Germination inducer for root parasitic plant

Abstract

Provided is a germination inducer for a root parasitic plant, characterized by containing strigolactones and jasmonic acids as active ingredients to enable germination of a root parasitic plant with a small amount of strigoalactones.

Description

Germination inducer for root parasitic plants

[0001] TECHNICAL FIELD The present invention relates to a germination inducer for root parasitic plants and a method for inducing germination of root parasitic plants. TECHNICAL FIELD The germination inducer for root parasitic plants and the method for inducing germination of root parasitic plants of the present invention are useful for controlling root parasitic plants.

[0002] Root parasitic plants are a general term for plants that parasitize the roots of their host plants and then connect their vascular tissue to the host's vascular tissue, thereby robbing the host of water and nutrients. In regions such as Africa, parasitism of major grains such as corn and sorghum is common, causing significant agricultural damage. Striga, a representative root parasitic plant, is known as "witchweed" and poses a threat to crop production in Africa. While there have been few reports of agricultural damage in Japan, an invasive root parasitic plant called Orobanche grows ubiquitously. Striga possesses chloroplasts and is capable of photosynthesis, whereas root parasitic plants in the Orobanche genus, including Orobanche, lack chloroplasts and are completely dependent on their hosts for water and nutrients. Furthermore, these parasitic plants ultimately disperse as many as 100,000 tiny seeds, approximately 0.3 mm in diameter, onto agricultural land, making it impossible to remove the seeds from contaminated fields.

[0003] A key feature of the life cycle of root parasitic plants is their ability to germinate in response to molecules called "strigolactones" secreted by the roots of host plants. This can be seen as an ingenious survival strategy acquired by root parasitic plants, which cannot survive without parasitism. Taking advantage of this mechanism, a "suicide germination method" has been devised, in which strigolactones are sprayed on farmland in the absence of a host, forcing the plant to germinate and eventually die (Non-Patent Document 1). This holds promise for chemical seed control. However, one of the key requirements for this method to be put to practical use is the preparation of a large amount of strigolactone sufficient for spraying on farmland. While its effectiveness has been demonstrated, this remains a challenge, and the suicide germination method has not yet been put to practical use.

[0004] Uraguchi et al., Science. 2018 Dec 14;362(6420):1301-1305.

[0005] As mentioned above, it is difficult to supply large amounts of strigolactone, which is a major obstacle to the practical application of suicide germination induction methods. The present invention was made against this background, and aims to provide a means for inducing germination of root parasitic plants using small amounts of strigolactone.

[0006] As a result of extensive research to solve the above problems, the present inventors have discovered that the germination-inducing effect is synergistically improved when strigolactone is used in combination with jasmonic acids, which have a germination-inducing effect similar to that of strigolactone, and have completed the present invention based on this finding. Specifically, the present invention provides the following [1] to

[12] .

[0007] [1] A compound represented by the following formula (Ia), formula (Ib), formula (Ic), or formula (Id): [wherein R1 represents a hydrogen atom or a methyl group, R2 represents a hydrogen atom or a methyl group, R3 represents a hydrogen atom, a hydroxy group, or an acetoxy group, R4 and R5 each independently represent a hydrogen atom, a methyl group, or a hydroxymethyl group, or R4 and R5 together represent a methylene group, R6 represents a hydrogen atom or a methyl group, R7 and R8 each independently represent a hydrogen atom, a hydroxy group, or an acetoxy group, or R7 and R8 together represent an oxygen atom, R9 represents a hydrogen atom, a hydroxy group, or an acetoxy group, R 10 represents a methyl group or a hydroxymethyl group, and R 11 represents a hydrogen atom or a hydroxy group, and R 12 represents a methyl group or a hydroxymethyl group, and the dotted triangle with an oxygen atom in formula (Ib) indicates the presence of either a double bond or an epoxide. [In the formula, R 13 -CH2-COOH, -CH2-COOR 15 (However, R 15represents an amino acid residue or an alkyl group having 1 to 4 carbon atoms, or -(CH2)7-COOH, and R 14 represents a hydrogen atom or a hydroxy group, and the double line portion consisting of a solid line and a dotted line represents a single bond or a double bond.

[0008] [2] The compound represented by the following formula (Ia), formula (Ib), formula (Ic), or formula (Id) is GR24, fabacol, fabasyl acetate, 4-deoxyorobanchol, phelipanchol, orobancil acetate, orobanchol, solanacol, solanacyl acetate, strigol, strigone, strigyl acetate, 5-deoxystrigol, sorgomol, sorgolactone, methyl 16-hydroxycarlactonate, methyl 4-hydroxycarlactonate, 1'-Hydroxymethyl carlactonate, 1'-Hydroxymethyl carlactonate, Methyl carlactonate, or Sphynolactone-7.

[0009] [3] The germination inducer for root parasitic plants according to [1], characterized in that the compound represented by formula (II) is jasmonic acid, isoleucine jasmonate, valine jasmonate, 4,5-didehydrojasmonic acid isoleucine, 9,10-dihydrojasmonic acid valine, 12-oxophytodienoic acid (OPDA), prohydrojasmone (PDJ), or 5'-hydroxypropyl jasmonate (5'-OH-PDJ).

[0010] [4] The germination inducer for root parasitic plants according to [1], characterized in that the compound represented by formula (Ia), formula (Ib), formula (Ic), or formula (Id) is GR24, and the compound represented by formula (II) is jasmonic acid, isoleucine jasmonate, or 12-oxophytodienoic acid (OPDA).

[0011] [5] The germination inducer for root parasitic plants according to [1], characterized in that the root parasitic plant is a plant belonging to the family Orobanchaceae.

[0012] [6] The germination inducer for root parasitic plants according to [1], wherein the root parasitic plant is Striga hermonthica, Striga asiatica, Striga gesnerioides, Orobanche minor, Phelipanche ramosa, or Phelipanche aegyptiaca.

[0013] [7] A method for inducing germination of a root parasitic plant, comprising the following steps (1) and (2): (1) reacting a compound represented by the following formula (Ia), (Ib), (Ic), or (Id): [wherein R1 represents a hydrogen atom or a methyl group, R2 represents a hydrogen atom or a methyl group, R3 represents a hydrogen atom, a hydroxy group, or an acetoxy group, R4 and R5 each independently represent a hydrogen atom, a methyl group, or a hydroxymethyl group, or R4 and R5 together represent a methylene group, R6 represents a hydrogen atom or a methyl group, R7 and R8 each independently represent a hydrogen atom, a hydroxy group, or an acetoxy group, or R7 and R8 together represent an oxygen atom, R9 represents a hydrogen atom, a hydroxy group, or an acetoxy group, R 10 represents a methyl group or a hydroxymethyl group, and R 11 represents a hydrogen atom or a hydroxy group, and R 12represents a methyl group or a hydroxymethyl group, and the dotted triangle with an oxygen atom in formula (Ib) indicates the presence of either a double bond or an epoxide.] to soil containing seeds of a root parasitic plant; [In the formula, R 13 -CH2-COOH, -CH2-COOR 15 (However, R 15 represents an amino acid residue or an alkyl group having 1 to 4 carbon atoms, or -(CH2)7-COOH, and R 14 represents a hydrogen atom or a hydroxy group, and the double line portion consisting of a solid line and a dotted line represents a single bond or a double bond.] to soil containing seeds of a root parasitic plant.

[0014] [8] The compound represented by formula (Ia), formula (Ib), formula (Ic), or formula (Id) is GR24, fabacol, fabasyl acetate, 4-deoxyorobanchol, phelipanchol, orobancil acetate, orobanchol, solanacol, solanacyl acetate, strigol, strigone, strigyl acetate, 5-deoxystrigol, sorgomol, sorgolactone, methyl 16-hydroxy carlactonate, methyl 4-hydroxy carlactonate, 8. The method for inducing germination of a root parasitic plant according to claim 7, wherein the compound is 1'-hydroxymethyl carlactonate, 1'-hydroxymethyl carlactonate, methyl carlactonate, or sphynolactone-7.

[0015] [9] The method for inducing germination of a root parasitic plant according to [7], wherein the compound represented by formula (II) is jasmonic acid, isoleucine jasmonate, valine jasmonate, 4,5-didehydrojasmonic acid isoleucine, 9,10-dihydrojasmonic acid valine, 12-oxophytodienoic acid (OPDA), prohydrojasmone (PDJ), or 5'-hydroxypropyl jasmonate (5'-OH-PDJ).

[0016]

[10] The method for inducing germination of a root parasitic plant according to [7], characterized in that the compound represented by formula (Ia), formula (Ib), formula (Ic), or formula (Id) is GR24, and the compound represented by formula (II) is jasmonic acid, isoleucine jasmonate, or 12-oxophytodienoic acid (OPDA).

[0017]

[11] The method for inducing germination of a root parasitic plant according to [7], wherein the root parasitic plant is a plant belonging to the family Orobanchaceae.

[0018]

[12] The method for inducing germination of a root parasitic plant according to [7], wherein the root parasitic plant is Striga hermonthica, Striga asiatica, Striga gesnerioides, Orobanche minor, Phelipanche ramosa, or Phelipanche aegyptiaca.

[0019] The present invention provides a novel germination inducer for root parasitic plants, which is useful for controlling root parasitic plants.

[0020] 1. A diagram showing the results of a germination test for Orobanche minor seeds. 2. A diagram showing the results of a germination test for Striga hermonthica seeds. 3. A diagram showing the comparison of seed germination rates when GR24 was added alone, OPDA was added alone, and a mixture of GR24 and OPDA was added.

[0021] (A) Germination inducer for root parasitic plants The germination inducer for root parasitic plants of the present invention is characterized by containing strigolactones and jasmonates as active ingredients.

[0022] In the present invention, strigolactones are compounds represented by the following formula (Ia), (Ib), (Ic), or (Id): The compound includes compounds represented by the formula:

[0023] In formula (Ia), R1 represents a hydrogen atom or a methyl group, preferably a hydrogen atom. In formula (Ia), R2 represents a hydrogen atom or a methyl group, preferably a hydrogen atom. In formula (Ia), R3 represents a hydrogen atom, a hydroxy group, or an acetoxy group, preferably a hydrogen atom. In formula (Ib), R4 and R5 each independently represent a hydrogen atom, a methyl group, or a hydroxymethyl group, or R4 and R5 together represent a methylene group, preferably both represent a methyl group. In formula (Ib), R6 represents a hydrogen atom or a methyl group, preferably a hydrogen atom. In formula (Ib), R7 and R8 each independently represent a hydrogen atom, a hydroxy group, or an acetoxy group, or R7 and R8 together represent an oxygen atom, preferably both represent a hydrogen atom. In formula (Ib), R9 represents a hydrogen atom, a hydroxy group, or an acetoxy group, preferably a hydrogen atom. In formula (Ib), the dotted triangle with the oxygen atom indicates the presence of either a double bond or an epoxide, but preferably indicates the presence of a double bond. 10 represents a methyl group or a hydroxymethyl group, and preferably represents a methyl group. 11 represents a hydrogen atom or a hydroxy group, preferably a hydrogen atom. 12 represents a methyl group or a hydroxymethyl group, and preferably represents a methyl group.

[0024] The compounds represented by formula (Ia), (Ib), (Ic), or (Id) have isomers. For example, the compounds represented by formula (Ib) include strigol-type compounds represented by the following formula (Ib-1) and orobanchol-type compounds represented by the following formula (Ib-2). The compounds represented by formula (Ia), (Ib), (Ic), or (Id) also include such isomers.

[0025] Specific examples of the compound represented by formula (Ia) include GR24, Solanacol, and Solanacyl acetate. Specific examples of the compound represented by formula (Ib) include Fabacol, Fabasyl acetate, 4-Deoxyorobanchol, Phelipanchol, Orobancyl acetate, Orobanchol, Strigol, Strigone, Strigyl acetate, 5-Deoxystrigol, Sorgomol, and Sorgolactone. Specific examples of the compound represented by formula (Ic) include Methyl 16-hydroxy carlactonate and Methyl 4-hydroxy carlactonate. Examples of the compound represented by formula (Id) include 1'-hydroxymethyl carlactonate, 1'-hydroxymethyl carlactonate, and methyl carlactonate, and a specific example of the compound represented by formula (Id) is sphynolactone-7.

[0026] The compounds represented by formula (Ia), (Ib), (Ic), and (Id) are commercially available. Even if they are not commercially available, those skilled in the art can prepare them according to known literature.

[0027] In the present invention, jasmonic acids are represented by the following formula (II): The compound includes compounds represented by the formula:

[0028] In formula (II), R 13 -CH2-COOH, -CH2-COOR 15 or -(CH2)7-COOH. 15 represents an amino acid residue or an alkyl group having 1 to 4 carbon atoms. Here, "amino acid residue" means a group in which one hydrogen atom has been removed from the amino group of an amino acid. Furthermore, "alkyl group having 1 to 4 carbon atoms" refers to a methyl group, ethyl group, n-propyl group, n-butyl group, etc. R 13 may be any of the groups described above, but is preferably -CH2-COOH, -CH2-COO-valine residue, -CH2-COO-isolosine residue, -(CH2)7-COOH, or -CH2-COO-C3H7, and more preferably CH2-COOH, -CH2-COO-isolosine residue, or -(CH2)7-COOH. 14 represents a hydrogen atom or a hydroxy group, preferably a hydrogen atom. In formula (II), the double line consisting of a solid line and a dotted line represents a single bond or a double bond.

[0029] Specific examples of the compound represented by formula (II) include jasmonic acid, isoleucine jasmonate, valine jasmonate, 4,5-didehydrojasmonic acid isoleucine, 9,10-dihydrojasmonic acid valine, 12-oxophytodienoic acid (OPDA), prohydrojasmone (PDJ), and 5'-hydroxypropyl jasmonate (5'-OH-PDJ).

[0030] The compound represented by formula (II) is commercially available, and even if it is not commercially available, it can be prepared by a person skilled in the art according to known literature.

[0031] The mixing ratio of strigolactones to jasmonic acids is not particularly limited, but the molar ratio of strigolactones / jasmonic acids is preferably 1 / 1,000.0 to 1 / 100, and more preferably 1 / 100.0 to 1 / 200.

[0032] The germination inducer for root parasitic plants of the present invention can be used in a "suicidal germination induction method." That is, the germination inducer for root parasitic plants of the present invention is sprayed into soil in the absence of a host plant of the root parasitic plant to forcibly germinate the seeds of the root parasitic plant, thereby preventing the root parasitic plant from receiving nutrients from the host plant, and the root parasitic plant can be controlled.

[0033] The root parasitic plant is not particularly limited, but is preferably a plant belonging to the family Orobanchaceae, and more preferably Striga hermonthica, Striga asiatica, Striga gesnerioides, Orobanche minor, Phelipanche ramose, or Phelipanche aegyptiaca. Examples of host plants for root parasitic plants include grasses such as corn and sorghum, legumes such as cowpea, and solanaceae plants such as tobacco.

[0034] The germination inducer for root parasitic plants of the present invention, like general pesticides, can be formulated in a conventional manner by combining strigolactones and jasmonic acids with carriers, surfactants, adhesives, dispersants, stabilizers, etc., and formulating them into dusts, microgranules, granules, emulsifiable concentrates, wettable powders, suspensions, dry flowables, flowables, aqueous liquids, oils, smoke preparations, aerosols, or microcapsules.

[0035] The carrier may be either a solid carrier or a liquid carrier. Examples of solid carriers include fine powders or granules of clays (e.g., kaolinite, acid clay, diatomaceous earth, synthetic hydrous silicon oxide, bentonite), talc, other inorganic minerals (e.g., calcium carbonate, quartz powder, activated carbon, hydrated silica), chemical fertilizers (e.g., ammonium sulfate, ammonium chloride, ammonium phosphate, urea), and organic substances (e.g., sugarcane, bark powder, tobacco stalk powder). Examples of liquid carriers include water, alcohols (e.g., methanol, ethanol, isopropanol), ketones (e.g., acetone, methyl ethyl ketone), hydrocarbons (e.g., benzene, toluene, xylene, cyclohexane, methylnaphthalene), esters (e.g., ethyl acetate, butyl acetate), ethers (e.g., dioxane, diisopropyl ether), and acid amides (e.g., dimethylformamide, dimethylacetamide).

[0036] Examples of surfactants include alkyl sulfates, alkyl sulfonates, alkylaryl sulfonates, alkylaryl ethers and their polyoxyethylenated derivatives, polyethylene glycol ethers, polyhydric alcohol esters, and sugar alcohol derivatives.

[0037] Examples of binders and dispersants include casein, gelatin, polysaccharides (e.g., starch, gum arabic, cellulose derivatives), lignin derivatives, bentonite, sugars, and synthetic water-soluble polymers (e.g., polyvinyl alcohol, polyvinylpyrrolidone, polyacrylic acids).

[0038] The stabilizer may include isopropyl acid phosphate, 2,6-di-t-butyl-4-methylphenol, vegetable oil, mineral oil, fatty acid, or esters thereof.

[0039] The amount of the germination inducer for root parasitic plants of the present invention to be sprayed is not particularly limited, but it is preferable to spray strigolactones at 100 μg to 10 mg, and more preferably 500 μg to 5 mg, per 10 are, and it is preferable to spray jasmonic acids at 100 mg to 10 g, and more preferably 500 mg to 5 g.

[0040] (B) Method for inducing germination of root parasitic plants The method for inducing germination of root parasitic plants of the present invention is characterized by comprising the following steps (1) and (2):

[0041] In step (1), strigolactones are applied to soil containing seeds of root parasitic plants. The strigolactones and the amounts applied may be the same as those used for the root parasitic plant germination inducers described above. The soil to which strigolactones are applied is the same soil to which jasmonic acids are applied in step (2).

[0042] In step (2), jasmonic acids are sprayed onto the soil containing the seeds of the root parasitic plants. The jasmonic acids and the amount to be sprayed may be the same as those used for the germination inducer for root parasitic plants described above.

[0043] Step (1) and step (2) may be carried out simultaneously, or step (1) may be carried out first and then step (2), or conversely, step (2) may be carried out first and then step (1).

[0044] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0045] (1) Materials and methods: Root parasitic plant materials: Orobanche minor seeds collected from the Nagasawa Water Purification Plant in Kawasaki, Kanagawa Prefecture, and Striga hermonthica seeds collected in Kenya.

[0046] Germination test using O. minor and S. hermonthica seeds. Seed sterilization: O. minor or S. hermonthica seeds were added to a 50 mL tube up to just below the 5 mL mark. 30 mL of 70% EtOH was added and the tube was sonicated for 1 minute. The supernatant was discarded, and 30 mL of sterilization solution (sodium hypochlorite with a final available chlorine concentration of 0.2%, 0.2% Tween-20) was added and the tube was sonicated for 4 minutes. The sterilized seeds were vacuum filtered using a Buchner funnel in a clean bench, and the seeds on the filter paper were washed with 1 L of sterile water. After drying, the seeds were transferred to a 50 mL tube and stored at room temperature.

[0047] Conditioning and germination test of O. minor seeds: Three to four microspatulafuls of sterilized seeds were placed in a 1.5 mL tube, and 1 mL of 0.1% water agar solution was added. The seeds were then germinated for 2 to 3 days. o The dish was left in the dark for 30 min. A 70 mm filter paper was placed on the dish, moistened with 1 mL of sterile water, and then a 5 mm diameter glass fiber filter paper disk was placed on top. 20 to 70 O. minor seeds suspended in 0.1% water-agar solution were dispensed onto the disk. 23 o The seeds were then left to stand in the dark for 12-13 days. After conditioning, the seeds were transferred to a 96-well plate along with the disks, and 30 μL of the test solution was dispensed into each well. Acetone was used to prepare a stock solution of the compound, which was then diluted with sterile water to prepare the solution used in the germination test (the final acetone concentration of the test solution was 0.1%). The 96-well plate was sealed with parafilm and left for 23 o After incubation in the dark for 5 days, the total number of seeds and germinated seeds were counted under a microscope, and the germination rate was calculated.

[0048] Conditioning and germination test of S. hermonthica seeds: Three to four microspatulafuls of sterilized seeds were placed in a 1.5 mL tube, and 1 mL of 0.1% water agar solution was added. The seeds were then germinated for 1 to 2 days, 30 days, and 100 mL of water agar solution was added. oThe dish was left in the dark for 30 minutes. A 70 mm filter paper was placed on the dish, moistened with 1 mL of sterile water, and then a 5 mm diameter glass fiber filter paper disk was placed on top of the filter paper. 20 to 70 seeds of S. hermonthica suspended in 0.1% water agar solution were dispensed onto the disk. o The seeds were then placed in a dark place for 5-6 days. After conditioning, the seeds were transferred to a 96-well plate along with the disks, and 30 μL of the test solution was dispensed into each well. Acetone was used to prepare a stock solution of the compounds, which was then diluted with sterile water to prepare the test solution used in the germination test (the final acetone concentration of the test solution was 0.1%). The 96-well plate was sealed with parafilm and left for 30 minutes. o After incubation in the dark for 1 day, the total number of seeds and germinated seeds were counted under a microscope, and the germination rate was calculated.

[0049] (2) Results The germination rates of seeds treated with GR24 and jasmonates are shown in Figure 1 (Orobanche minor) and Figure 2 (Striga hermonthica). The jasmonates used were 12-oxophytodienoic acid (OPDA), jasmonic acid (JA), and jasmonate-isoleucine (JA-Ile). Figure 3 compares the germination rates of seeds treated with GR24 alone, OPDA alone, and a mixture of GR24 and OPDA. As shown in Figures 1 to 3, the germination rate was synergistically improved by the addition of a mixture of GR24 and jasmonates. The improvement in germination rate was particularly significant for Orobanche minor.

[0050] The present invention can be used in the agricultural field.

Claims

1. A compound represented by the following formula (Ia), (Ib), (Ic), or (Id): [wherein R1 represents a hydrogen atom or a methyl group, R2 represents a hydrogen atom or a methyl group, R3 represents a hydrogen atom, a hydroxy group, or an acetoxy group, R4 and R5 each independently represent a hydrogen atom, a methyl group, or a hydroxymethyl group, or R4 and R5 together represent a methylene group, R6 represents a hydrogen atom or a methyl group, R7 and R8 each independently represent a hydrogen atom, a hydroxy group, or an acetoxy group, or R7 and R8 together represent an oxygen atom, R9 represents a hydrogen atom, a hydroxy group, or an acetoxy group, R 10 represents a methyl group or a hydroxymethyl group, and R 11 represents a hydrogen atom or a hydroxy group, and R 12 represents a methyl group or a hydroxymethyl group, and the dotted triangle with an oxygen atom in formula (Ib) indicates the presence of either a double bond or an epoxide. [In the formula, R 13 -CH2-COOH, -CH2-COOR 15 (However, R 15 represents an amino acid residue or an alkyl group having 1 to 4 carbon atoms, or -(CH2)7-COOH, and R 14 represents a hydrogen atom or a hydroxy group, and the double line portion consisting of a solid line and a dotted line represents a single bond or a double bond.

2. The compound represented by the following formula (Ia), (Ib), (Ic), or (Id) is GR24, fabacol, fabasyl acetate, 4-deoxyorobanchol, phelipanchol, orobancil acetate, orobanchol, solanacol, solanacyl acetate, strigol, strigone, strigyl acetate, 5-deoxystrigol, sorgomol, sorgolactone, methyl 16-hydroxy carlactonate, methyl 4-hydroxy carlactonate, orobanchol, solanacol, solanacyl acetate, strigol, strigone, strigyl acetate, 5-deoxystrigol, sorgomol, sorgolactone, methyl 16-hydroxy carlactonate, orobanchol, solanacol, solanacyl acetate, strigol, strigone, strigyl acetate, 5-deoxystrigol, sorgomol, sorgolactone, methyl 16-hydroxy carlactonate, orobanchol, solanacol, solanacyl acetate, strigol, strigone, strigyl acetate, 5-deoxystrigol, sol ...solgolactone, methyl 16-hydroxy carlactonate 2. The germination inducer for root parasitic plants according to claim 1, characterized in that the germination inducer is selected from the group consisting of 1'-hydroxymethyl carlactonate, 1'-hydroxymethyl carlactonate, methyl carlactonate, and sphynolactone-7.

3. A germination inducer for root parasitic plants according to claim 1, characterized in that the compound represented by formula (II) is jasmonic acid, isoleucine jasmonate, valine jasmonate, 4,5-didehydrojasmonic acid isoleucine, 9,10-dihydrojasmonic acid valine, 12-oxophytodienoic acid (OPDA), prohydrojasmone (PDJ), or 5'-hydroxypropyl jasmonate (5'-OH-PDJ).

4. A germination inducer for root parasitic plants according to claim 1, characterized in that the compound represented by formula (Ia), formula (Ib), formula (Ic), or formula (Id) is GR24, and the compound represented by formula (II) is jasmonic acid, isoleucine jasmonate, or 12-oxophytodienoic acid (OPDA).

5. A germination inducer for root parasitic plants according to claim 1, characterized in that the root parasitic plant is a plant belonging to the Orobanchaceae family.

6. The germination inducer for root parasitic plants according to claim 1, characterized in that the root parasitic plant is Striga hermonthica, Striga asiatica, Striga gesnerioides, Orobanche minor, Phelipanche ramosa, or Phelipanche aegyptiaca.

7. A method for inducing germination of a root parasitic plant, comprising the following steps (1) and (2): (1) reacting a compound represented by the following formula (Ia), (Ib), (Ic), or (Id): [wherein R1 represents a hydrogen atom or a methyl group, R2 represents a hydrogen atom or a methyl group, R3 represents a hydrogen atom, a hydroxy group, or an acetoxy group, R4 and R5 each independently represent a hydrogen atom, a methyl group, or a hydroxymethyl group, or R4 and R5 together represent a methylene group, R6 represents a hydrogen atom or a methyl group, R7 and R8 each independently represent a hydrogen atom, a hydroxy group, or an acetoxy group, or R7 and R8 together represent an oxygen atom, R9 represents a hydrogen atom, a hydroxy group, or an acetoxy group, R 10 represents a methyl group or a hydroxymethyl group, and R 11 represents a hydrogen atom or a hydroxy group, and R 12 represents a methyl group or a hydroxymethyl group, and the dotted triangle with an oxygen atom in formula (Ib) indicates the presence of either a double bond or an epoxide.] to soil containing seeds of a root parasitic plant; [In the formula, R 13 -CH2-COOH, -CH2-COOR 15 (However, R 15 represents an amino acid residue or an alkyl group having 1 to 4 carbon atoms, or -(CH2)7-COOH, and R 14 represents a hydrogen atom or a hydroxy group, and the double line portion consisting of a solid line and a dotted line represents a single bond or a double bond.] to soil containing seeds of a root parasitic plant.

8. The compound represented by formula (Ia), formula (Ib), formula (Ic), or formula (Id) is GR24, fabacol, fabasyl acetate, 4-deoxyorobanchol, phelipanchol, orobancil acetate, orobanchol, solanacol, solanacyl acetate, strigol, strigone, strigyl acetate, 5-deoxystrigol, sorgomol, sorgolactone, methyl 16-hydroxy carlactonate, methyl 4-hydroxy carlactonate, or 8. The method for inducing germination of root parasitic plants according to claim 7, characterized in that the germination inhibitor is 1'-hydroxymethyl carlactonate, 1'-hydroxymethyl carlactonate, methyl carlactonate, or sphynolactone-7.

9. A method for inducing germination of root parasitic plants as described in claim 7, characterized in that the compound represented by formula (II) is jasmonic acid, isoleucine jasmonate, valine jasmonate, 4,5-didehydrojasmonic acid isoleucine, 9,10-dihydrojasmonic acid valine, 12-oxophytodienoic acid (OPDA), prohydrojasmone (PDJ), or 5'-hydroxypropyl jasmonate (5'-OH-PDJ).

10. A method for inducing germination of a root parasitic plant as described in claim 7, characterized in that the compound represented by formula (Ia), formula (Ib), formula (Ic), or formula (Id) is GR24, and the compound represented by formula (II) is jasmonic acid, isoleucine jasmonate, or 12-oxophytodienoic acid (OPDA).

11. The method for inducing germination of a root parasitic plant according to claim 7, wherein the root parasitic plant is a plant belonging to the family Orobanchaceae.

12. The method for inducing germination of a root parasitic plant according to claim 7, wherein the root parasitic plant is Striga hermonthica, Striga asiatica, Striga gesnerioides, Orobanche minor, Phelipanche ramosa, or Phelipanche aegyptiaca.

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