protect plants from disease. Because the technology of the present invention is effective against plant pathogens that cause soil-borne diseases, it is possible to effectively protect plants from soil-borne diseases by using the composition or method of the present invention. Furthermore, because the technology of the present invention is effective against plant pathogens that cause above-ground diseases, it is possible to effectively protect plants from above-ground diseases by using the composition or method of the present invention.

[0011] FIG. 1 is a graph showing the results of investigating the antibacterial activity (growth inhibitory activity) of mercaptopropionic acid against Pythium spp. FIG. 2 is a graph showing the distance from filter paper impregnated with mercaptopropionic acid to the hyphal tips of Pythium spp. FIG. 3 is a graph showing the effect of volatility of mercaptopropionic acid in an antibacterial test. FIG. 4 is a graph showing the results of investigating the antibacterial activity (growth inhibitory activity) of mercaptopropionic acid against Fusarium spp. FIG. 5 is a graph showing the results of investigating the antibacterial activity (growth inhibitory activity) of mercaptopropionic acid against Ralstonia spp. FIG. 6 is a graph showing the results of investigating the effective concentration of mercaptopropionic acid against Pythium spp. FIG. 7 is a graph showing the results of investigating the effective concentration of mercaptopropionic acid against Ralstonia spp. FIG. 8 is a graph showing the change in the number of surviving cucumbers over time. Fig. 9 is a diagram showing the growth status of cucumber seedlings as a result of investigating the effect of mercaptopropionic acid on cucumber disease. Fig. 10 is a diagram showing the incidence of bacterial wilt, a soil-borne disease, on tomato leaves. Fig. 11 is a diagram showing the growth status of tomatoes two days after inoculation with Ralstonia bacteria as a result of investigating the effect of mercaptopropionic acid on tomato disease. Fig. 12 is a diagram showing the growth status of cucumbers seven days after inoculation with anthracnose, a part-borne disease, as a result of investigating the effect of mercaptopropionic acid on cucumber disease. Fig. 13 is a diagram showing the growth status of cucumbers 11 days after inoculation with anthracnose, a part-borne disease, as a result of investigating the effect of mercaptopropionic acid on cucumber disease.

[0012] The present invention will be described in detail below, but the present invention is not limited thereto. Unless otherwise defined herein, scientific and technical terms used in connection with the present invention have the meanings that are commonly understood by those skilled in the art.

[0013] (1) Composition for inhibiting the growth of plant pathogenic fungi One aspect of the present invention is a composition for inhibiting the growth of plant pathogenic fungi, which contains mercaptopropionic acid.

[0014] Mercaptopropionic acid can be contained as an active ingredient in the composition of the present invention. The mercaptopropionic acid used in the present invention is preferably 3-mercaptopropionic acid. 3-mercaptopropionic acid has the molecular formula C ３ H ６ O ２ It is a compound represented by the formula S, and its CAS registry number is 107-96-0. 3-Mercaptopropionic acid is known to be used as a metal masking agent and a reducing agent.

[0015] The content of mercaptopropionic acid in the composition of the present invention is not particularly limited and may be at a level that can inhibit the growth of plant pathogens. The content can be appropriately set depending on the type of plant pathogen to be targeted.

[0016] Although not particularly limited, the content of mercaptopropionic acid in the composition of the present invention, as a concentration at time of use (final concentration), is, for example, 1 μM or more, preferably 10 μM or more, more preferably 0.1 mM or more, 0.2 mM or more, or 0.5 mM or more, even more preferably 1 mM or more, 2 mM or more, or 5 mM or more. Furthermore, the content of mercaptopropionic acid in the composition of the present invention, as a concentration at time of use, is, for example, 10 M or less, preferably 1 M or less, more preferably 100 mM or less, even more preferably 10 mM or less. The content of mercaptopropionic acid in the composition of the present invention, as a concentration at time of use, is typically, for example, 1 μM to 10 M, preferably 10 μM to 1 M, more preferably 0.1 mM to 100 mM, even more preferably 1 mM to 10 mM. The content of mercaptopropionic acid in the composition of the present invention can be measured using HPLC or the like.

[0017] When the composition of the present invention is a liquid, it can be in the form of a concentrated solution, and the concentration ratio is, for example, 10 times, 20 times, 50 times, 100 times, 200 times, 500 times, 1000 times, 2000 times, 5000 times, or 10000 times the concentration at the time of use. The concentration ratio can be, for example, 10 to 10000 times, preferably 50 to 10000 times, more preferably 100 to 10000 times, and even more preferably 1000 to 10000 times the concentration at the time of use. When the composition of the present invention is in the form of a concentrated solution, it can be used after being appropriately diluted with a liquid such as water.

[0018] The composition of the present invention may also be a solid formulation. When the composition of the present invention is in the form of a solid formulation, the content of mercaptopropionic acid in the composition can be adjusted to, for example, 100 times, 200 times, 500 times, 1000 times, 10,000 times, or 100,000 times the concentration at the time of use. When the composition of the present invention is in the form of a solid formulation, the content of mercaptopropionic acid in the composition can be, for example, 100 to 100,000 times, preferably 200 to 100,000 times, more preferably 500 to 100,000 times, and even more preferably 1,000 to 100,000 times the concentration at the time of use. When the composition of the present invention is in the form of a solid formulation, it can be dissolved or dispersed appropriately in a liquid such as water before use.

[0019] The amount of mercaptopropionic acid used in the composition of the present invention is not particularly limited, and can be appropriately determined depending on the application form, the type of target plant pathogen, etc. For example, when the composition of the present invention is used in soil, the concentration (amount used) of mercaptopropionic acid is not particularly limited, but ３ The concentration can be adjusted to 1 μM or more, preferably 10 μM or more, more preferably 0.1 mM or more, 0.2 mM or more, or 0.5 mM or more, and even more preferably 1 mM or more, 2 mM or more, or 5 mM or more per 1 cm of soil. ３ The concentration (amount used) of mercaptopropionic acid can be adjusted to 10 M or less, preferably 1 M or less, more preferably 100 mM or less, and even more preferably 10 mM or less per application to the soil. When the composition of the present invention is applied to soil, the concentration (amount used) of mercaptopropionic acid is typically, for example, 1 μM to 10 M, preferably 10 μM to 1 M, more preferably 0.1 mM to 100 mM, and even more preferably 1 mM to 10 mM.

[0020] When the composition of the present invention is applied to plants, the concentration (amount used) of mercaptopropionic acid is not particularly limited, but can be adjusted to 1 μM or more, preferably 10 μM or more, more preferably 0.1 mM or more, 0.2 mM or more, or 0.5 mM or more, and even more preferably 1 mM or more, 2 mM or more, or 5 mM or more per plant per application. The upper limit of the concentration (amount used) is not particularly limited, but can be adjusted to 10 M or less, preferably 1 M or less, more preferably 100 mM or less, and even more preferably 10 mM or less per plant per application. When the composition of the present invention is applied to plants, the concentration (amount used) of mercaptopropionic acid is typically, for example, 1 μM to 10 M, preferably 10 μM to 1 M, more preferably 0.1 mM to 100 mM, and even more preferably 1 mM to 10 mM.

[0021] The mercaptopropionic acid used in the present invention may be chemically synthesized or obtained from a natural product. Mercaptopropionic acid may be synthesized or purified by a method known to those skilled in the art, or may be commercially available. In the present invention, commercially available mercaptopropionic acid is preferably used.

[0022] Mercaptopropionic acid may also be a product of a microorganism. That is, the mercaptopropionic acid used in the present invention may be derived from a microorganism. Examples of microbial products include metabolic products, which may be primary or secondary metabolic products. Microorganisms that produce mercaptopropionic acid include bacteria, specifically bacteria of the genus Pseudomonas. Pseudomonas bacteria belong to the family Pseudomonadaceae in the class Gammaproteobacteria of the phylum Proteobacteria, and are characterized as gram-negative aerobic rods. Specific examples of Pseudomonas bacteria include, but are not limited to, Pseudomonas protegens and Pseudomonas aeruginosa.

[0023] The composition of the present invention is applied to plant pathogens. The "plant pathogens" described herein are not limited to bacteria and fungi, but refer to microorganisms that cause plant diseases (also referred to as "plant pathogenic microorganisms"). In the present invention, plant pathogens may be either bacteria or fungi. The plant pathogens to which the composition of the present invention is applied are not particularly limited, but are preferably plant pathogens that cause soil-borne diseases or above-ground diseases (diseases of the above-ground parts of plants). In this specification, above-ground diseases refer to diseases that occur in parts of the plant that are above ground (including parts that are not in contact with the ground).

[0024] Soil-borne diseases are often caused by pathogenic microorganisms that live in the soil, such as bacteria and fungi, and fungi include filamentous fungi (including oomycetes). Specific examples of filamentous fungi that are pathogenic microorganisms include the genus Pythium (Pythium ultimum, Pythium aphanidermatum, Pythium megalacanthum, etc.), the genus Fusarium (Fusarium oxysporum, Fusarium graminearum, Fusarium solani, etc.), the genus Rhizoctonia (Rhizoctonia solani, etc.), ... Pythium (Pythium ultimum, Pythium aphanidermatum, Pythium megalacanthum, etc.), the genus Pythium (Pythium ultimum, Pythium aphanidermatum, Pythium megalacanthum, etc.), the genus Pythium (Pythium ultimum, Pythium aphanidermatum, Pythium megalacanthum, etc.), the genus Pythium (Pythium ultimum, Pythium ultimum, Pythium megalacanthum, etc.), the genus Pythium (Pythium ultimum, Pythium ultimum, Pythium megalacanthum, etc.), the genus Pythium (Pythium ultimum, Pythium ultimum, Pythium megalacanthum, etc.), the genus Pythium (Pythium solani, etc.), and the genus Thielaviopsis. Specific examples of pathogenic microorganisms other than filamentous fungi include bacteria of the genus Erwinia (Erwinia carotovora, etc.), bacteria of the genus Ralstonia (Ralstonia solanacearum, etc.), bacteria of the genus Pectobacterium (Pectobacterium carotovorum, etc.), bacteria of the genus Burkholderia (Burkholderia glumae, etc.), and bacteria of the genus Agrobacterium (Agrobacterium tumefaciens (Agrobacterium tumefaciens, etc.).

[0025] Examples of soil-borne diseases include seedling damping-off, Pythium rot, bacterial wilt, root rot of transplanted seedlings, wilt, leaf rot, root rot, vine splitting, damping-off, yellowing, bottom rot, root rot weakening, cone browning, rot, leaf blight, dry rot, stem blight, red mold, bulb rot, stem rot wilt, stem rot, root rot wilt, black-streaked fruit rot, semi-blight, black spot, Panama disease, brown rot, Fusarium wilt, stem rot, and sheath blight. , bud blight, spider blight, brown sheath blight, bottom rot, Rhizoctonia, corm rot, black smear, hole leaf blight, dry root rot, large-grain white blight, tiger spot, bottom rot, fruit rot, waist break, forest root rot, butt rot, pod rot, skin rot, brown smear, root rot, brown spot, white leaf rot, Rhizoctonia leaf sheath rot, Rhizoctonia root rot, hydroponic seedling root rot, etc., but are not limited to these.

[0026] Pathogenic microorganisms that cause above-ground plant diseases include, for example, bacteria and fungi. Examples of fungi include fungi of the genus Colletotrichum (such as Colletotrichum orbiculare, Colletotrichum gloeosporioides, and Colletotrichum acutatum), fungi of the genus Botrytis (such as Botrytis cinerea), and fungi of the genus Sphaerotheca (such as Sphaerotheca fuliginea). fuliginea, etc.), Peronospora genus (Peronospora parasitica, etc.), Pseudoperonospora genus (Pseudoperonospora cubensis, etc.), Pythium genus (Pythium ultimum, Pythium aphanidermatum, Pythium megalacanthum, etc.), Fusarium genus (Fusarium Examples of fungi that can be used include fungi of the genus Fusarium oxysporum (Fusarium oxysporum), Fusarium graminearum, Fusarium solani, etc.), fungi of the genus Rhizoctonia (Rhizoctonia solani, etc.), and fungi of the genus Thielaviopsis.

[0027] Specific examples of pathogenic bacteria that cause above-ground plant diseases include bacteria of the genus Pseudomonas (e.g., Pseudomonas syringae), bacteria of the genus Xanthomonas (e.g., Xanthomonas campestris), bacteria of the genus Erwinia (e.g., Erwinia amylovora, Erwinia carotovora), bacteria of the genus Clavibacter (e.g., Clavibacter michiganensis), bacteria of the genus Pseudomonas (e.g., Pseudomonas syringae), bacteria of the genus Xanthomonas (e.g., Xanthomonas campestris), bacteria of the genus Erwinia (e.g., Erwinia amylovora, Erwinia carotovora), bacteria of the genus Clavibacter (e.g., Clavibacter michiganensis), bacteria of the genus Pseudomonas (e.g., Pseudomonas spp. ... Examples of bacteria that can be used include bacteria of the genus Ralstonia (e.g., Ralstonia solanacearum), bacteria of the genus Pectobacterium (e.g., Pectobacterium carotovorum), bacteria of the genus Burkholderia (e.g., Burkholderia glumae), and bacteria of the genus Agrobacterium (e.g., Agrobacterium tumefaciens).

[0028] Examples of above-ground plant diseases include anthracnose, gray mold, leaf mold, downy mildew, bacterial spot, leaf spot, wildfire, bacterial hole, black rot, fire blight, wilt, leaf rot, vine splitting, damping-off, yellowing, bottom rot, rot, leaf blight, dry rot, stem blight, Fusarium head blight, stem rot, black-streaked fruit rot, semi-blight, black spot, Panama disease, brown rot, and fuza. Examples of diseases that can be caused by this disease include, but are not limited to, rhizoctonia blight, foot rot, sheath blight, bud blight, spider blight, brown sheath blight, bottom rot, Rhizoctonia blight, corm rot, black spot, hole leaf blight, large-grain white blight, tiger spot, bottom rot, fruit rot, waist break, forest root rot, bottom rot, pod rot, skin rot, brown spot, brown spot, white leaf rot, and Rhizoctonia leaf sheath rot.

[0029] The plants targeted in the present invention are not particularly limited, but are preferably agricultural crops. Examples of agricultural crops include, but are not limited to, vegetables, grains, fruits, flowers, and legumes. Specific examples include melons (cucumber, watermelon, pumpkin, zucchini, gourd, loofah, wax gourd, Easter melon, bottle gourd, bitter melon (bitter melon, bitter gourd), melon, etc.), tubers (potato, sweet potato, taro, Chinese yam, Chinese yam, etc.), root vegetables (turnip, radish, Chinese radish, wasabi, horseradish, burdock, Chinese artichoke, ginger, carrot, scallion, lotus root, lily root, etc.), leafy vegetables (cabbage, cucumber ... Lacina, cabbage, watercress, kale (hagoromokaranran), komatsuna, Chinese mustard greens, lettuce, Shandong cabbage, chrysanthemum, shirona, Japanese parsley, celery, tatsoi, daikon radish (suzushiro), takana, bok choy, chives, rape blossoms, nozawana, Chinese cabbage, parsley, haruna, Swiss chard, spinach, mizuna, mibuna, mitsuba, Brussels sprouts, arugula, lettuce (lettuce), hanaccoli, wasabi, etc.), fruit vegetables (eggplant, pepino, tomato Tomatoes (cherry tomatoes, fruit tomatoes, etc.), tamarillo, Takanotsume, chili peppers, shishito peppers, habanero, bell peppers (including paprika and colored peppers), pumpkin, zucchini, cucumber, horned bitter melon (kiwano), white cucumber, bitter melon (bitter melon, bitter gourd), wax gourd, loofah, bottle gourd, okra, etc.), grains (corn, etc.), legumes (adzuki beans, kidney beans, peas, edamame (green soybeans), cowpeas, winged beans, broad beans, soybeans, sword beans, peanuts, lentils, sesame, etc.), fungi (enokitake, king oyster mushroom, wood ear mushroom, shiitake, shimeji, white fungus, Tamogitake, Nichitake, nameko, armillaria, hatakeshimeji, oyster mushroom, buna-shimeji, bunapi, porcini, hon-shimeji, maitake, mushroom, matsutake, Yamabushitake, etc.), fruits (tangerines, strawberries, apples, pears, bananas, peaches, cherries, grapes, etc.), etc.

[0030] In addition to mercaptopropionic acid, the composition of the present invention may contain additives such as excipients, thickeners, binders, stabilizers, preservatives, pH adjusters, colorants, and flavoring agents. The various additives are not particularly limited, and materials known in the agricultural chemicals technical field can be used, and the amount of each additive can be appropriately adjusted based on the techniques known to those skilled in the art. Furthermore, the form of the composition of the present invention may be any of liquid, solid, gel, paste, etc., and can be appropriately selected depending on the usage situation, etc. When the composition of the present invention is a liquid, it can also be used as a spray-type liquid formulation.

[0031] The composition of the present invention can be used as, but is not particularly limited to, a pesticide. Therefore, the composition of the present invention may be a pesticide composition. The composition of the present invention may also be referred to as an agent, and the composition for inhibiting plant pathogen growth of the present invention may be referred to as a plant pathogen growth inhibitor.

[0032] The composition of the present invention is characterized by having an inhibitory effect on the growth of plant pathogens, and based on this effect, it is possible to prevent plant diseases and protect plant growth. Therefore, the composition of the present invention can be used for plant disease control or plant protection (more specifically, for protecting plant growth). As described above, the plant disease is preferably a soil-borne disease.

[0033] (2) Method for inhibiting the growth of plant pathogenic fungi One aspect of the present invention is a method for inhibiting the growth of plant pathogenic fungi, which comprises a step of contacting mercaptopropionic acid with plant pathogenic fungi.

[0034] The mercaptopropionic acid used in the method of the present invention is as described above. The plant pathogen and the plant disease caused by the pathogen are also as described above.

[0035] The method of the present invention is characterized by contacting mercaptopropionic acid with plant pathogens. Contact of mercaptopropionic acid with plant pathogens is not particularly limited, and can be achieved, for example, by applying mercaptopropionic acid to soil or plants. As used herein, "soil" refers to soil in which plants can grow. The soil used may be, for example, culture soil, fertilizer, seedling soil, or seedling soil. Untreated mountain soil may also be used as is. The soil particle size is also not particularly limited, and any soil may be used as long as plants can grow therein. Although not particularly limited, the soil to which mercaptopropionic acid is applied is preferably soil near the plant (e.g., soil within 10 cm of the plant).

[0036] The plant to which mercaptopropionic acid is added may be a plant that is affected by the plant pathogenic fungus of the present invention, and is preferably an agricultural crop. The types and specific examples of the agricultural crop are as described above.

[0037] The state of the plant to which mercaptopropionic acid is applied is not particularly limited, and may be a seed or a seedling, or may be an already grown plant. The seed may be a rooted seed. When the plant is already grown, mercaptopropionic acid can be applied to any part of the plant, such as the roots, leaves, stems, branches, trunks, flowers, or fruits. When the disease caused by a plant pathogen is a soil-borne disease, the state of the plant to which mercaptopropionic acid is applied is preferably a seed or a seedling, and particularly preferably a seed. When the plant is in an early growth stage such as a seed or a seedling, the onset of soil-borne disease can be suppressed, and soil-borne disease in plants can be more effectively controlled. When the disease caused by a plant pathogen is an above-ground disease, the state of the plant to which mercaptopropionic acid is applied is preferably a seedling or an already grown plant, and particularly preferably a seedling. By treating the plants in the early growth stage, such as seedlings, it is possible to suppress the onset of above-ground disease damage, thereby enabling more effective control of above-ground plant diseases.

[0038] When mercaptopropionic acid is applied to soil or plants, the method and means for applying the same are not particularly limited as long as the effects of the present invention are obtained. For example, the application can be carried out by contacting soil or plants with mercaptopropionic acid itself or a composition containing mercaptopropionic acid. Mercaptopropionic acid and compositions containing it may be suspended or dissolved in water (or an aqueous solution), and the resulting solution may be contacted with soil or plants to apply the same.

[0039] The composition containing mercaptopropionic acid may be in the form of a liquid or a solid. When the composition is in the form of a liquid, mercaptopropionic acid can be applied to soil or plants by spraying, dripping, immersion, or other operations. In the case of immersion, a separate container may be prepared, and a perforated container containing soil or plants may be placed in the container containing the liquid. When the composition containing mercaptopropionic acid is in the form of a solid, or when solid mercaptopropionic acid itself is used, the composition may be applied by placing the solid on or in the soil, or by contacting the solid with the surface of the plant.

[0040] Furthermore, because mercaptopropionic acid is a volatile substance, it can be contacted with plant pathogens in a gaseous state (gaseous state). When mercaptopropionic acid is applied to soil or plants, it can volatilize from there and contact plant pathogens in a gaseous state. Unlike other non-volatile substances, mercaptopropionic acid, which has volatile properties, can be applied to plant pathogens even when it is located away from the plant pathogens. Furthermore, in a gaseous state, it can be contacted with plant pathogens over a wide area, and in some cases, it can be contacted with plant pathogens quickly. Furthermore, application in a gaseous state reduces the burden of spraying compared to water-soluble substances. These are extremely advantageous for suppressing the growth of plant pathogens. When mercaptopropionic acid is used in a gaseous state, it can be applied under conditions such as covering the soil with vinyl or the like. Furthermore, when mercaptopropionic acid is used in the form of a gaseous component, mercaptopropionic acid itself or a composition containing it can be used as a fumigant, although there are no particular limitations thereon.

[0041] The concentration (final concentration) of mercaptopropionic acid when used is not particularly limited, but is, for example, 1 μM or more, preferably 10 μM or more, more preferably 0.1 mM or more, 0.2 mM or more, or 0.5 mM or more, and even more preferably 1 mM or more, 2 mM or more, or 5 mM or more. Furthermore, although not particularly limited, the upper limit of the concentration (final concentration) of mercaptopropionic acid when used is, for example, 10 M or less, preferably 1 M or less, more preferably 100 mM or less, and even more preferably 10 mM or less. The concentration (final concentration) of mercaptopropionic acid when used is typically, for example, 1 μM to 10 M, preferably 10 μM to 1 M, more preferably 0.1 mM to 100 mM, and even more preferably 1 mM to 10 mM.

[0042] When mercaptopropionic acid is applied to soil or plants, the amount of mercaptopropionic acid to be applied is not particularly limited and can be appropriately determined depending on the application form, the type of target plant, etc. For example, when mercaptopropionic acid is applied to soil, 1 cm ３ The amount of the fertilizer can be 1 μM or more, preferably 10 μM or more, more preferably 0.1 mM or more, 0.2 mM or more, or 0.5 mM or more, and even more preferably 1 mM or more, 2 mM or more, or 5 mM or more per one application to the soil. ３ The amount of mercaptopropionic acid to be added to the soil at one time can be 10 M or less, preferably 1 M or less, more preferably 100 mM or less, and even more preferably 10 mM or less. When mercaptopropionic acid is added to the soil, the concentration (amount) of mercaptopropionic acid used is typically, for example, 1 μM to 10 M, preferably 10 μM to 1 M, more preferably 0.1 mM to 100 mM, and even more preferably 1 mM to 10 mM.

[0043] When mercaptopropionic acid is applied to plants, it can be applied in an amount of 1 μM or more, preferably 10 μM or more, more preferably 0.1 mM or more, 0.2 mM or more, or 0.5 mM or more, and even more preferably 1 mM or more, 2 mM or more, or 5 mM or more per plant. The upper limit is not particularly limited, but it can be 10 M or less, preferably 1 M or less, more preferably 100 mM or less, and even more preferably 10 mM or less per plant. When mercaptopropionic acid is applied to plants, the concentration (amount) of mercaptopropionic acid used is typically, for example, 1 μM to 10 M, preferably 10 μM to 1 M, more preferably 0.1 mM to 100 mM, and even more preferably 1 mM to 10 mM. The amount of mercaptopropionic acid applied can be adjusted by the concentration in a formulation containing it and the amount of the formulation applied.

[0044] When mercaptopropionic acid is applied to soil or plants, the timing of application may be any of before sowing the plants, at the time of sowing, and after sowing (including the seedling raising period, planting period, etc.), and is not particularly limited.

[0045] When the disease caused by the plant pathogen is a soil-borne disease, the timing of application of mercaptopropionic acid is preferably within 3 days before or after sowing of the plants. As used herein, "sowing" means planting a plant in soil as a starting point for growth, and includes, for example, sowing seeds in soil.

[0046] When mercaptopropionic acid is applied before sowing of plants, the specific timing is not particularly limited, but is, for example, within 7 days before sowing, within 6 days before sowing, within 5 days before sowing, within 4 days before sowing, within 3 days before sowing, within 2 days before sowing, within 1 day before sowing, within 12 hours before sowing, within 6 hours before sowing, within 3 hours before sowing, within 1 hour before sowing, within 30 minutes before sowing, within 10 minutes before sowing, within 5 minutes before sowing, within 1 minute before sowing, or within 30 seconds before sowing. Furthermore, when the mercaptopropionic acid is applied after sowing of plants, the application time may be within 7 days, 6 days, 5 days, or 4 days after sowing, or may be within 2 days, 1 day, 12 hours, 6 hours, 3 hours, 1 hour, 30 minutes, 10 minutes, 5 minutes, 1 minute, or 30 seconds after sowing. When the disease caused by a plant pathogen is a soil-borne disease, it is preferable that mercaptopropionic acid contacts the plant pathogen at an early stage of plant growth, and from this perspective, the shorter the period between the application time and the plant sowing time, the better. For example, it is preferable to apply the mercaptopropionic acid within 3 days before or after sowing, or within 1 day before or after sowing.

[0047] When the disease caused by a plant pathogen is an above-ground disease, the timing of application of mercaptopropionic acid may be either before or after sowing of the plant. When mercaptopropionic acid is applied before sowing of the plant, the specific timing is not particularly limited, and may be, for example, within 7 days, 6 days, 5 days, 4 days, 3 days, 2 days, 1 day, 12 hours, 6 hours, 3 hours, 1 hour, 30 minutes, 10 minutes, 5 minutes, 1 minute, or 30 seconds before sowing. When mercaptopropionic acid is applied to plants after sowing, it may be applied several weeks (e.g., 2 to 6 weeks) to several months (e.g., 2 to 6 months) after sowing, or it may be applied several years (e.g., 2 to 6 years) after sowing. In particular, when mercaptopropionic acid is also applied to plant leaves, it is preferable to apply it after confirming that the leaves have unfolded on the plant. The same applies to the flowers and fruits of the plant; it is preferable to apply mercaptopropionic acid after confirming the presence of flowers and fruits, respectively.

[0048] Mercaptopropionic acid may be continuously contacted with plant pathogens multiple times. Continuous contact with mercaptopropionic acid can effectively sustain growth inhibition of plant pathogens. Further contact with mercaptopropionic acid can be carried out one or more times, and may be two or more, three or more, four or more, or five or more times.

[0049] When the contact with mercaptopropionic acid is carried out continuously, the interval between further contacts with mercaptopropionic acid is not particularly limited, and may be, for example, 6 hours or more, 12 hours or more, 1 day or more, 2 days or more, 3 days or more, or 4 days or more, or may be 10 days or less, 7 days or less, 6 days or less, 5 days or less, 4 days or less, 3 days or less, 2 days or less, 1 day or less, or 12 hours or less. The further contact with mercaptopropionic acid can be carried out by further applying mercaptopropionic acid to the soil or plant, and the above-mentioned number of times and timing can be applied to the further application of mercaptopropionic acid to the soil or plant.

[0050] When mercaptopropionic acid is further applied to soil or plants, the form and means of applying mercaptopropionic acid are not particularly limited and can be the same as those described above. Furthermore, the amount of mercaptopropionic acid further applied is also not particularly limited and can be the same as those described above.

[0051] The method of the present invention is characterized by suppressing the growth of plant pathogens, and by using this method, it is possible to prevent plant diseases or protect plant growth. Therefore, another aspect of the present invention is a method for preventing plant diseases or a method for protecting plants (more specifically, a method for protecting plant growth). As described above, the plant disease is preferably a soil-borne disease or an above-ground disease. Both the method for preventing plant diseases and the method for protecting plants include a step of contacting mercaptopropionic acid with plant pathogens, and these methods may also include a step of carrying out the above-mentioned method (i.e., a method for suppressing the growth of plant pathogens).

[0052] The present invention will be described in detail below with reference to examples, but these examples are not intended to limit the technical scope of the present invention. Those skilled in the art can easily make modifications and changes to the present invention based on the description in this specification, and such modifications and changes are also included in the technical scope of the present invention.

[0053] Experimental Example 1 In order to examine the antibacterial effect of mercaptopropionic acid, an antibacterial test was carried out against Pythium, a plant pathogen.

[0054] 3-mercaptopropionic acid (Tokyo Chemical Industry Co., Ltd.) was used as mercaptopropionic acid (MPA). Furthermore, Pythium ultimum strain MAFF425494 was used for Pythium spp. 2,4-diacetylphloroglucinol (DAPG), a known antibacterial substance, was used as a control. The antibacterial test utilized a paired culture method. PDA solid medium (3.9 g of PDA (Sigma-Aldrich) and 0.3 g of Agar (Wako) per 100 mL) was prepared in a Petri dish (60 mm diameter). A Pythium colony (approximately 6 mm in diameter) was placed on one side of the dish at a distance of approximately 20 mm, and filter paper impregnated with a predetermined concentration of mercaptopropionic acid was placed on the other side. The dish was then cultured at 25°C for two days, and the growth of the Pythium spp. was examined.

[0055] The results showed that mercaptopropionic acid inhibited the growth of Pythium fungi in a concentration-dependent manner (Figs. 1 and 2).The results also suggested that the inhibitory effect of mercaptopropionic acid on plant pathogenic fungi was stronger than that of the known antifungal substance 2,4-diacetylphloroglucinol.

[0056] Experimental Example 2 Next, the effect of volatilization characteristics on the plant pathogen growth inhibitory activity of mercaptopropionic acid was investigated.

[0057] As in Experimental Example 1, 3-mercaptopropionic acid was used as the mercaptopropionic acid, and Pythium ultimum MAFF425494 strain was used as the Pythium bacterium. PDA solid medium was prepared in a Petri dish (60 mm diameter), and a Pythium bacterium colony (approximately 6 mm diameter) was placed near the center of the medium. Filter paper impregnated with a predetermined concentration of mercaptopropionic acid was then placed inside the Petri dish lid. The Petri dish with the filter paper placed on it was then placed on the lid, and the culture was incubated at 25°C for two days with the lid facing down, and the growth status of the Pythium bacterium was examined. The Petri dish was inverted with the lid facing down to prevent the filter paper from falling onto the culture medium.

[0058] The results showed that mercaptopropionic acid inhibited the growth of Pythium even in its volatile state, and that the effect was concentration-dependent (Figure 3). These results demonstrated that mercaptopropionic acid, even in its gaseous form, has the effect of inhibiting the growth of plant pathogens.

[0059] Experimental Example 3 The growth inhibitory effect of mercaptopropionic acid on other plant pathogenic fungi was also investigated. Fusarium oxysporum MAFF103054 strain was used as the Fusarium fungus, and Ralstonia solanacearum MAFF301522 strain was used as the Ralstonia bacterium.

[0060] Antibacterial tests were conducted on Fusarium fungi using the dual culture method in the same manner as in Experimental Example 1. The effect of volatility of mercaptopropionic acid was also investigated in the same manner as in Experimental Example 2. Fusarium fungi were cultured on PDA solid medium at 25°C for 5 days.

[0061] For Ralstonia bacteria, inhibition zone formation was examined using NA solid medium (4 g of blood agar base (Oxoid) and 0.5 g of yeast extract (Oxoid) per 100 mL). Ralstonia bacteria were cultured overnight in NYB liquid medium (5 g of nutrient broth (Oxoid) and 1 g of yeast extract (Oxoid) per 100 mL). Before the NA solid medium solidified, 10% (v / v) of the medium volume of Ralstonia bacteria was added to the medium and mixed. After the medium solidified, filter paper impregnated with a predetermined concentration of mercaptopropionic acid was placed near the center of the NA solid medium, and the medium was cultured at 25°C for 3 days.

[0062] As a result, the growth inhibitory effect on Fusarium spp. was confirmed, similar to that on Pythium spp. (Figure 4). Furthermore, the effect was concentration-dependent, and growth inhibition was also demonstrated in volatile mercaptopropionic acid. For Ralstonia spp., inhibition zones were formed after incubation, confirming growth inhibition (Figure 5). These results suggest that mercaptopropionic acid has a broad antibacterial spectrum.

[0063] Experimental Example 4 The effective concentration of mercaptopropionic acid was investigated. The target plant pathogenic fungi were Pythium and Ralstonia, with Pythium ultimum strain MAFF425494 used as the Pythium fungus and Ralstonia solanacearum strain MAFF301522 used as the Ralstonia fungus.

[0064] For Pythium spp., modified WSH medium (MgSO per 100 mL) was placed in a 24-well plate. ４ ・7H ２ O 0.1g, KH ２ P.O. ４ 0.1g NaNO ３ 1 mL of a Pythium ultimum spore suspension (adjusted to OD600 = 0.48) was added to each well, and the mixture was cultured at 28°C and 80 rpm for 3 days.

[0065] For Ralstonia bacteria, 1 mL of modified WSH medium was dispensed into a 24-well plate in the same manner as above, and 2 μL or 5 μL of Ralstonia solanacearum culture solution (overnight culture, no OD adjustment) was added, followed by cultivation at 28°C and 100 rpm for 5 days.

[0066] As a result, it was shown that mercaptopropionic acid was effective in inhibiting the growth of Pythium and Ralstonia bacteria at concentrations of 0.1 mM or more or 0.2 mM or more (FIGS. 6 and 7).

[0067] Experimental Example 5 A disease control test was carried out using a plant. Cucumber was used as the plant, and the disease control effect of mercaptopropionic acid on an infectious disease caused by a soil pathogen, Pythium ultimum (Pythium ultimum MAFF425494 strain), was examined.

[0068] To prepare soil infected with Pythium, water was first added to vermiculite and allowed to soak. Then, millet (foxtail millet) infected with Pythium was added to the vermiculite and thoroughly mixed. 10 g of millet infected with Pythium was added to 1 L of vermiculite. A portion of the vermiculite was set aside as a control without the addition of millet infected with Pythium.

[0069] Mercaptopropionic acid solutions were prepared using 3-mercaptopropionic acid (Tokyo Chemical Industry Co., Ltd.) to final concentrations of 2 mM and 5 mM. Various concentrations of mercaptopropionic acid solutions were then applied to the vermiculite prepared as described above. For comparison, tests were also conducted in which water alone or ethanol at final concentrations of 2 mM or 5 mM was applied in place of mercaptopropionic acid.

[0070] The vermiculite to which the mercaptopropionic acid solution or the comparative samples had been applied was evenly divided into seedling trays (5 cm square, 5 cm deep per section) at 50 mL each. Three cucumber seeds were then sown in each seedling tray. The mercaptopropionic acid solution and the comparative samples were applied within one day before sowing the cucumber seeds. The amount of mercaptopropionic acid solution and the comparative samples applied was 15 mL per section of the seedling tray.

[0071] The seedling trays were placed in a plant incubator set at 25° C. The light period was set to 16 hours and the dark period to 8 hours, and the cultivation period in the incubator was 2 weeks. The number of surviving cucumbers 2 weeks after sowing was counted and evaluated.

[0072] The results are shown in Figure 8. In soil infected with Pythium, the highest number of surviving cucumbers was observed when 5 mM mercaptopropionic acid was applied, followed by 2 mM mercaptopropionic acid. On the other hand, when water alone or ethanol (2 mM and 5 mM) was applied to the Pythium-infected soil, the number of surviving cucumbers decreased, confirming the influence of Pythium. These results demonstrate that mercaptopropionic acid inhibits the growth of plant pathogens such as Pythium and is effective in protecting plants from disease. In this experimental example, when 5 mM mercaptopropionic acid was applied to soil not infected with Pythium, the number of surviving cucumbers was the same as when only water was applied to soil not infected with Pythium. These results demonstrate that mercaptopropionic acid does not affect the growth of cucumber.

[0073] Experimental Example 6 Tomatoes were used as plants, and the disease control effect of mercaptopropionic acid was investigated for infectious diseases caused by bacterial wilt (a bacterium of the genus Ralstonia), a soil pathogen.

[0074] Mercaptopropionic acid solutions were prepared using 3-mercaptopropionic acid (Tokyo Chemical Industry Co., Ltd.) as the mercaptopropionic acid, with final concentrations of 2 mM and 5 mM. The mercaptopropionic acid solutions of various concentrations were then irrigated around the base of tomato plants that had been previously grown in vermiculite (1000-fold diluted Hyponex was used as a nutrient). The roots of the tomato plants were then cut with scissors, and 2 x 10 ８ 10 mL of bacterial wilt bacteria (Ralstonia solanacearum strain 8107S) adjusted to cfu / mL was irrigated and cultivated at 30°C.

[0075] The condition of tomato leaves was observed 2 days (2 dpi) and 4 days (4 dpi) after irrigation with R. solanacearum. Specifically, the percentage of withered leaves was examined for each tomato plant, and the number of plants with withered leaves was counted.

[0076] The results are shown in Figures 10 and 11. Application of a predetermined concentration of mercaptopropionic acid reduced the incidence of bacterial wilt in tomatoes. These results demonstrate that mercaptopropionic acid has the effect of controlling underground plant diseases (soil diseases) caused by the bacterial wilt fungus.

[0077] Experimental Example 7 Cucumber was used as the plant, and the disease control effect of mercaptopropionic acid on an infectious disease of above-ground parts caused by anthracnose fungus was investigated.

[0078] Cucumbers were grown using vermiculite under conditions of 18 hours of light and 6 hours of darkness while being fed with 1000-fold diluted Hyponex as nutrients. Approximately 1 × 10 ５ The anthracnose fungus (Colletotrichum orbiculare (MAFF240422)) was inoculated by spraying at a concentration of spores / mL. Approximately 30 minutes after inoculation with the anthracnose fungus, a 5 mM 3-mercaptopropionic acid solution or distilled water was sprayed on the leaves. The treated cucumbers were placed in a sealed container to maintain humidity for approximately four days, after which the container was removed and grown for three days.

[0079] The condition of the leaves of the grown cucumbers (7 days after inoculation with anthracnose fungus (7 dpi)) was observed. In addition, the same experiment as above was performed, except that the treated cucumbers were placed in a sealed container for about 4 days, and then the container lid was removed and the cucumbers were grown for 7 days (11 days after inoculation with anthracnose fungus (11 dpi)). The condition of the leaves was also observed.

[0080] As a result, for cucumbers treated with mercaptopropionic acid at 7 dpi, the number of diseased plants was smaller and the severity of disease symptoms was lower than for the distilled water-treated group (Fig. 12). Similar results were obtained for cucumbers treated with distilled water at 11 dpi, with the severity of disease symptoms becoming even worse in the distilled water-treated group, and the difference from the mercaptopropionic acid-treated group becoming larger (Fig. 13).

[0081] The technology provided by the present invention is particularly useful in the agricultural field in that it can suppress the growth of plant pathogens and protect plants from disease. The compositions and methods provided by the present invention can be used in the agricultural chemical field.

Claims

1. A composition for inhibiting the growth of plant pathogens, comprising mercaptopropionic acid.

2. The composition according to claim 1, wherein the plant pathogen is a plant pathogen that causes a soil-borne disease or an above-ground disease.

3. A method for inhibiting the growth of plant pathogens, comprising the step of contacting mercaptopropionic acid with plant pathogens.

4. The method according to claim 3, wherein the plant pathogen is a plant pathogen that causes a soil-borne disease or an above-ground disease.

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