Plant activator

Abstract

To provide a plant activator which shows little soil pollution and toxicity, and has an excellent resistance induction effect.SOLUTION: Provided is a plant activator comprising, as an active ingredient, an oxo fatty acid derivative having a structural formula: HOOC-(R1)-C=C-C(=O)-R2(I) (in the formula, R1 is a linear or branched C6-12 alkyl group which may contain one or more double bonds and R2 is a C2-8 alkyl group which may contain one or more branches and / or double bonds), a salt thereof, or an ester thereof.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a plant activator. [Background technology]

[0002] Since ancient times, measures such as optimizing temperature and sunlight conditions and applying fertilizer have been taken to promote plant growth. However, these measures have limitations. For example, not only can the amount of fertilizer used be increased, but it is also difficult to expect growth promotion beyond a certain level. In addition, applying too much fertilizer can actually hinder plant growth and even lead to soil contamination.

[0003] Therefore, in addition to the above-mentioned measures, methods have been reported for activating plants using plant activators that have plant growth regulating effects such as growth promotion, dormancy suppression, and stress suppression. For example, Patent Document 1 describes a flower bud formation inducer that contains an α-ketol unsaturated fatty acid as an active ingredient. Patent Document 2 describes a plant activator that contains a ketol fatty acid having 4 to 24 carbon atoms as an active ingredient. Patent Document 3 describes a plant growth regulator that contains an α-ketol fatty acid derivative as an active ingredient.

[0004] While plant pest control relies heavily on synthetic pesticides, reducing pesticide use is desirable due to soil contamination and human health risks. Excessive pesticide application also poses a problem, leading to the emergence of pesticide-resistant bacteria. Therefore, the use of plant resistance inducers that induce disease resistance without direct antibacterial activity has been proposed. Examples of commercially available plant resistance inducers include propenazole, isotianil, acibenzolar-S-methyl (ASM), and 3'-chloro-4,4'-dimethyl-1,2,3-thiadiazole-5-carboxanilide (thiadinil). These plant resistance inducers are salicylic acid analogs that activate the salicylic acid pathway in plants, which induces systemic acquired resistance via salicylic acid analogs elicited by pathogenic bacteria and viruses. Validamycin is a pesticide that inhibits the activity of trehalose-degrading enzymes, thereby depleting the pathogen's energy source and suppressing bacterial growth. It has also been reported to induce systemic acquired resistance in bacterial wilt pathogens. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 9-295908 [Patent Document 2] Japanese Patent Application Laid-Open No. 2001-131006 [Patent Document 3] International Publication No. 2011 / 034027 Summary of the Invention [Problem to be solved by the invention]

[0006] The effects of the plant activators using ketol fatty acids described in Patent Documents 1 to 3 are insufficient. Furthermore, conventional plant resistance inducers are chemically synthesized and have the problem of being extremely toxic. Furthermore, while validamycin is considered effective against bacterial wilt disease in solanaceous plants, it cannot be used on tomatoes because it causes phytotoxicity. Other synthetic plant resistance inducers also tend to be prone to phytotoxicity, and furthermore, they are insufficient in expressing resistance genes or conferring resistance. There is a demand for plant activators that have a low environmental impact and excellent activating effects, including inducing and expressing resistance.

[0007] It is known that fatty acid oxidation products, including lipid peroxides, exhibit antibacterial properties. Furthermore, 13-oxo-9,11-octadecadienoic acid, an oxo fatty acid derived from tomatoes, has potent agonist activity, activating the transcription factor PPARα (peroxisome proliferator-activated receptor α subtype), which controls the expression of various genes related to lipid metabolism. It has also been reported that it may improve lipid metabolism disorders such as hypertriglyceridemia and fatty liver. However, it is not known that oxo fatty acids have the effect of plant activators.

[0008] An object of the present invention is to provide a plant activator that is less toxic and less likely to pollute soil, and has an excellent resistance induction effect. [Means for solving the problem]

[0009] The present invention relates to a compound of the formula: HOOC-(R 1 )-C=CC(=O)-R 2 (I) (In the formula, R 1 : a linear or branched alkyl group having 6 to 12 carbon atoms, which may contain one or more double bonds; R 2 : an alkyl group having 2 to 8 carbon atoms, which may contain one or more branches and / or double bonds) The present invention relates to a plant activator characterized by containing, as an active ingredient, an oxo fatty acid derivative having the structural formula:

[0010] The oxo fatty acid derivative is R 1 The alkyl group has 8 to 10 carbon atoms, and R 2 The plant activator is preferably an oxo fatty acid derivative in which the alkyl group has 4 to 6 carbon atoms.

[0011] The oxo fatty acid derivative is R 1 Preferred are plant enhancers which are oxo fatty acid derivatives containing a double bond which forms a conjugated double bond with the double bond between the α and β carbons of the carbonyl group in formula (I).

[0012] The oxo fatty acid derivative is R 1 is an alkyl group having 9 carbon atoms, and R 2 However, a plant activator that is an oxo fatty acid derivative having an alkyl group with 5 carbon atoms is preferred.

[0013] The plant activator is preferably one in which the oxo fatty acid derivative is (9Z,11E)-13-oxo-9,11-octadecadienoic acid or a salt thereof.

[0014] The plant activator is preferably one in which the oxo fatty acid derivative is (9Z,11E)-13-oxo-9,11-octadecadienoic acid.

[0015] The plant activator is preferably a plant activator further containing 12-oxo-phytodienoic acid or a salt thereof.

[0016] The plant activator is preferably a plant activator further comprising a surfactant and / or a diluent or carrier.

[0017] The plant activator preferably contains the oxo fatty acid derivative or its salt or ester at a concentration of 0.012 to 0.12 g / l (liter).

[0018] The plant activator preferably contains 12-oxo-phytodienoic acid or a salt thereof at a concentration of 0.012 to 0.12 g / l.

[0019] The plant activator is preferably a plant activator used as a spray or dipping agent to be brought into contact with the stems, leaves or roots of plants, or as a soil drench agent.

[0020] The plant activator is preferably a plant activator used for plants of the Brassicaceae family. [Effects of the Invention]

[0021] The plant activator of the present invention is easily decomposed in the environment, so that it causes little soil contamination and toxicity, and has an excellent resistance induction effect. [Brief explanation of the drawings]

[0022] [Figure 1] 1 is a graph showing the expression level of resistance genes. [Figure 2] 1 is a graph showing the expression level of resistance genes. DETAILED DESCRIPTION OF THE INVENTION

[0023] Plant activators The plant activator of the present invention is an oxo fatty acid derivative having the following formula: HOOC-(R 1 )-C=CC(=O)-R 2 (I) (In the formula, R 1 : a linear or branched alkyl group having 6 to 12 carbon atoms, which may contain one or more double bonds; R 2 : an alkyl group having 2 to 8 carbon atoms, which may contain one or more branches and / or double bonds) The present invention is characterized by comprising, as an active ingredient, an oxo fatty acid derivative having the structural formula: or a salt or ester thereof. The present invention also relates to a plant activator comprising, as an active ingredient, the compound of formula (I) or its salt or ester, including all geometric isomers and stereoisomers.

[0024] In the present invention, "plant activation" refers to regulating plant growth activity in some way to activate or maintain it. This concept encompasses plant growth regulating actions such as growth promotion (a concept that includes the promotion of stem and leaf expansion, tuber and root growth, etc.), dormancy suppression, induction or conferring of plant stress resistance, and anti-aging. For example, resistance can be induced in plants by contacting a portion of a plant's stem, leaf, or root with the plant activator of the present invention. Since inoculation with the plant activator of the present invention confirmed an increase in the expression levels of the resistance genes PR1 and PR2 in plants, it is believed that the plant activator of the present invention induces systemic resistance via the salicylic acid pathway. Use of the plant activator of the present invention can promote the development of organs and the production of substances related to pest and disease resistance in plants. The plant activator of the present invention has an extremely high resistance-inducing effect, resulting in excellent plant disease suppression effects.

[0025] Oxo fatty acids are rare fatty acids known to be produced as intermediates in the metabolism of unsaturated fatty acids. 13-oxo-9,11-octadecadienoic acid, used as an example of an oxo fatty acid derivative in the present invention, is one of the metabolites obtained by the oxidative metabolism of linoleic acid. Linoleic acid is converted to a lipid peroxide (hydroperoxyoctadecadienoic acid (HPODE)) either enzymatically by lipoxygenase, a linoleic acid metabolic enzyme, or non-enzymatically by oxidation with free radicals produced by oxidative stress. This lipid peroxide HPODE is then converted to hydroxyoctadecadienoic acid (HODE) by peroxidase or other enzymes. Oxooctadecadienoic acid is produced from hydroxyoctadecadienoic acid (HODE) by hydroxyfatty acid dehydrogenase or other enzymes. Oxooctadecadienoic acid can also be produced by converting the lipid peroxide HPODE to epoxyoctadecadienoic acid through the action of allene oxide synthase and then fatty acid hydroperoxide lyase.

[0026] Linoleic acid, on the other hand, is converted to linolenic acid by fatty acid desaturase. Linolenic acid is converted to the lipid peroxide (hydroperoxyoctadecatrienoic acid (HPOTE)) by lipoxygenase. This lipid peroxide, HPOTE, is then converted to the allene oxide, epoxyoctadecatrienoic acid, by the action of allene oxide synthase and then allene oxide cyclase, via epoxyoctadecatrienoic acid, to 12 / 10-oxo-phytodienoic acid (12 / 10-OPDA), a precursor to jasmonic acid. Lipoxygenase also produces ketol fatty acids from epoxyoctadecatrienoic acid. The lipid peroxide, HPOTE, is also converted to the conjugated lipid oxide, hydroxyoctadecatrienoic acid (HOTE), by reductase.

[0027] As will be described later, the high resistance induction effect of the plant activator of the present invention cannot be obtained when the above-mentioned lipid peroxides (HPODE, HPOTE) or conjugated lipid oxides (HOTE) are used instead of oxo fatty acids. In particular, since the lipid peroxide (13-HPODE), a precursor of 13-oxo-9,11-octadecadienoic acid, does not exhibit the resistance induction effect of the plant activator of the present invention, it is believed that the excellent resistance induction effect of the plant activator of the present invention is specific to oxo fatty acids.

[0028] Furthermore, the jasmonic acid precursor 12 / 10-OPDA, which has been known to induce the expression of resistance genes in the jasmonic acid pathway, the conjugated oxidized lipid HOTE, which has been reported to induce the expression of resistance genes in the salicylic acid pathway involved in systemic resistance, and ketol fatty acids are all fatty acid analogs synthesized from linolenic acid, which is produced from linoleic acid, as described above. In contrast, the 13-oxo-9,11-octadecadienoic acid used in the present invention is produced directly from linoleic acid without passing through linolenic acid. In other words, the resistance-inducing effect of 13-oxo-9,11-octadecadienoic acid in the present invention was first obtained as a result of targeting a novel metabolic pathway of linoleic acid to induce more effective resistance.

[0029] The 13-oxo-9,11-octadecadienoic acid used in the present invention is a naturally occurring metabolite obtained by the metabolism of linoleic acid. In other words, the plant activator of the present invention, which uses a naturally occurring metabolite, is thought to be in line with the metabolic pathway of plants and to be easily functional. Furthermore, it is thought to be easily decomposed in the environment after application to plants, so the possibility of soil contamination and toxicity are low.

[0030] The plant activator of the present invention induces systemic resistance in plants via the salicylic acid pathway and suppresses plant diseases. The plant activator of the present invention may also be used in combination with other plant resistance inducers. For example, the plant activator of the present invention can be applied to plants in the presence of the jasmonic acid precursor 12 / 10-OPDA, which induces the expression of resistance genes in the jasmonic acid pathway. The salicylic acid pathway and the jasmonic acid pathway are activated in a complementary manner, thereby inducing even greater plant resistance. Other plant resistance inducers, such as jasmonic acid precursors, can be used in combination with the oxo fatty acid derivatives or their salts or esters of the present invention, for example, at concentrations similar to those of the oxo fatty acid derivatives or their salts or esters of the present invention.

[0031] The plant activator of the present invention may contain, as necessary, a compatible surfactant and / or diluent or carrier suitable for use in the plant activator. For example, the diluent may improve the dispersibility of, for example, 13-oxo-9,11-octadecadienoic acid or its salt or ester. Furthermore, to improve the solubility or dispersibility of the oxo fatty acid derivative used in the present invention in the diluent, surfactants such as dispersing aids and wetting agents may be contained. These additional components are not particularly limited as long as they are agriculturally acceptable. Furthermore, components commonly used in pesticide formulations, etc., other than surfactants, diluents, and carriers, may also be contained.

[0032] In the present invention, the oxo fatty acid derivative, or its salt or ester, can be used at a concentration of 0.12 g / L or less. The preferred concentration of the oxo fatty acid derivative, or its salt or ester, depends on the plant species and its condition to which it is applied, but concentrations exceeding 0.12 g / L may cause phytotoxicity to the plant. There is no particular lower limit for the concentration of the oxo fatty acid derivative, or its salt or ester, but 0.012 g / L or higher is preferred. In the present invention, the concentration of the oxo fatty acid derivative, or its salt or ester, is preferably 0.012 to 0.12 g / L.

[0033] The plant activator of the present invention may contain an oxo fatty acid derivative or its salt or ester, and there are no particular limitations on its origin. The oxo fatty acid derivative, such as 13-oxo-9,11-octadecadienoic acid, or its salt or ester of the present invention may be obtained, for example, by chemical synthesis, or may be produced using a microorganism or by reacting a microbial enzyme with a substrate such as a fatty acid. In particular, 13-oxo-9,11-octadecadienoic acid is highly lipid-soluble, so in practical terms, adding a salt to alkalize it to make it water-soluble for ease of handling. Ammonium salts and metal salts are commonly used as salts, and metal salts that generate monovalent metal ions are preferred, with lithium, sodium, and potassium salts being particularly preferred. The plant activator of the present invention may contain the oxo fatty acid derivative at the desired concentration. For example, when 13-oxo-9,11-octadecadienoic acid produced using a microorganism is used as the oxo fatty acid derivative, a mixture containing 13-oxo-9,11-octadecadienoic acid may be used as the plant activator. When a biosurfactant secreted by the microorganism is contained in the mixture, the dispersibility of the plant activator of the present invention may be improved without the addition of the aforementioned additive components. When the oxo fatty acid derivative itself is insoluble, it may be possible to emulsify it with a biosurfactant and disperse it in water.

[0034] The plant activator of the present invention can be applied to plants by any method. For example, it can be used as a spray or dipping agent that is brought into contact with the stems, leaves, or roots of plants, or as a soil drench agent. In plants to which it is applied, the plant activator of the present invention induces systemic resistance in the plant via the salicylic acid pathway, thereby suppressing plant disease. Furthermore, because 13-oxo-9,11-octadecadienoic acid, for example, is a naturally occurring fatty acid oxide, the plant activator of the present invention is also excellent in that it has a low environmental impact and causes almost no phytotoxicity to the plants to which it is applied.

[0035] The plants to which the plant activator of the present invention can be applied are not particularly limited, and can be used effectively for plants in general, including, for example, plants of the Brassicaceae family. [Example]

[0036] The present invention will be described based on examples, but the present invention is not limited to only the examples.

[0037] Example 1 Evaluation of resistance gene expression In Example 1, a 0.15% aqueous solution of dipotassium hydrogen carbonate containing 0.012% 13-oxo-9,11-octadecadienoic acid was prepared. Note that (9Z,11E)-13-oxo-9,11-octadecadienoic acid (13-oxoODA, manufactured by Cayman Chemical Company) was used as the 13-oxo-9,11-octadecadienoic acid. As comparative examples, 0.012% of fatty acid analogues, 13-HPODE ((9Z,11E)-13-hydroperoxy-9,11-octadecadienoic acid, manufactured by Cayman Chemical Co.), 9-HPODE ((10Z,12E)-9-hydroperoxy-10,12-octadecadienoic acid, manufactured by Cayman Chemical Co.), 9-HPOTE ((10E,12Z,15Z)-9-hydroperoxy-10,12,15-octadecatrienoic acid, manufactured by Cayman Chemical Co.), and 9-HOTE ((10E,12Z,15Z)-9-hydroxy-10,12,15-octadecatrienoic acid, manufactured by Cayman Chemical Co.), were used. A 0.15% aqueous solution of dipotassium bicarbonate containing 13-HPOTE ((9Z,11E,15Z)-13-hydroperoxy-9,11,15-octadecatrienoic acid, Cayman Chemical Co.), 13-HOTE ((9Z,11E,15Z)-13-hydroxy-9,11,15-octadecatrienoic acid, Cayman Chemical Co.), 12-OPDA (12-oxo-phytodienoic acid, Cayman Chemical Co.), and 0.012% α-ketol fatty acids was prepared. The α-ketol fatty acid aqueous solution was synthesized as follows.

[0038] Ten mg of soybean-derived lipoxidase (Sigma-Aldrich) was added to a linoleic acid suspension consisting of 1 g of linoleic acid, 0.15 g of potassium dihydrogen phosphate, and 100 ml of distilled water, and the mixture was stirred overnight to produce lipid peroxide 1. The production of lipid peroxide 1 was confirmed by comparison with a standard substance by TLC (developing solvent: chloroform:ethanol = 20:1, sulfuric acid coloring) and by an increase in OD at 234 nm. NMR also confirmed that the major component of lipid peroxide 1 was 13-HPODE ((9Z,11E)-13-(hydroperoxy)-9,11-octadecadienoic acid).

[0039] 0.1 mg of allene oxide synthase (Sigma-Aldrich) was added to the obtained peroxide 1, and the mixture was stirred for 24 hours to obtain an α-ketol fatty acid having 18 carbon atoms. The enzymatic reaction was then terminated by adding dilute hydrochloric acid under ice cooling to adjust the pH of the reaction solution to 3.0. The pH was then adjusted to 6.5 to obtain an aqueous α-ketol fatty acid solution.

[0040] Example 2 Evaluation of resistance gene expression In Example 2, a 0.15% aqueous solution of dipotassium hydrogen phosphate containing 0.012% 13-oxo-9,11-octadecadienoic acid was prepared. Note that (9Z,11E)-13-oxo-9,11-octadecadienoic acid (13-oxoODA, manufactured by Cayman Chemical Company) was used as the 13-oxo-9,11-octadecadienoic acid. As comparative examples, 0.012% of fatty acid analogues, 13-HPODE ((9Z,11E)-13-hydroperoxy-9,11-octadecadienoic acid, manufactured by Cayman Chemical Co.), 9-HPODE ((10Z,12E)-9-hydroperoxy-10,12-octadecadienoic acid, manufactured by Cayman Chemical Co.), 9-HPOTE ((10E,12Z,15Z)-9-hydroperoxy-10,12,15-octadecatrienoic acid, manufactured by Cayman Chemical Co.), and 9-HOTE ((10E,12Z,15Z)-9-hydroxy-10,12,15-octadecatrienoic acid, manufactured by Cayman Chemical Co.), were used. 0.15% aqueous solutions of dipotassium hydrogen phosphate containing 13-HPOTE ((9Z,11E,15Z)-13-hydroperoxy-9,11,15-octadecatrienoic acid, manufactured by Cayman Chemical Co.), 13-HOTE ((9Z,11E,15Z)-13-hydroxy-9,11,15-octadecatrienoic acid, manufactured by Cayman Chemical Co.), 12-OPDA (12-oxo-phytodienoic acid, manufactured by Cayman Chemical Co.), and 0.012% α-ketol fatty acids were prepared. The α-ketol fatty acid aqueous solutions were synthesized by the same synthesis method as in Example 1.

[0041] The aqueous solutions obtained in Examples 1 and 2 were irrigated only onto the roots (underground parts) of Arabidopsis plants grown in soil. 24 hours after treatment, RNA was extracted from each Arabidopsis plant treated with each aqueous solution and from untreated control Arabidopsis plants, and cDNA was prepared from the RNA. The expression levels of the resistance genes PR1, PR2, and PDF1.2 were examined by real-time PCR. The gene expression levels were normalized to those of housekeeping genes. The results are shown in Figure 1 (Example 1) and Figure 2 (Example 2).

[0042] Figures 1 and 2 show that 13-oxoODA significantly increased the expression of the genes PR1 and PR2 (salicylic acid metabolism system), which are responsible for resistance to pathogens, compared to other substances. On the other hand, 12-OPDA significantly increased the expression of the gene PDF1.2 (jasmonic acid metabolism system), which is responsible for resistance to pests, compared to other substances.

[0043] Example 3: Effect of combined use on resistance gene expression A 0.15% aqueous solution of dipotassium bicarbonate containing 0.012% each of (9Z,11E)-13-oxo-9,11-octadecadienoic acid (13-oxoODA, manufactured by Cayman Chemical Co.) and the fatty acid analogue 12-OPDA (12-oxo-phytodienoic acid, manufactured by Cayman Chemical Co.) was prepared.

[0044] Example 4 Combined Effect on Resistance Gene Expression A 0.15% aqueous solution of dipotassium hydrogen phosphate containing 0.012% each of (9Z,11E)-13-oxo-9,11-octadecadienoic acid (13-oxoODA, manufactured by Cayman Chemical Co.) and the fatty acid analogue 12-OPDA (12-oxo-phytodienoic acid, manufactured by Cayman Chemical Co.) was prepared.

[0045] Arabidopsis thaliana was treated with the prepared aqueous solution in the same manner as in Examples 1 and 2, RNA was extracted, and cDNA was prepared from the RNA. The expression levels of the resistance genes PR1, PR2, and PDF1.2 were examined in the same manner as in Examples 1 and 2. The results are shown in Figure 1 (Example 3) and Figure 2 (Example 4).

[0046] A mixture of 13-oxoODA and 12-OPDA was able to simultaneously express PR1 and PDF1.2. It is speculated that a mixture of these two compounds can activate the salicylic acid metabolic pathway and the jasmonic acid metabolic pathway in a complementary manner. Furthermore, potassium salts were added to the aqueous solutions evaluated in Examples 1 to 4 to increase the water solubility of 13-oxoODA and 12-OPDA, indicating that some of the compounds existed as these potassium salts.

[0047] From the above results, it can be seen that the plant activator of the present invention is a plant activator with low soil contamination and toxicity and excellent resistance induction effect.

Claims

1. The following formula: HOOC-(R 1 )-C=C-C(=O)-R 2 (I) (In the formula, R 1 : a linear or branched alkyl group having 6 to 12 carbon atoms, which may contain one or more double bonds; R 2 : an alkyl group having 2 to 8 carbon atoms, which may contain one or more branches and / or double bonds) or a salt or ester thereof, and metal salts A plant activator comprising:

2. The plant activator according to claim 1, wherein the oxo fatty acid derivative: R 1 the alkyl group has 8 to 10 carbon atoms, R 2 The alkyl group has 4 to 6 carbon atoms.

3. 3. The plant activator according to claim 1 or 2, wherein the oxo fatty acid derivative: R 1 contains a double bond that forms a conjugated double bond with the double bond between the α and β carbons of the carbonyl group in formula (I).

4. The plant activator according to claim 3, wherein the oxo fatty acid derivative: R 1 is an alkyl group having 9 carbon atoms, R 2 is an alkyl group having 5 carbon atoms.

5. 5. The plant activator according to claim 4, wherein the oxo fatty acid derivative is (9Z,11E)-13-oxo-9,11-octadecadienoic acid or a salt thereof.

6. 6. The plant activator according to claim 5, wherein the oxo fatty acid derivative is (9Z,11E)-13-oxo-9,11-octadecadienoic acid.

7. 7. The plant activator according to claim 1, wherein the oxo fatty acid derivative or its salt or ester is contained in an aqueous solution of the metal salt.

8. 8. The plant activator according to claim 1, wherein the metal salt generates a monovalent metal ion.

9. 9. The plant activator according to claim 8, wherein the metal salt is a potassium salt.

10. The plant activator according to any one of claims 1 to 9, further comprising a surfactant and / or a diluent or carrier.

11. The plant activator according to any one of claims 1 to 10, which is used as a spray or dipping agent to be brought into contact with the stems, leaves or roots of plants, or as a soil drench agent.

12. The plant activator according to any one of claims 1 to 11, which is used for plants of the Brassicaceae family.

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