Plant crown gall control agent and plant crown gall control method

Abstract

To provide a novel control agent and a novel control method for plant crown gall.SOLUTION: A plant crown gall control agent includes viroid as an active ingredient. Viroid preferably has infection ability to a plant to be controlled, and may be an asymptomatic kind with respect to the plant. The plant may be fruit trees, ornamental flowers, or vegetables.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a plant crown gall disease control agent and a plant crown gall disease control method. [Background technology]

[0002] Crown gall disease is a disease caused by Rhizobium bacteria that causes galls called cankers (cancers, crown galls) to form on the roots and stems of plants. Hereinafter, the causative bacteria that cause crown gall disease will also be referred to as "crown gall fungus."

[0003] The crown gall fungus invades plants through wounds. Its host range (infection area) is wide, and it causes disease in fruit trees such as apples, peaches, pears, and cherries, as well as flowers such as chrysanthemums, and vegetables such as tomatoes and potatoes, causing stunted growth and death. In particular, fruit trees suffer from a decline in tree vigor and a deterioration in fruit quality, and seedlings and young trees often die the year after the onset of the disease.

[0004] For example, Non-Patent Document 1 discloses the results of an analysis of Allorhizobium vitis (synonyms: Rhizobium vitis, Agrobacterium vitis, Agrobacterium tumefaciens biovar 3) strains, which are a type of crown gall fungus that infects grapevines.

[0005] This non-patent document 1 describes that multilocus sequence analysis (MLSA) was performed on the above-mentioned crown gall fungus, and seven genome groups were obtained, and that in Hokkaido, the sources of infection are soil infection and the transportation of infected seedlings.

[0006] The biological pesticide "Bacterose" (registered trademark, Nihon Nohyaku Co., Ltd.), which contains Agrobacterium radiobacter, has been sold as an effective pesticide against crown gall disease. This pesticide is able to kill the crown gall bacteria using the antibacterial substances produced by Agrobacterium radiobacter. [Prior art documents] [Non-patent literature]

[0007] [Non-Patent Document 1] Kawaguchi A. et al., Origin of Pathogens of Grapevine Crown Gall Disease in Hokkaido in Japan as Characterized by Molecular Epidemiology of Allorhizobium vitis Strains. Life, 11(11), 1265, 2021. Summary of the Invention [Problem to be solved by the invention]

[0008] However, the above pesticides are not effective against the crown gall fungus that infects grapes, and as of 2024, production and sales of these pesticides have been discontinued.

[0009] In addition, the crown gall fungus spreads through soil and contact infection and can survive in the soil for a long period of time. Therefore, when crown gall occurs in a plant, the soil around the infected plant must be removed to prevent infection when replanting, but it is difficult to completely remove soil containing the crown gall fungus. Therefore, there is currently a need for a viable solution to crown gall disease.

[0010] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a novel agent and method for controlling crown gall disease of plants. [Means for solving the problem]

[0011] The present inventors have discovered that the onset of crown gall disease, i.e., the formation of cancers caused by the crown gall fungus, can be suppressed by inoculating plants with a viroid consisting of RNA, and have completed the present invention. That is, one aspect of the present invention that solves the above-mentioned problems includes the following aspects.

[0012] [1] A plant crown gall disease control agent containing a viroid as an active ingredient.

[0013] [2] The plant crown gall disease control agent according to [1], wherein the viroid has the ability to infect a target plant against which crown gall disease is to be controlled.

[0014] [3] The plant crown gall disease control agent according to [1] or [2], wherein the viroid is a species that is asymptomatic in plants.

[0015] [4] The plant crown gall disease control agent according to any one of [1] to [3], wherein the plant is a fruit tree, a flowering plant, or a vegetable.

[0016] [5] The plant crown gall disease control agent according to any one of [1] to [4], wherein the plant is a chrysanthemum.

[0017] [6] The plant crown gall disease control agent according to any one of [1] to [5], wherein the plant is a plant of the Solanaceae family.

[0018] [7] The plant crown gall disease control agent according to any one of [1] to [6], wherein the plant is a tomato.

[0019] [8] The plant crown gall disease control agent according to [6] or [7], wherein the viroid is one or more RNAs selected from the group consisting of T1 to T12 below. (T1) RNA having the base sequence shown in SEQ ID NO: 1. (T2) RNA having a base sequence in which one or more bases have been deleted, substituted, added or inserted in a region other than the two regions of the base sequence shown in SEQ ID NO: 1, namely the region consisting of the base sequence shown in SEQ ID NO: 2 and the region consisting of the base sequence shown in SEQ ID NO: 3. (T3) RNA having a base sequence having 85% or more sequence identity with the base sequence shown in SEQ ID NO: 1, and including a region consisting of the base sequence shown in SEQ ID NO: 2 and a region consisting of the base sequence shown in SEQ ID NO: 3. (T4) RNA having the base sequence shown in SEQ ID NO: 4. (T5) RNA having a base sequence in which one or more bases have been deleted, substituted, added or inserted in a region other than the two regions of the base sequence shown in SEQ ID NO: 4, namely the region consisting of the base sequence shown in SEQ ID NO: 5 and the region consisting of the base sequence shown in SEQ ID NO: 6. (T6) RNA having a base sequence having 85% or more sequence identity with the base sequence shown in SEQ ID NO: 4, and including a region consisting of the base sequence shown in SEQ ID NO: 2 and a region consisting of the base sequence shown in SEQ ID NO: 3. (T7) RNA having the base sequence shown in SEQ ID NO: 7. (T8) RNA having a base sequence in which one or more bases have been deleted, substituted, added or inserted in a region other than the two regions consisting of the base sequence shown in SEQ ID NO: 7, namely the region consisting of the base sequence shown in SEQ ID NO: 8 and the region consisting of the base sequence shown in SEQ ID NO: 9. (T9) A base sequence having 85% or more sequence identity with the base sequence shown in SEQ ID NO: 7, comprising a region consisting of the base sequence shown in SEQ ID NO: 8 and a region consisting of the base sequence shown in SEQ ID NO: 9. (T10) RNA having the base sequence shown in SEQ ID NO: 10. (T11) RNA having a base sequence in which one or more bases have been deleted, substituted, added or inserted in a region other than the two regions consisting of the base sequence shown in SEQ ID NO: 10, namely the region consisting of the base sequence shown in SEQ ID NO: 11 and the region consisting of the base sequence shown in SEQ ID NO: 12. (T12) A base sequence having 85% or more sequence identity with the base sequence shown in SEQ ID NO: 10, comprising a region consisting of the base sequence shown in SEQ ID NO: 11 and a region consisting of the base sequence shown in SEQ ID NO: 12.

[0020] [9] The crown gall disease control agent according to [6] or [7], wherein the viroid is one or more viroids selected from the group consisting of potato spindle tuber viroid (PSTVd), chrysanthemum stunt viroid (CSVd), and hop latent viroid (HpLVd).

[0021]

[10] The plant crown gall disease control agent according to any one of [1] to [4], wherein the viroid is one or more RNAs selected from the group consisting of G1 to G15 below, and the plant is a Vitaceae plant. (G1) RNA having the base sequence shown in SEQ ID NO: 13. (G2) RNA having a base sequence in which one or more bases have been deleted, substituted, added or inserted in a region other than the two regions of the base sequence shown in SEQ ID NO: 13, namely, the region consisting of the base sequence shown in SEQ ID NO: 14 and the region consisting of the base sequence shown in SEQ ID NO: 15. (G3) A base sequence having 85% or more sequence identity with the base sequence shown in SEQ ID NO: 13, comprising a region consisting of the base sequence shown in SEQ ID NO: 14 and a region consisting of the base sequence shown in SEQ ID NO: 15. (G4) RNA having the base sequence shown in SEQ ID NO: 16. (G5) RNA having a base sequence in which one or more bases have been deleted, substituted, added or inserted in a region other than the two regions of the base sequence shown in SEQ ID NO: 16, namely, the region consisting of the base sequence shown in SEQ ID NO: 17 and the region consisting of the base sequence shown in SEQ ID NO: 18. (G6) A base sequence having 85% or more sequence identity with the base sequence shown in SEQ ID NO: 16, comprising a region consisting of the base sequence shown in SEQ ID NO: 17 and a region consisting of the base sequence shown in SEQ ID NO: 18. (G7) RNA having the base sequence shown in SEQ ID NO: 19. (G8) RNA having a base sequence in which one or more bases have been deleted, substituted, added or inserted in a region other than the two regions of the base sequence shown in SEQ ID NO: 19, namely, the region consisting of the base sequence shown in SEQ ID NO: 20 and the region consisting of the base sequence shown in SEQ ID NO: 21. (G9) A base sequence having 85% or more sequence identity with the base sequence shown in SEQ ID NO: 19, comprising a region consisting of the base sequence shown in SEQ ID NO: 20 and a region consisting of the base sequence shown in SEQ ID NO: 21. (G10) RNA having the base sequence shown in SEQ ID NO: 22. (G11) RNA having a base sequence in which one or more bases have been deleted, substituted, added or inserted in a region of the base sequence shown in SEQ ID NO: 22 other than the region consisting of the base sequence shown in SEQ ID NO: 23. (G12) An RNA having a base sequence having 85% or more sequence identity with the base sequence shown in SEQ ID NO: 22 and containing a region consisting of the base sequence shown in SEQ ID NO: 23. (G13) RNA having the base sequence shown in SEQ ID NO: 24. (G14) RNA having a base sequence in which one or more bases have been deleted, substituted, added or inserted in a region of the base sequence shown in SEQ ID NO: 24 other than the region consisting of the base sequence shown in SEQ ID NO: 25. (G15) An RNA having a base sequence having 85% or more sequence identity with the base sequence shown in SEQ ID NO: 24, and comprising a region consisting of the base sequence shown in SEQ ID NO: 25.

[0022]

[11] The plant crown gall disease control agent according to any one of [1] to [4], wherein the viroid is one or more viroids selected from the group consisting of hop dwarf viroid (HpSVd), grapevine yellow speckle viroid 1 (GYSVd-1), citrus exocortis viroid (CEVd), grapevine yellow speckle viroid 2 (GYSVd-2), and grapevine Australian viroid (AGVd), and the plant is a Vitaceae plant.

[0023]

[12] The plant crown gall disease control agent according to any one of [1] to [5], wherein the viroid is one or more RNAs selected from the group consisting of T1 to T9 below, and the plant is an Asteraceae plant. (T1) RNA having the base sequence shown in SEQ ID NO: 1. (T2) RNA having a base sequence in which one or more bases have been deleted, substituted, added or inserted in a region other than the two regions of the base sequence shown in SEQ ID NO: 1, namely the region consisting of the base sequence shown in SEQ ID NO: 2 and the region consisting of the base sequence shown in SEQ ID NO: 3. (T3) RNA having a base sequence having 85% or more sequence identity with the base sequence shown in SEQ ID NO: 1, and including a region consisting of the base sequence shown in SEQ ID NO: 2 and a region consisting of the base sequence shown in SEQ ID NO: 3. (T4) RNA having the base sequence shown in SEQ ID NO: 4. (T5) RNA having a base sequence in which one or more bases have been deleted, substituted, added or inserted in a region other than the two regions of the base sequence shown in SEQ ID NO: 4, namely the region consisting of the base sequence shown in SEQ ID NO: 5 and the region consisting of the base sequence shown in SEQ ID NO: 6. (T6) A base sequence having 85% or more sequence identity with the base sequence shown in SEQ ID NO: 4, and an RNA comprising a region consisting of the base sequence shown in SEQ ID NO: 5 and a region consisting of the base sequence shown in SEQ ID NO: 6. (T7) RNA having the base sequence shown in SEQ ID NO: 7. (T8) RNA having a base sequence in which one or more bases have been deleted, substituted, added or inserted in a region other than the two regions consisting of the base sequence shown in SEQ ID NO: 7, namely the region consisting of the base sequence shown in SEQ ID NO: 8 and the region consisting of the base sequence shown in SEQ ID NO: 9. (T9) A base sequence having 85% or more sequence identity with the base sequence shown in SEQ ID NO: 7, comprising a region consisting of the base sequence shown in SEQ ID NO: 8 and a region consisting of the base sequence shown in SEQ ID NO: 9.

[0024]

[13] The plant crown gall disease control agent according to any one of [1] to [5], wherein the viroid is one or more viroids selected from the group consisting of potato spindle tuber viroid (PSTVd) and chrysanthemum stunt viroid (CSVd), and the plant is an Asteraceae plant.

[0025]

[14] A method for controlling crown gall disease in plants, comprising the step of inoculating a plant with the agent for controlling crown gall disease in plants according to any one of [1] to

[13] .

[0026]

[15] The method for controlling crown gall disease in plants according to

[14] , wherein the plants are fruit trees, ornamental plants, or vegetables. [Effects of the Invention]

[0027] According to the present invention, the onset of crown gall disease, i.e., the formation of cancers caused by the crown gall fungus, can be suppressed by inoculating a plant with a viroid, and therefore a novel agent and method for controlling crown gall disease can be provided. [Brief explanation of the drawings]

[0028] [Figure 1] FIG. 1 is a schematic diagram of an experimental example. [Figure 2] This is an image showing the stem of a cherry tomato inoculated with crown gall fungus. [Figure 3] 1 is a graph showing the diameter distribution and average diameter of the carcinoma 1 formed in the CSVd tomato (cherry tomato) and the diameter distribution and average diameter of the carcinoma 1 formed in the healthy tomato (cherry tomato). [Figure 4] This is an image showing a stem of Rutgers inoculated with crown gall fungus. [Figure 5] 1 is a graph showing the diameter distribution and average diameter of cancers formed in the CSVd tomatoes (Rutgers) and the diameter distribution and average diameter of cancers formed in the healthy tomatoes (Rutgers). [Figure 6] 1 is a graph showing the diameter distribution and mean diameter of carcinomas formed in PSTVd(VP69-2) tomatoes, the diameter distribution and mean diameter of carcinomas formed in PSTVd(VP72-1) tomatoes, and the diameter distribution and mean diameter of carcinomas formed in healthy tomatoes. [Figure 7] 1 is a graph showing the diameter distribution and average diameter of cankers formed on CSVd-infected chrysanthemums and the diameter distribution and average diameter of cankers formed on non-CSVd-infected chrysanthemums in test plots inoculated with the VAT03-9 strain of Allorhizobium vitis. [Figure 8]1 is a graph showing the diameter distribution and average diameter of cankers formed in CSVd-infected chrysanthemums and the diameter distribution and average diameter of cankers formed in non-CSVd-infected chrysanthemums in test plots inoculated with the VAT21-19 strain of Allorhizobium vitis. DETAILED DESCRIPTION OF THE INVENTION

[0029] [Control agent for crown gall disease in plants] Preferred embodiments of the present invention will now be described in detail.

[0030] A preferred embodiment of the present invention provides a plant crown gall disease control agent that contains a viroid as an active ingredient. In this specification, viroid refers to RNA that has the ability to infect a target plant (in other words, the ability to replicate in the body of a target plant).

[0031] As will be described in detail later in the Examples, the onset of crown gall disease, i.e., the formation of gall tumors, can be effectively suppressed by inoculating and infecting plants with a viroid. Therefore, for example, by inoculating seedlings with a viroid, it is possible to suppress the formation of galls caused by the crown gall fungus after planting in a field, thereby avoiding various symptoms and death of the plant due to gall formation. That is, the crown gall disease control agent of this embodiment uses a viroid as a vaccine for plants, thereby reducing or preventing damage caused by the crown gall disease fungus during the subsequent cultivation period.

[0032] For example, in perennial crops such as fruit trees such as grapes and ornamental plants such as roses, once the crown gall disease control agent of this embodiment is inoculated, it is possible to increase the number of seedlings infected with the viroid by vegetative propagation such as cuttings. It has not been known that plant diseases can be suppressed by inoculation with a viroid.

[0033] The crown gall fungus generally infects and causes disease in dicotyledonous plants. There are several types of crown gall fungus, with the three most common species being: Rhizobium radiobacter (synonym: Agrobacterium radiobacter, Agrobacterium tumefaciens, Agrobacterium tumefaciens biovar 1) Rhizobium rhizogenes (synonym: Agrobacterium rhizogenes, Agrobacterium tumefaciens biovar 2) Allorhizobium vitis (synonyms: Rhizobium vitis, Agrobacterium vitis, Agrobacterium tumefaciens biovar 3)

[0034] Although the susceptibility of the three types of crown gall fungi mentioned above varies at the species and strain level, it is believed that all of the fungi can experimentally infect any dicotyledonous plant, regardless of the plant type. Viroid inoculation is expected to be effective in controlling crown gall caused by any of the fungal species.

[0035] Without being bound by any particular theory, it is thought that when a viroid is inoculated into a plant, it is broken down into short, small RNAs within the plant body, and that these small RNAs exert their inhibitory activity against the crown gall fungus through the action of RNA silencing.

[0036] <<Plants that are subject to crown gall disease control agents>>

[0037] The plant to be inoculated with the crown gall disease control agent of this embodiment may be a plant that is not infected with the crown gall disease fungus, or may be a plant that is already infected with the crown gall disease fungus. If the plant to be inoculated is not infected with the crown gall fungus, inoculation with the crown gall fungicide can prevent or suppress the onset of crown gall. If the plant to be inoculated is infected with the crown gall fungus, inoculation with the crown gall fungicide is expected to completely cure crown gall or alleviate the symptoms and suppress the formation of new cankers.

[0038] The type of plant that is the target of control of crown gall disease using the crown gall disease control agent is not particularly limited, and may be, for example, a vegetable, a fruit tree, or an ornamental plant, such as hops (scientific name: Humulus lupulus) of the Cannabaceae family, chrysanthemums (Asterids), or roses (Rosids).

[0039] (Vegetables) Vegetables include, but are not limited to, plants of the chrysanthemum family, such as solanaceae plants (tomatoes, potatoes, etc.), Asteraceae plants (garland chrysanthemums), and Umbelliferae plants (carrots, etc.).

[0040] (fruit trees) Examples of fruit trees include those belonging to the rose and chrysanthemum families. More specifically, examples include apples, pears, peaches, plums, cherries, plums, and almonds, which belong to the Rosaceae family of the rose family, grapes, which belong to the Vitaceae family of the rose family, and kiwifruit, which belong to the Actinidiaceae family of the chrysanthemum family, but are not limited to these.

[0041] (Flowers) Examples of flowering plants include roses and chrysanthemums. More specifically, examples include, but are not limited to, chrysanthemums (house daisies), daisies, and dahlias of the Asteraceae family of the Asteraceae family, and roses of the Rosaceae family of the Rosaceae family.

[0042] <<Viroids that inoculate plants>> Viroids are RNAs with a length of about 200 to 400 nucleotides. The viroid to be inoculated into plants is not particularly limited as long as it is capable of infecting plants, and its type, base sequence, whether circular or linear, etc. Therefore, for example, it may be a single-stranded linear RNA or a single-stranded circular RNA that has the ability to infect plants to be controlled (in other words, the ability to grow in the plant). Those skilled in the art can appropriately select the type of viroid to be inoculated into plants and that is capable of infecting the plants.

[0043] If the viroid active ingredient has the ability to infect the target plant (in other words, infection activity or replication activity), it will multiply within the plant after inoculation, and the presence of the viroid can be confirmed by Northern hybridization, RT-PCR, or LAMP even 1 to 3 months after inoculation. In contrast, if the viroid active ingredient does not have the ability to infect the target plant, it will decompose without multiplying within the plant, and therefore the viroid will not be detected by Northern hybridization, RT-PCR, or LAMP 1 to 3 months after inoculation. In particular, when the target plant is a fruit tree, it takes time for the viroid to infect it, so it is preferable to check for viroid infection at least 3 months after inoculation.

[0044] In general, viroids have a wide host range (infectious range), but most hosts (plant species) are asymptomatic even when infected by a viroid. For example, chrysanthemum dwarf viroid (CSVd) causes dwarf symptoms when it infects chrysanthemums, but is asymptomatic when it infects tomatoes. For this reason, viroid species that are asymptomatic or produce only slight symptoms (low virulence) when they infect plants can be particularly suitably used as active ingredients for controlling crown gall disease.

[0045] Table 1 below shows examples of plant species that are infected by the crown gall fungus, the crown gall fungus species that have been recorded to naturally infect each plant species or that have been confirmed to infect each plant species experimentally, examples of viroid species that can infect each plant species, and the symptoms of infection in plants with each viroid species. All of the plant species shown in Table 1 are dicotyledonous plants.

[0046] [Table 1] *In Table 1, viroids for which Japanese names could be confirmed are shown by their Japanese names, and viroids for which Japanese names could not be confirmed are shown by their scientific names. * Hop latent viroid (HpLVd) listed in Table 1 is a viroid that is abbreviated as HLVd in some literature. This viroid species can experimentally infect tomato and chrysanthemum. "Experimentally infectable" means that infection can occur by artificially inoculating plants with the viroid. *In Table 1, "(symptomless)*" means that some plant varieties or combinations of viroid species strains are symptomless. *A blank space in the "Symptoms of viroid-induced diseases in plants" column in Table 1 means that symptoms are present or the presence or absence of symptoms is unknown.

[0047] The type of viroid is not particularly limited as long as it is capable of infecting the plant species to be controlled. For example, in Table 1, one or more viroid species selected from the group of viroids shown in the fourth column from the left may be used as the active ingredient of a crown gall disease control agent for each plant species shown in the second column from the left.

[0048] Therefore, for example, the active ingredient of an agent for controlling crown gall disease in apples may be one or more viroids selected from the group consisting of apple dent fruit viroid (ADFVd), apple citrus fruit viroid (AFCVd), apple scar scar viroid (ASSVd), and hop stunt viroid (HpSVd). Among the viroid species shown in the third column from the left in Table 1, those marked "asymptomatic" or "(asymptomatic) *" in the rightmost column of Table 1 can be preferably used.

[0049] Viroids that may be used as active ingredients in agents for controlling crown gall disease in tomatoes, grapes, and chrysanthemums will be described in detail below.

[0050] <Viroids inoculated into tomatoes> The viroid used as an active ingredient in the agent for controlling crown gall disease in tomato (Solanum lycopersicum) may be, for example, a viroid species of the genus Pospiviroid, or may be one or more viroids selected from the group consisting of potato spindle tuber viroid (PSTVd), chrysanthemum stunt viroid (CSVd), and hop latent viroid (HpLVd).

[0051] The viroid used as an active ingredient of the agent for controlling crown gall disease in tomatoes may be one or more types of RNA selected from the group consisting of the following T1 to T12. These tomato viroids are also capable of infecting all Solanaceae plants, and are therefore expected to be useful as active ingredients in agents for controlling crown gall disease in all Solanaceae plants. (T1) RNA having the base sequence shown in SEQ ID NO: 1. (T2) RNA having a base sequence in which one or more bases have been deleted, substituted, added or inserted in a region other than the two regions of the base sequence shown in SEQ ID NO: 1, namely the region consisting of the base sequence shown in SEQ ID NO: 2 and the region consisting of the base sequence shown in SEQ ID NO: 3. (T3) RNA having a base sequence having 85% or more sequence identity with the base sequence shown in SEQ ID NO: 1, and including a region consisting of the base sequence shown in SEQ ID NO: 2 and a region consisting of the base sequence shown in SEQ ID NO: 3. (T4) RNA having the base sequence shown in SEQ ID NO: 4. (T5) RNA having a base sequence in which one or more bases have been deleted, substituted, added or inserted in a region other than the two regions of the base sequence shown in SEQ ID NO: 4, namely the region consisting of the base sequence shown in SEQ ID NO: 5 and the region consisting of the base sequence shown in SEQ ID NO: 6. (T6) RNA having a base sequence having 85% or more sequence identity with the base sequence shown in SEQ ID NO: 4, and including a region consisting of the base sequence shown in SEQ ID NO: 2 and a region consisting of the base sequence shown in SEQ ID NO: 3. (T7) RNA having the base sequence shown in SEQ ID NO: 7. (T8) RNA having a base sequence in which one or more bases have been deleted, substituted, added or inserted in a region other than the two regions consisting of the base sequence shown in SEQ ID NO: 7, namely the region consisting of the base sequence shown in SEQ ID NO: 8 and the region consisting of the base sequence shown in SEQ ID NO: 9. (T9) A base sequence having 85% or more sequence identity with the base sequence shown in SEQ ID NO: 7, comprising a region consisting of the base sequence shown in SEQ ID NO: 8 and a region consisting of the base sequence shown in SEQ ID NO: 9. (T10) RNA having the base sequence shown in SEQ ID NO: 10. (T11) RNA having a base sequence in which one or more bases have been deleted, substituted, added or inserted in a region other than the two regions consisting of the base sequence shown in SEQ ID NO: 10, namely the region consisting of the base sequence shown in SEQ ID NO: 11 and the region consisting of the base sequence shown in SEQ ID NO: 12. (T12) A base sequence having 85% or more sequence identity with the base sequence shown in SEQ ID NO: 10, comprising a region consisting of the base sequence shown in SEQ ID NO: 11 and a region consisting of the base sequence shown in SEQ ID NO: 12.

[0052] When a circular RNA is used as a viroid, for example, each RNA consisting of the base sequence shown in SEQ ID NO: 1, SEQ ID NO: 4, SEQ ID NO: 7, and SEQ ID NO: 10 has a nucleotide containing the base located at the 5' end and a nucleotide containing the base located at the 3' end linked together.

[0053] (Sequence Identity) Herein, the sequence identity of a target base sequence (for example, the base sequence of the T3 RNA) to a reference base sequence (for example, the base sequence shown in SEQ ID NO: 1) can be determined as follows: First, the reference base sequence and the target base sequence are aligned. Gaps are included in each base sequence to maximize sequence identity. Next, the number of matching bases between the reference base sequence and the target base sequence is calculated, and the sequence identity can be calculated according to the following formula (1): Sequence identity (%) = number of matched bases / total number of bases in the target sequence × 100 (1)

[0054] (Number of deleted, substituted, added, or inserted bases) As used herein, the term "a base sequence in which one or more bases have been deleted, substituted, added, or inserted" refers to a base sequence in which one or more and ten or less, preferably one or more and eight or less, more preferably one or more and five or less, and even more preferably one or more and three or less bases have been deleted, substituted, added, or inserted.

[0055] (T1 RNA) The nucleotide sequence shown in SEQ ID NO: 1 is a nucleotide sequence that has been made public as one of the nucleotide sequences of potato spindle tuber viroid (PSTVd) (GenBank accession number: LC523666.1, VP69-2 strain).

[0056] The region consisting of the nucleotide sequence shown in SEQ ID NO: 2 and the region consisting of the nucleotide sequence shown in SEQ ID NO: 3 are each the nucleotide sequences of central conserved regions that are highly conserved among species of the genus Pospiviroid, to which potato spindle tuber viroid belongs. Hereinafter, regions other than the central conserved region that are highly conserved among species of the same genus are also referred to as "peripheral regions."

[0057] There are more than 160 natural mutants of viroids with mutations in the peripheral region, including potato spindle tuber viroid alone, and there have been many test cases in which mutations were actually introduced into the peripheral region and the viroid was then infected with a host. Therefore, for each viroid species, as long as the base sequence of the central conserved region is conserved, even if there are mutations in the peripheral region, the viroid will have the ability to infect a host, in other words, the ability to replicate within a host. In other words, the central conserved region is a region that has the ability to infect a host (the ability to replicate within a host).

[0058] (T2 RNA) The above-mentioned T2 RNA includes an RNA having a base sequence shown in SEQ ID NO: 1, in which there is no mutation in the central conserved region consisting of the base sequence shown in SEQ ID NO: 2 and the central conserved region consisting of the base sequence shown in SEQ ID NO: 3, but there are mutations only in the peripheral regions.

[0059] (T3 RNA) The base sequence of the T3 RNA is a base sequence that preferably has 90% or more sequence identity, more preferably 95% or more sequence identity, with the base sequence shown in SEQ ID NO:1. The above-mentioned T3 RNA includes an RNA consisting of a base sequence shown in SEQ ID NO: 1, which has a central conserved region consisting of the base sequence shown in SEQ ID NO: 2 and a central conserved region consisting of the base sequence shown in SEQ ID NO: 3, with no mutations in the central conserved region and mutations only in the peripheral regions.

[0060] (T4 RNA) The nucleotide sequence shown in SEQ ID NO: 4 is another published nucleotide sequence of potato spindle tuber viroid (PSTVd) (GenBank accession number: LC523663, VP72-1 strain). The nucleotide sequence shown in SEQ ID NO: 4 contains a central conserved region consisting of the nucleotide sequence shown in SEQ ID NO: 5 and a central conserved region consisting of the nucleotide sequence shown in SEQ ID NO: 6.

[0061] (T5 RNA) The above T5 RNA includes an RNA having a base sequence shown in SEQ ID NO: 4, in which there is no mutation in the central conserved region consisting of the base sequence shown in SEQ ID NO: 5 and the central conserved region consisting of the base sequence shown in SEQ ID NO: 6, but there are mutations only in the peripheral regions.

[0062] (T6 RNA) The base sequence of the T6 RNA is a base sequence that preferably has 90% or more sequence identity, and more preferably 95% or more sequence identity, with the base sequence shown in SEQ ID NO:4. The above T6 RNA includes an RNA consisting of a base sequence shown in SEQ ID NO: 4, which has a central conserved region consisting of the base sequence shown in SEQ ID NO: 5 and a central conserved region consisting of the base sequence shown in SEQ ID NO: 6, with no mutations in the central conserved region and mutations only in the peripheral regions.

[0063] (T7 RNA) The nucleotide sequence shown in SEQ ID NO: 7 is a nucleotide sequence that has been published as one of the nucleotide sequences of chrysanthemum dwarf viroid (CSVd) (DDBJ accession number: X16408.1, CSVd R). The nucleotide sequence shown in SEQ ID NO: 7 contains a central conserved region consisting of the nucleotide sequence shown in SEQ ID NO: 8 and a central conserved region consisting of the nucleotide sequence shown in SEQ ID NO: 9.

[0064] (T8 RNA) The above T8 RNA includes an RNA consisting of a base sequence shown in SEQ ID NO: 7, which has no mutations in the central conserved region consisting of the base sequence shown in SEQ ID NO: 8 and the central conserved region consisting of the base sequence shown in SEQ ID NO: 9, but has mutations only in the peripheral regions.

[0065] (T9 RNA) The base sequence of the T9 RNA is a base sequence that preferably has 90% or more sequence identity, and more preferably 95% or more sequence identity, with the base sequence shown in SEQ ID NO:7. The above-mentioned T9 RNA includes an RNA consisting of a base sequence shown in SEQ ID NO: 7, which has a central conserved region consisting of the base sequence shown in SEQ ID NO: 8 and a central conserved region consisting of the base sequence shown in SEQ ID NO: 9, with no mutations in the central conserved region and mutations only in the peripheral regions.

[0066] (T10 RNA) The nucleotide sequence shown in SEQ ID NO: 10 is a nucleotide sequence that has been made public as one of the nucleotide sequences of hop latent viroid (HpLVd) (GenBank accession number: EF613183.1).

[0067] The region consisting of the base sequence shown in SEQ ID NO: 11 and the region consisting of the base sequence shown in SEQ ID NO: 8 are each the base sequences of central conserved regions that are highly conserved among species of the Cocadviroid genus, to which hop latent viroid belongs.

[0068] (T11 RNA) The above-mentioned T11 RNA includes an RNA having a base sequence of SEQ ID NO: 10 in which there is no mutation in the central conserved region consisting of the base sequence shown in SEQ ID NO: 11 and the central conserved region consisting of the base sequence shown in SEQ ID NO: 12, but there are mutations only in the peripheral regions.

[0069] (T12 RNA) The base sequence of the T12 RNA is a base sequence that preferably has 90% or more sequence identity, and more preferably 95% or more sequence identity, with the base sequence shown in SEQ ID NO:10. The above-mentioned T12 RNA includes an RNA having a base sequence of SEQ ID NO: 10 in which there is no mutation in the central conserved region consisting of the base sequence shown in SEQ ID NO: 11 and the central conserved region consisting of the base sequence shown in SEQ ID NO: 12, but there are mutations only in the peripheral regions.

[0070] <Viroids inoculated into grapes> The viroid used as an active ingredient of the agent for controlling crown gall disease in grapevine (scientific name: Vitis spp.) may be, for example, one or more viroids selected from the group consisting of hop dwarf viroid (HpSVd), grapevine yellow speckle viroid 1 (GYSVd-1), citrus exocortis viroid (CEVd), grapevine yellow speckle viroid 2 (GYSVd-2), and grapevine Australian viroid (AGVd).

[0071] The viroid used as an active ingredient of the agent for controlling crown gall disease in grapevine may be one or more types of RNA selected from the group consisting of G1 to G15 below. These viroids are also expected to be useful as active ingredients in agents for controlling crown gall disease in all Vitaceae plants. (G1) RNA having the base sequence shown in SEQ ID NO: 13. (G2) RNA having a base sequence in which one or more bases have been deleted, substituted, added or inserted in a region other than the two regions of the base sequence shown in SEQ ID NO: 13, namely, the region consisting of the base sequence shown in SEQ ID NO: 14 and the region consisting of the base sequence shown in SEQ ID NO: 15. (G3) A base sequence having 85% or more sequence identity with the base sequence shown in SEQ ID NO: 13, comprising a region consisting of the base sequence shown in SEQ ID NO: 14 and a region consisting of the base sequence shown in SEQ ID NO: 15. (G4) RNA having the base sequence shown in SEQ ID NO: 16. (G5) RNA having a base sequence in which one or more bases have been deleted, substituted, added or inserted in a region other than the two regions of the base sequence shown in SEQ ID NO: 16, namely, the region consisting of the base sequence shown in SEQ ID NO: 17 and the region consisting of the base sequence shown in SEQ ID NO: 18. (G6) A base sequence having 85% or more sequence identity with the base sequence shown in SEQ ID NO: 16, comprising a region consisting of the base sequence shown in SEQ ID NO: 17 and a region consisting of the base sequence shown in SEQ ID NO: 18. (G7) RNA having the base sequence shown in SEQ ID NO: 19. (G8) RNA having a base sequence in which one or more bases have been deleted, substituted, added or inserted in a region other than the two regions of the base sequence shown in SEQ ID NO: 19, namely, the region consisting of the base sequence shown in SEQ ID NO: 20 and the region consisting of the base sequence shown in SEQ ID NO: 21. (G9) A base sequence having 85% or more sequence identity with the base sequence shown in SEQ ID NO: 19, comprising a region consisting of the base sequence shown in SEQ ID NO: 20 and a region consisting of the base sequence shown in SEQ ID NO: 21. (G10) RNA having the base sequence shown in SEQ ID NO: 22. (G11) RNA having a base sequence in which one or more bases have been deleted, substituted, added or inserted in a region of the base sequence shown in SEQ ID NO: 22 other than the region consisting of the base sequence shown in SEQ ID NO: 23. (G12) An RNA having a base sequence having 85% or more sequence identity with the base sequence shown in SEQ ID NO: 22 and containing a region consisting of the base sequence shown in SEQ ID NO: 23. (G13) RNA having the base sequence shown in SEQ ID NO: 24. (G14) RNA having a base sequence in which one or more bases have been deleted, substituted, added or inserted in a region of the base sequence shown in SEQ ID NO: 24 other than the region consisting of the base sequence shown in SEQ ID NO: 25. (G15) An RNA having a base sequence having 85% or more sequence identity with the base sequence shown in SEQ ID NO: 24, and comprising a region consisting of the base sequence shown in SEQ ID NO: 25.

[0072] (G1 RNA) The nucleotide sequence shown in SEQ ID NO: 13 is a published nucleotide sequence of one of the nucleotide sequences of hop stunt viroid (HpSVd) (GenBank accession number: AB039265.1, hFK82 strain). The nucleotide sequence shown in SEQ ID NO: 13 includes the nucleotide sequence of a central conserved region consisting of the nucleotide sequence shown in SEQ ID NO: 14, which is highly conserved among species of the genus Hostuviroid, and the nucleotide sequence of a central conserved region consisting of the nucleotide sequence shown in SEQ ID NO: 15.

[0073] (G2 RNA) The G2 RNA includes an RNA having a base sequence of SEQ ID NO: 13 in which there is no mutation in the central conserved region consisting of the base sequence shown in SEQ ID NO: 14 and the central conserved region consisting of the base sequence shown in SEQ ID NO: 15, but there are mutations only in other peripheral regions.

[0074] (G3 RNA) The base sequence of the G3 RNA is a base sequence that preferably has 90% or more sequence identity, more preferably 95% or more sequence identity, with the base sequence shown in SEQ ID NO:13. The above G3 RNA includes an RNA having a base sequence of SEQ ID NO: 13 in which there is no mutation in the central conserved region consisting of the base sequence shown in SEQ ID NO: 14 and the central conserved region consisting of the base sequence shown in SEQ ID NO: 15, but there are mutations only in other peripheral regions.

[0075] (G4 RNA) The nucleotide sequence shown in SEQ ID NO: 16 is a published nucleotide sequence of Grapevine yellow spot viroid 1 (GYSVd-1) (GenBank accession number: X87906.1, variant II RNA sequence). The nucleotide sequence shown in SEQ ID NO: 16 contains the nucleotide sequence of a central conserved region consisting of the nucleotide sequence shown in SEQ ID NO: 17 and the nucleotide sequence of a central conserved region consisting of the nucleotide sequence shown in SEQ ID NO: 18. These central conserved regions are well conserved among species in the genus Apscaviroid.

[0076] (G5 RNA) The above G5 RNA includes an RNA having a base sequence of SEQ ID NO: 16 in which there is no mutation in the central conserved region consisting of the base sequence shown in SEQ ID NO: 17 and the central conserved region consisting of the base sequence shown in SEQ ID NO: 18, but there are mutations only in other peripheral regions.

[0077] (G6 RNA) The base sequence of the G6 RNA is a base sequence that preferably has 90% or more sequence identity, more preferably 95% or more sequence identity, with the base sequence shown in SEQ ID NO:16. The above G6 RNA includes an RNA having a base sequence of SEQ ID NO: 16 in which there is no mutation in the central conserved region consisting of the base sequence shown in SEQ ID NO: 17 and the central conserved region consisting of the base sequence shown in SEQ ID NO: 18, but there are mutations only in other peripheral regions.

[0078] (G7 RNA) The nucleotide sequence shown in SEQ ID NO: 19 is a published nucleotide sequence of one of the nucleotide sequences of Citrus exocortis viroid (CEVd) (GenBank accession number: Y00328.1). The nucleotide sequence shown in SEQ ID NO: 19 contains the nucleotide sequence of a central conserved region consisting of the nucleotide sequence shown in SEQ ID NO: 20 and the nucleotide sequence of a central conserved region consisting of the nucleotide sequence shown in SEQ ID NO: 21. These central conserved regions are well conserved among species of the genus Pospiviroid.

[0079] (G8 RNA) The G8 RNA includes an RNA having a base sequence shown in SEQ ID NO: 19 in which there is no mutation in the central conserved region consisting of the base sequence shown in SEQ ID NO: 20 and the central conserved region consisting of the base sequence shown in SEQ ID NO: 21, but there are mutations only in other peripheral regions.

[0080] (G9 RNA) The base sequence of the G9 RNA is a base sequence that preferably has 90% or more sequence identity, more preferably 95% or more sequence identity, with the base sequence shown in SEQ ID NO:19. The G9 RNA includes an RNA having a base sequence shown in SEQ ID NO: 19, in which there is no mutation in the central conserved region consisting of the base sequence shown in SEQ ID NO: 20 and the central conserved region consisting of the base sequence shown in SEQ ID NO: 21, but there are mutations only in other peripheral regions.

[0081] (G10 RNA) The nucleotide sequence shown in SEQ ID NO: 22 is a published nucleotide sequence of grapevine yellow speckle viroid 2 (GYSVd-2) (GenBank accession number: NC_003612.1). The nucleotide sequence shown in SEQ ID NO: 22 contains the nucleotide sequence of a central conserved region consisting of the nucleotide sequence shown in SEQ ID NO: 23. This central conserved region is well conserved among species in the genus Apscaviroid.

[0082] (G11 RNA) The above-mentioned G11 RNA includes an RNA consisting of a base sequence shown in SEQ ID NO: 22, which has no mutation in the central conserved region consisting of the base sequence shown in SEQ ID NO: 23, but has mutations only in other peripheral regions.

[0083] (G12 RNA) The base sequence of the RNA of G12 is a base sequence having preferably 90% or more sequence identity, more preferably 95% or more sequence identity, with the base sequence shown in SEQ ID NO:22. The above G12 RNA includes RNA consisting of the base sequence shown in SEQ ID NO: 22, which has no mutation in the central conserved region consisting of the base sequence shown in SEQ ID NO: 23, but has mutations only in other peripheral regions.

[0084] (G13 RNA) The nucleotide sequence shown in SEQ ID NO: 24 is a published nucleotide sequence of Grapevine Australian viroid (AGVd) (GenBank accession number: DQ362908.2). The nucleotide sequence shown in SEQ ID NO: 24 contains the nucleotide sequence of a central conserved region consisting of the nucleotide sequence shown in SEQ ID NO: 25. This central conserved region is well conserved among species of the genus Apscaviroid.

[0085] (G14 RNA) The above G14 RNA includes RNA consisting of the base sequence shown in SEQ ID NO: 24, which has no mutation in the central conserved region consisting of the base sequence shown in SEQ ID NO: 25, but has mutations only in other peripheral regions.

[0086] (G15 RNA) The base sequence of the G15 RNA is a base sequence that preferably has 90% or more sequence identity, more preferably 95% or more sequence identity, with the base sequence shown in SEQ ID NO:24. The above G15 RNA includes RNA consisting of a base sequence shown in SEQ ID NO: 24, which has no mutation in the central conserved region consisting of the base sequence shown in SEQ ID NO: 25, but has mutations only in other peripheral regions.

[0087] <Viroids inoculated into chrysanthemums> The viroid used as an active ingredient in the agent for controlling crown gall disease in chrysanthemum (scientific name: Chrysanthemum morifolium) may be, for example, one or more viroids selected from the group consisting of potato spindle tuber viroid (PSTVd), chrysanthemum stunt viroid (CSVd), and hop latent viroid (HpLVd). Furthermore, the viroid used as an active ingredient of the agent for controlling crown gall disease in chrysanthemum may be, for example, one or more types of RNA selected from the group consisting of the above-mentioned T1 to T12.

[0088] Furthermore, the viroid used as the active ingredient of the crown gall disease control agent for plants of the Asteraceae family in general may be one or more RNAs selected from the group consisting of the above-mentioned T1 to T9, or one or more viroids selected from the group consisting of potato spindle tuber viroid (PSTVd) and chrysanthemum dwarf viroid (CSVd).

[0089] The types of viroids used as active ingredients to inoculate tomatoes, grapes, and chrysanthemums have been described in detail above. However, as mentioned above, the type of viroid is not particularly limited as long as it can infect the target plant species to be controlled (in other words, it can grow inside the plants to be controlled from crown gall disease).

[0090] Therefore, for example, the potato spindle tuber viroid (PSTVd) used in the examples described below can infect plants of the Asteraceae family, Solanaceae family, Amaranthaceae family, Sapindaceae family, Boraginaceae family, Campanulaceae family, Convolvulaceae family, Dipsacaceae family, Valerianaceae family, Scrophulariaceae family, and Caryophyllaceae family. Therefore, potato spindle tuber viroid can be used as an active ingredient of an agent for controlling crown gall disease in one or more plants selected from the group consisting of plants of these families.

[0091] Furthermore, the chrysanthemum dwarf viroid (CSVd) used in the Examples described below can infect plants of the Asteraceae family and the Solanaceae family. Therefore, the chrysanthemum dwarf viroid can be used as an active ingredient of an agent for controlling crown gall disease in one or more plants selected from the group consisting of plants of the Asteraceae family and plants of the Solanaceae family.

[0092] Hop stunt viroid (HpSVd) can also infect plants of the mulberry family, cucurbit family, solanaceae family, asteraceae family, rosaceae family, vitiaceae family, citrus family, and cannabis family. Therefore, the hop stunt viroid can be used as an active ingredient of a crown gall disease control agent for one or more plants selected from the group consisting of plants of the family Moraceae, Cucurbitaceae, Solanaceae, Asteraceae, Rosaceae, Vitaceae, and Cannabaceae.

[0093] Hop latent viroid (HpLVd) can also infect plants of the Solanaceae family, Asteraceae family, and Cannabaceae family. Therefore, hop latent viroid can be used as an active ingredient of an agent for controlling crown gall disease in one or more plants selected from the group consisting of plants of the Solanaceae family, plants of the Asteraceae family, and plants of the Cannabaceae family.

[0094] Citrus exocortis viroid (CEVd) can also infect plants of the Solanaceae family, Vitaceae family, Rutaceae family, and Cannabaceae family. Therefore, citrus exocortis viroid can be used as an active ingredient of an agent for controlling crown gall disease in one or more plants selected from the group consisting of Solanaceae plants, Vitaceae plants, Rutaceae plants, and Cannabaceae plants.

[0095] Furthermore, the viroid contained in the crown gall disease control agent may be one or more viroids selected from the group consisting of viroids belonging to the genus Absunviroid, viroids belonging to the genus Pelamoviroid, viroids belonging to the genus Elaviroid, viroids belonging to the genus Pospiviroid, viroids belonging to the genus Hostuviroid, viroids belonging to the genus Cocadviroid, viroids belonging to the genus Apscaviroid, and viroids belonging to the genus Coleviroid.

[0096] The viroid used as the active ingredient of the agent for controlling crown gall disease is preferably one that has the ability to grow (in other words, the ability to replicate, replication activity) in the host plant.

[0097] Regardless of the type of plant, the length of the RNA of each viroid to be inoculated into the plant is not particularly limited, but may be, for example, 390 nucleotides or less, 380 nucleotides or less, 370 nucleotides or less, or 360 nucleotides or less.

[0098] <Components other than viroids> The crown gall disease control agent of this embodiment may contain, in addition to the viroid described above, other components as long as they do not inhibit the plant's infectivity. Components other than the viroid include, for example, solvents such as water, as well as agriculturally and horticulturally acceptable carriers, such as solid carriers, liquid carriers, and gaseous carriers, in accordance with conventional methods for agricultural and horticultural disease control agents, but are not limited to these. The crown gall disease control agent may, for example, be an extract from a plant in which a viroid has proliferated.

[0099] The form of the agent for controlling crown gall disease is not particularly limited, and may be, for example, a liquid, a powder, a granule, a tablet, or the like.

[0100] <How to obtain Viroids> The method for obtaining each of the above viroids is not particularly limited, but examples include isolating them from natural plant species that serve as hosts for each viroid, or obtaining them as a homogenate from infected leaves, as described in detail below. The viroid isolated from a plant species or obtained as a homogenate may be inoculated into a host plant species, allowed to grow within the plant, and then separated and inoculated into a plant to be controlled. This allows the amount of viroid to be increased. Alternatively, each of the above viroid species may be inoculated into a plant (other than the individual plant to be controlled) and cultivated, and those that have only a minor effect on the host plant may be selected, and then inoculated into the individual plant to be controlled as a control agent (or its active ingredient).

[0101] The method for isolating viroids from natural plant species is not particularly limited, but an example thereof is the method disclosed in JP 2014-131498 A.

[0102] On the other hand, viroids can also be artificially synthesized by known methods, etc. For example, the following document describes that an infectious viroid can be obtained by synthesizing a cDNA of a tandem dimeric viroid sequence (viroid dimeric cDNA) from a full-length viroid monomer, adding a T7 promoter sequence to the 5' end of the cDNA, and then transcribing the cDNA into RNA using the cDNA as a template. J, Marquez-Molins et al., Highly efficient construction of infectious viroid-derived clones. Plant Methods 15, 87, 2019.

[0103] <Storage method> There are no particular limitations on the method for storing the viroid to be inoculated into the plant, but for example, it may be stored together with the host plant in an infected state (cultivating the plant).

[0104] The method of inoculating the crown gall disease control agent of this embodiment is not particularly limited, and examples thereof include the inoculation method in the embodiment of the control method described in detail below.

[0105] [Method for controlling crown gall disease in plants] A method for controlling crown gall disease in plants according to a preferred embodiment of the present invention includes a step of inoculating a plant with the above-mentioned crown gall disease control agent (inoculation step). The plant to be inoculated with the crown gall disease control agent is as described above.

[0106] <Inoculation process> (Inoculation method) The above-mentioned method for inoculating a viroid is not particularly limited as long as it is a method that can infect plants with a viroid, but examples include grinding the leaves of a plant already infected with a viroid in water or a buffer solution to obtain a homogenate (an example of a control agent), then spraying carborundum on the leaves, stems, etc. of the plant to be inoculated, and rubbing the homogenate on the leaves, stems, etc. of the plant to be inoculated. Another example of an inoculation method includes rubbing a cotton swab that has been rubbed on the leaves of another plant already infected with a viroid to impregnate the cotton swab with a control agent, which is a liquid containing the viroid, on the leaves, stems, etc. of a plant from which crown gall fungus is to be controlled. When applying the viroid-containing liquid to the cotton swab and when rubbing the liquid onto the leaves, stems, etc. of the plant to be controlled from the cotton swab, it is preferable to scrape the surfaces of the leaves, stems, etc. in advance using an abrasive, etc. Celite, for example, can be used as an abrasive. Alternatively, a solution containing the viroid may be injected into the stems, roots, etc. of the plant to be controlled using a syringe or the like.

[0107] (inoculation site) The part of the plant to which the control agent of the embodiment is inoculated is not particularly limited, and may be, for example, the stem, the root, or the leaf. When the control agent of the embodiment is inoculated into a plant that has already developed crown gall disease, it may be inoculated into the part where the gall has formed (the stem or the root).

[0108] (Vaccination period) The timing of inoculating plants with the above-mentioned viroids is not particularly limited, but it is preferably before the plant is infected with the crown gall fungus (i.e., before the onset of crown gall disease), and more preferably at the seedling stage. Even after inoculation with the viroid, the plant may be inoculated with the viroid periodically or when the viroid in the plant has disappeared or decreased. Whether or not the viroid in the plant body has disappeared or decreased can be confirmed, for example, by extracting nucleic acid from the plant and performing Northern hybridization, RT-PCR, or LAMP.

[0109] (Inoculation amount) The amount of the control agent of the embodiment to be inoculated into a plant is not particularly limited, but it is preferable that the amount of viroid, which is RNA, be 100 ng or more.

[0110] According to the method for controlling crown gall disease in plants of this embodiment, crown gall disease can be prevented, suppressed, or ameliorated by inoculating a target plant with an infective viroid species.

[0111] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the invention described in the claims, and it goes without saying that these modifications are also included within the scope of the present invention. [Example]

[0112] The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

[0113] FIG. 1 is a schematic diagram of an experimental example. [Experimental Example 1] In this experiment, the stems of cherry tomatoes (Senka, registered trademark) were inoculated with chrysanthemum stunt viroid (CSVd). Specifically, 0.1 g of chrysanthemum or tomato leaves infected with chrysanthemum stunt viroid was ground in 2 mL of phosphate buffer or 2 mL of water. Carborundum was then sprayed onto the leaves of the cherry tomatoes to be inoculated, and the ground liquid from the infected leaves was rubbed onto the carborundum for inoculation.

[0114] The inoculated chrysanthemum dwarf viroid is a single-stranded circular RNA consisting of the base sequence set forth in SEQ ID NO: 7. In addition, as a control, seedlings that were not inoculated with the viroid were also prepared.

[0115] Thirty days after inoculation with the viroid, the stems of seedlings propagated by cuttings from individuals confirmed to be infected with the viroid by RT-PCR (no infection was confirmed in the control area) were infected by piercing the stems with a needle (previously sterilized) containing the crown gall pathogen Allorhizobium vitis (synonyms: Rhizobium vitis, Agrobacterium vitis, Agrobacterium tumefaciens biovar 3), VAT20-3 strain) collected from grapevines at 10 sites.

[0116] Five weeks after inoculation with the crown gall fungus, the presence or absence of cankers, the number of cankers, and the diameter of the cankers were measured for the seedlings trained from the viroid-infected and uninfected seedlings (both of which were infected with the crown gall fungus).

[0117] Figure 2 is an image showing the stem of a cherry tomato inoculated with crown gall fungus.

[0118] Table 2 below shows the number of seedlings that developed gall 1 and the number of seedlings that did not develop gall 1 for seedlings inoculated with chrysanthemum dwarf viroid and crown gall fungus (CSVd tomatoes) and seedlings inoculated with crown gall fungus but not with chrysanthemum dwarf viroid (healthy tomatoes).

[0119] [Table 2]

[0120] As shown in Figure 2 and Table 2, the number of cherry tomato seedlings that had developed canker 1 was significantly lower in the seedlings that had been inoculated with chrysanthemum dwarf viroid in advance than in the seedlings that had not been inoculated with chrysanthemum dwarf viroid. The Fisher's exact test was used to test for significance, with p<2.2 × 10 -16 It was.

[0121] Table 3 below shows the percentage of seedlings with Canker 1 and the risk of canker formation for the CSVd tomatoes and the healthy tomatoes. The risk of canker formation is calculated by dividing the percentage of seedlings with Canker 1 in the CSVd tomatoes by the percentage of seedlings with Canker 1 in the healthy tomatoes.

[0122] [Table 3]

[0123] As shown in Table 3, the risk of cancer formation in cherry tomatoes previously inoculated with chrysanthemum stunt viroid was 0.1719 times (control value 82.8) compared to tomatoes of the same variety not inoculated with chrysanthemum stunt viroid.

[0124] FIG. 3 is a graph showing the diameter distribution and average diameter of the carcinoma 1 formed in the CSVd tomato (cherry tomato) and the diameter distribution and average diameter of the carcinoma 1 formed in the healthy tomato (cherry tomato).

[0125] As shown in FIG. 3, it was confirmed that the carcinoma 1 formed in the CSVd tomatoes was, on average, significantly smaller than the carcinoma 1 formed in the healthy tomatoes.

[0126] These results demonstrate that the formation of canker 1 can be effectively suppressed by inoculating plants with chrysanthemum stunt viroid in advance. In addition, the control effect was confirmed against the crown gall fungus collected from grapes, suggesting that crown gall disease can also be controlled in grapes by inoculating them with chrysanthemum stunt viroid.

[0127] [Experimental Example 2] In this experiment, the same experiment as in Experimental Example 1 was carried out using Rutgers, a variety of tomato, instead of cherry tomatoes.

[0128] Figure 4 is an image showing a stem of Rutgers inoculated with crown gall fungus.

[0129] Table 4 below shows the number of seedlings that developed tumor 1 and the number of seedlings that did not develop tumor 1 for seedlings (CSVd tomato) inoculated with chrysanthemum stunt viroid and the crown gall fungus (Allorhizobium vitis, VAT20-3 strain) collected from grapevine, and for seedlings (healthy tomato) inoculated with the above-mentioned crown gall fungus without inoculation with chrysanthemum stunt viroid. [Table 4]

[0130] As shown in Figure 4 and Table 4, the number of seedlings with canker 1 formed in Rutgers seedlings that had been inoculated with chrysanthemum stunt viroid was significantly lower than in seedlings that had not been inoculated with chrysanthemum stunt viroid. The Fisher's exact test was used to test for significance, with p<2.704×10 -14 It was.

[0131] Table 5 below shows the percentage of seedlings that developed canker 1 and the risk of canker formation for the CSVd tomatoes (Rutgers) and the healthy tomatoes (Rutgers). The risk of canker formation is calculated by dividing the percentage of seedlings that developed canker 1 in the CSVd tomatoes (Rutgers) by the percentage of seedlings that developed canker 1 in the healthy tomatoes (Rutgers).

[0132] [Table 5]

[0133] As shown in Table 5, the risk of canker formation in Rutgers tomatoes that had been inoculated with Chrysanthemum Stunt Viroid was 0.3036 times higher than that of tomatoes of the same variety that had not been inoculated with Chrysanthemum Stunt Viroid.

[0134] FIG. 5 is a graph showing the diameter distribution and average diameter of the carcinoma 1 formed in the CSVd tomato (Rutgers) and the diameter distribution and average diameter of the carcinoma 1 formed in the healthy tomato (Rutgers).

[0135] As shown in FIG. 5, it was confirmed that the carcinoma 1 formed in the CSVd tomatoes (Rutgers) was significantly smaller on average than the carcinoma 1 formed in the healthy tomatoes (Rutgers). These results demonstrated that inoculation with chrysanthemum stunt viroid suppresses the size of gall tumors, even if they do form, and reduces the symptoms of crown gall disease in plants.

[0136] These results demonstrate that the formation of canker 1 can be effectively suppressed by inoculating chrysanthemum stunt viroid in advance, regardless of plant variety.

[0137] [Experimental Example 3] In this experiment, Micro-Tom, a variety of tomato, was used instead of the cherry tomato, and potato spindle tuber viroid (PSTVd) was used instead of the chrysanthemum stunt viroid, but the experiment was conducted in the same manner as in Experimental Example 1. Two test plots were prepared using VP69-2 and VP72-1 as potato spindle tuber viroids.

[0138] VP69-2 is a circular RNA viroid consisting of the base sequence shown in SEQ ID NO:1, and VP72-1 is a circular RNA viroid consisting of the base sequence shown in SEQ ID NO:4.

[0139] Table 6 below shows the number of seedlings that developed galls and the number of seedlings that did not develop galls for seedlings (PSTVd(VP69-2) tomatoes) inoculated with the potato spindle tuber viroid VP69-2 strain and the crown gall fungus (Allorhizobium vitis, VAT20-3 strain) collected from grapes, and for seedlings (healthy tomatoes) inoculated with the above-mentioned crown gall fungus without inoculating with potato spindle tuber viroid.

[0140] [Table 6]

[0141] As shown in Table 6, the number of PSTVd(VP69-2) tomato seedlings that had been inoculated with the potato spindle tuber viroid VP69-2 strain was significantly lower than that of healthy tomato seedlings that had not been inoculated with potato spindle tuber viroid. The Fisher's exact test was used to test for significance, with p<2.2 × 10 -16 It was.

[0142] The percentage of seedlings with cankers and the risk of canker formation for the PSTVd(VP69-2) tomatoes and the healthy tomatoes are shown in Table 7. The risk of canker formation is calculated by dividing the percentage of seedlings with cankers in the PSTVd(VP69-2) tomatoes by the percentage of seedlings with cankers in the healthy tomatoes.

[0143] [Table 7]

[0144] As shown in Table 7, the risk of canker formation in PSTVd(VP69-2) tomatoes previously inoculated with potato spindle tuber viroid VP69-2 was 0.2703 times higher than in healthy tomatoes not inoculated with potato spindle tuber viroid. This confirms that inoculation with potato spindle tuber viroid VP69-2 can prevent canker formation in plants.

[0145] Table 8 below shows the number of seedlings that developed galls and the number of seedlings that did not develop galls for seedlings (PSTVd(VP72-1) tomatoes) inoculated with the potato spindle tuber viroid VP72-1 strain and the crown gall pathogen (Allorhizobium vitis, VAT20-3 strain) collected from grapes, and for seedlings (healthy tomatoes) inoculated with the above-mentioned crown gall pathogen without inoculating with potato spindle tuber viroid.

[0146] [Table 8]

[0147] As shown in Table 8, the number of PSTVd(VP72-1) tomato seedlings that had been inoculated with the potato spindle tuber viroid VP72-1 strain in advance was significantly lower than that of healthy tomato seedlings that had not been inoculated with potato spindle tuber viroid. The Fisher's exact test was used to test for significance, with p<2.2×10 -16 It was.

[0148] The percentage of seedlings with cankers and the risk of canker formation for the PSTVd(VP72-1) tomatoes and the healthy tomatoes are shown in Table 9. The risk of canker formation is calculated by dividing the percentage of seedlings with cankers in the PSTVd(VP72-1) tomatoes by the percentage of seedlings with cankers in the healthy tomatoes.

[0149] [Table 9]

[0150] As shown in Table 9, the risk of canker formation in PSTVd(VP72-1) tomatoes previously inoculated with potato spindle tuber viroid VP72-1 strain was 0.0090 times higher than in healthy tomatoes not inoculated with potato spindle tuber viroid. This confirms that inoculation with potato spindle tuber viroid VP72-1 strain can also prevent canker formation in plants.

[0151] Figure 6 is a graph showing the diameter distribution and mean diameter of carcinomas formed in PSTVd(VP69-2) tomatoes, PSTVd(VP72-1) tomatoes, and healthy tomatoes.

[0152] As shown in FIG. 6, it can be seen that the carcinomas formed in the PSTVd(VP69-2) tomatoes and the PSTVd(VP72-1) tomatoes were significantly smaller than the carcinomas formed in the healthy tomatoes (Rutgers).

[0153] These results revealed that inoculation with potato rootstock viroid suppresses the size of gall tumors, even if they do form, and reduces the symptoms of crown gall disease in plants. In addition, it was revealed that the potato spindle tuber viroid strain VP72-1 has a much higher anti-cancer effect than the strain VP69-2.

[0154] The results of the above experiments demonstrated that any viroid that can infect plants, regardless of the type, is effective in controlling crown gall disease.

[0155] [Experimental Example 4] In this experiment, chrysanthemum (Dendron daisy) stems were first inoculated with chrysanthemum dwarf viroid (CSVd; see SEQ ID NO: 7 for the base sequence; single-stranded circular RNA). Thirty days after inoculation, the stems of seedlings confirmed to be infected with the viroid by RT-PCR were infected with the crown gall fungus by inoculation at 10 sites using a pre-sterilized needle. The viroid inoculation was carried out in the same manner as in Experimental Example 1 above. Five weeks after inoculation with the crown gall fungus, the presence and diameter of galls were confirmed.

[0156] Two test plots were prepared using the crown gall fungus, the VAT03-9 strain of Allorhizobium vitis and the VAT21-19 strain. A separate control plot was also prepared, in which the plants were inoculated with the crown gall fungus alone, without the chrysanthemum stunt viroid.

[0157] Table 10 below shows the number of seedlings that developed galls and the number of seedlings that did not develop galls for the test plots inoculated with chrysanthemum dwarf viroid and the VAT03-9 strain of Allorhizobium vitis, the causative agent of crown gall disease (CSVd-infected chrysanthemums), and the test plots inoculated with the VAT03-9 strain of Allorhizobium vitis without inoculation with chrysanthemum dwarf viroid (CSVd-uninfected chrysanthemums).

[0158] [Table 10]

[0159] Table 11 below shows the number of seedlings that developed galls and the number of seedlings that did not develop galls for the test plots inoculated with chrysanthemum dwarf viroid and the VAT21-19 strain of Allorhizobium vitis, the causative agent of crown gall disease (CSVd-infected chrysanthemums), and the test plots inoculated with the VAT21-19 strain of Allorhizobium vitis without inoculation with chrysanthemum dwarf viroid (CSVd-uninfected chrysanthemums).

[0160] [Table 11]

[0161] As shown in Tables 10 and 11, in the test plots inoculated with chrysanthemum stunt viroid in advance, the formation of canker tumors was remarkably and significantly suppressed. Fisher's exact test was used to test for significance, with p<2.2×10 -16 It was.

[0162] Figure 7 is a graph showing the diameter distribution and average diameter of cankers formed on CSVd-infected chrysanthemums in the test plot inoculated with the VAT03-9 strain of Allorhizobium vitis, and the diameter distribution and average diameter of cankers formed on CSVd-uninfected chrysanthemums in the test plot inoculated with the VAT21-19 strain of Allorhizobium vitis. Figure 8 is a graph showing the diameter distribution and average diameter of cankers formed on CSVd-infected chrysanthemums in the test plot inoculated with the VAT21-19 strain of Allorhizobium vitis, and the diameter distribution and average diameter of cankers formed on CSVd-uninfected chrysanthemums in the test plot inoculated with the VAT21-19 strain of Allorhizobium vitis.

[0163] As shown in Figures 7 and 8, in both the test plots inoculated with the VAT03-9 strain of Allorhizobium vitis and the test plots inoculated with the VAT21-19 strain, the average diameter of the cankers formed in CSVd-infected chrysanthemums was smaller than that of the cankers formed in non-CSVd-infected chrysanthemums. In particular, in the test plot inoculated with the VAT03-9 strain of Allorhizobium vitis, the size of the cankers was significantly suppressed in CSVd-infected chrysanthemums.

[0164] These results demonstrate that the formation of crown gall tumors can be effectively suppressed by inoculating chrysanthemums with chrysanthemum stunt viroid in advance, regardless of the strain of the crown gall pathogen.

[0165] In addition, tomatoes, which were found to have an inhibitory effect on cancer formation in Experimental Examples 1 to 3, are plants of the Solanaceae family, while chrysanthemums are plants of the Asteraceae family, and these are phylogenetically distant plants. Therefore, it was strongly suggested that the inhibitory effect of viroids on cancer formation may be exerted regardless of the type of plant, as long as the viroid infects the plant. [Industrial Applicability]

[0166] According to the present invention, by inoculating a plant with a viroid, crown gall disease in the plant can be controlled, and therefore the present invention is industrially applicable. [Explanation of symbols]

[0167] 1…Carcinoma

Claims

1. A plant crown gall disease control agent containing a viroid as an active ingredient.

2. 2. The agent for controlling crown gall disease in plants according to claim 1, wherein the viroid has an ability to infect a target plant against which crown gall disease is to be controlled.

3. 3. The agent for controlling crown gall disease in plants according to claim 2, wherein the viroid is a species that is asymptomatic in plants.

4. The plant crown gall disease control agent according to claim 2, wherein the plant is a fruit tree, a flowering plant, or a vegetable.

5. The plant crown gall disease control agent according to claim 4, wherein the plant is a chrysanthemum.

6. The plant crown gall disease control agent according to claim 5, wherein the plant is a Solanaceae plant.

7. The agent for controlling crown gall disease in plants according to claim 6, wherein the plant is a tomato.

8. The plant crown gall disease control agent according to claim 7, wherein the viroid is one or more RNAs selected from the group consisting of T1 to T12 below. (T1) RNA having the base sequence shown in SEQ ID NO:

1. (T2) RNA having a base sequence in which one or more bases have been deleted, substituted, added or inserted in a region other than the two regions of the base sequence shown in SEQ ID NO: 1, namely, the region consisting of the base sequence shown in SEQ ID NO: 2 and the region consisting of the base sequence shown in SEQ ID NO:

3. (T3) A base sequence having 85% or more sequence identity with the base sequence shown in SEQ ID NO: 1, comprising a region consisting of the base sequence shown in SEQ ID NO: 2 and a region consisting of the base sequence shown in SEQ ID NO:

3. (T4) RNA having the base sequence shown in SEQ ID NO:

4. (T5) RNA having a base sequence in which one or more bases have been deleted, substituted, added or inserted in a region other than the two regions of the base sequence shown in SEQ ID NO: 4, namely, the region consisting of the base sequence shown in SEQ ID NO: 5 and the region consisting of the base sequence shown in SEQ ID NO:

6. (T6) A base sequence having 85% or more sequence identity with the base sequence shown in SEQ ID NO: 4, comprising a region consisting of the base sequence shown in SEQ ID NO: 2 and a region consisting of the base sequence shown in SEQ ID NO:

3. (T7) RNA having the base sequence shown in SEQ ID NO:

7. (T8) RNA having a base sequence in which one or more bases have been deleted, substituted, added or inserted in a region other than the two regions of the base sequence shown in SEQ ID NO: 7, namely, the region consisting of the base sequence shown in SEQ ID NO: 8 and the region consisting of the base sequence shown in SEQ ID NO:

9. (T9) A base sequence having 85% or more sequence identity with the base sequence shown in SEQ ID NO: 7, comprising a region consisting of the base sequence shown in SEQ ID NO: 8 and a region consisting of the base sequence shown in SEQ ID NO:

9. (T10) RNA having the base sequence shown in SEQ ID NO:

10. (T11) RNA having a base sequence in which one or more bases have been deleted, substituted, added or inserted in a region other than the two regions of the base sequence shown in SEQ ID NO: 10, namely, the region consisting of the base sequence shown in SEQ ID NO: 11 and the region consisting of the base sequence shown in SEQ ID NO:

12. (T12) A base sequence having 85% or more sequence identity with the base sequence shown in SEQ ID NO: 10, comprising a region consisting of the base sequence shown in SEQ ID NO: 11 and a region consisting of the base sequence shown in SEQ ID NO:

12.

9. 8. The plant crown gall disease control agent according to claim 7, wherein the viroid is one or more viroids selected from the group consisting of potato spindle tuber viroid (PSTVd), chrysanthemum dwarf viroid (CSVd), and hop latent viroid (HpLVd).

10. 5. The plant crown gall disease control agent according to claim 4, wherein the viroid is one or more RNAs selected from the group consisting of G1 to G15 below, and the plant is a Vitaceae plant. (G1) RNA having the base sequence shown in SEQ ID NO:

13. (G2) RNA having a base sequence in which one or more bases have been deleted, substituted, added or inserted in a region other than the two regions of the base sequence shown in SEQ ID NO: 13, namely, the region consisting of the base sequence shown in SEQ ID NO: 14 and the region consisting of the base sequence shown in SEQ ID NO:

15. (G3) A base sequence having 85% or more sequence identity with the base sequence shown in SEQ ID NO: 13, comprising a region consisting of the base sequence shown in SEQ ID NO: 14 and a region consisting of the base sequence shown in SEQ ID NO:

15. (G4) RNA having the base sequence shown in SEQ ID NO:

16. (G5) RNA having a base sequence in which one or more bases have been deleted, substituted, added or inserted in a region other than the two regions of the base sequence shown in SEQ ID NO: 16, namely, the region consisting of the base sequence shown in SEQ ID NO: 17 and the region consisting of the base sequence shown in SEQ ID NO:

18. (G6) A base sequence having 85% or more sequence identity with the base sequence shown in SEQ ID NO: 16, comprising a region consisting of the base sequence shown in SEQ ID NO: 17 and a region consisting of the base sequence shown in SEQ ID NO:

18. (G7) RNA having the base sequence shown in SEQ ID NO:

19. (G8) RNA having a base sequence in which one or more bases have been deleted, substituted, added or inserted in a region other than the two regions of the base sequence shown in SEQ ID NO: 19, namely, the region consisting of the base sequence shown in SEQ ID NO: 20 and the region consisting of the base sequence shown in SEQ ID NO:

21. (G9) A base sequence having 85% or more sequence identity with the base sequence shown in SEQ ID NO: 19, comprising a region consisting of the base sequence shown in SEQ ID NO: 20 and a region consisting of the base sequence shown in SEQ ID NO:

21. (G10) RNA having the base sequence shown in SEQ ID NO:

22. (G11) RNA having a base sequence in which one or more bases have been deleted, substituted, added or inserted in a region of the base sequence shown in SEQ ID NO: 22 other than the region consisting of the base sequence shown in SEQ ID NO:

23. (G12) An RNA having a base sequence having 85% or more sequence identity with the base sequence shown in SEQ ID NO: 22, and comprising a region consisting of the base sequence shown in SEQ ID NO:

23. (G13) RNA having the base sequence shown in SEQ ID NO:

24. (G14) RNA having a base sequence in which one or more bases have been deleted, substituted, added or inserted in a region of the base sequence shown in SEQ ID NO: 24 other than the region consisting of the base sequence shown in SEQ ID NO:

25. (G15) An RNA having a base sequence having 85% or more sequence identity with the base sequence shown in SEQ ID NO: 24, and comprising a region consisting of the base sequence shown in SEQ ID NO:

25.

11. the viroid is one or more viroids selected from the group consisting of hop dwarf viroid (HpSVd), grapevine yellow speckle viroid 1 (GYSVd-1), citrus exocortis viroid (CEVd), grapevine yellow speckle viroid 2 (GYSVd-2), and grapevine Australian viroid (AGVd); The agent for controlling crown gall disease in plants according to claim 4, wherein the plant is a Vitaceae plant.

12. The viroid is one or more RNAs selected from the group consisting of T1 to T9 below, The agent for controlling crown gall disease in plants according to claim 4, wherein the plant is a plant of the Asteraceae family. (T1) RNA having the base sequence shown in SEQ ID NO:

1. (T2) RNA having a base sequence in which one or more bases have been deleted, substituted, added or inserted in a region other than the two regions of the base sequence shown in SEQ ID NO: 1, namely, the region consisting of the base sequence shown in SEQ ID NO: 2 and the region consisting of the base sequence shown in SEQ ID NO:

3. (T3) A base sequence having 85% or more sequence identity with the base sequence shown in SEQ ID NO: 1, comprising a region consisting of the base sequence shown in SEQ ID NO: 2 and a region consisting of the base sequence shown in SEQ ID NO:

3. (T4) RNA having the base sequence shown in SEQ ID NO:

4. (T5) RNA having a base sequence in which one or more bases have been deleted, substituted, added or inserted in a region other than the two regions of the base sequence shown in SEQ ID NO: 4, namely, the region consisting of the base sequence shown in SEQ ID NO: 5 and the region consisting of the base sequence shown in SEQ ID NO:

6. (T6) A base sequence having 85% or more sequence identity with the base sequence shown in SEQ ID NO: 4, comprising a region consisting of the base sequence shown in SEQ ID NO: 5 and a region consisting of the base sequence shown in SEQ ID NO:

6. (T7) RNA having the base sequence shown in SEQ ID NO:

7. (T8) RNA having a base sequence in which one or more bases have been deleted, substituted, added or inserted in a region other than the two regions of the base sequence shown in SEQ ID NO: 7, namely, the region consisting of the base sequence shown in SEQ ID NO: 8 and the region consisting of the base sequence shown in SEQ ID NO:

9. (T9) A base sequence having 85% or more sequence identity with the base sequence shown in SEQ ID NO: 7, comprising a region consisting of the base sequence shown in SEQ ID NO: 8 and a region consisting of the base sequence shown in SEQ ID NO:

9.

13. the viroid is one or more viroids selected from the group consisting of potato spindle tuber viroid (PSTVd) and chrysanthemum stunt viroid (CSVd); The plant crown gall disease control agent according to claim 5, wherein the plant is a plant of the Asteraceae family.

14. A method for controlling crown gall disease in plants, comprising a step of inoculating a plant with the agent for controlling crown gall disease according to any one of claims 1 to 13.

15. 15. The method for controlling crown gall disease in plants according to claim 14, wherein the plants are fruit trees, ornamental plants, or vegetables.

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