JP6748469B2 - Improvement of salt tolerance and/or osmotic tolerance of plants using bacteria of the genus Commonas - Google Patents

Description

The present invention provides a method for imparting salt tolerance and/or osmolarity to these plants by artificially infecting an agriculturally useful plant with an endophyte Comamonas genus bacterium, and Comamonas (Comamonas). ) A microbial preparation for imparting salt resistance and/or osmotic pressure resistance containing a genus bacterium and the like.

Crops are exposed to various environmental stresses, and if the environmental stresses exert a large load, yields will decrease. An example of environmental stress is salt damage caused by an increase in salt concentration in soil. Salt damage is mainly caused by the accumulation of salt in the soil due to poor drainage in irrigated agricultural land, but it may also be caused by the inflow of seawater in coastal areas and the accumulation of salt resulting from long-term fertilization during greenhouse cultivation. .. Salt damage has become a major problem on a global scale, and it has been reported that a decrease in crop production due to salt damage will reach $27.3 billion annually as an economic loss in the world (Non-Patent Document 1).

Optimization of drainage management of irrigated cultivated land is one of the important technologies for measures against salt damage. However, optimization of wastewater management often requires a large civil engineering machine and a large amount of water resources, and it takes a great deal of money and time to eliminate salt damage. Further, in order to improve the salt tolerance of the crop itself, attempts have been made to improve varieties by selecting breeding and mutants, and to produce enhanced strains by gene transfer and gene recombination. However, breeding by breeding or selection requires a great deal of time and labor to obtain varieties with desirable traits, and commercial cultivation of food crops obtained by genetic engineering is currently not performed in Japan. I have not been forgiven.
Therefore, there is a need for a simple method for improving the salt tolerance of plant crops.

M. Qadir et al., Natural Resource Forum, 2014, 38:282-295

It is an object of the present invention to easily impart salt and/or osmotic pressure resistance to plants useful in agriculture by microbiological means.

The present invention includes the following aspects.
(1) A step of artificially infecting a plant with a bacterium belonging to the genus Comamonas and having the ability to coexist in an agriculturally useful plant body and impart salt resistance and/or osmotic resistance to the plant. A method for imparting salt tolerance and/or osmotic tolerance to an agriculturally useful plant, which comprises:
(2) The agriculturally useful plant is a plant selected from the group consisting of a cruciferous plant, an Asteraceae plant, a leguminous plant, a Gramineae plant, a Solanaceae plant, a Liliaceae plant, a Seriaceae plant, and a Cucurbitaceae plant. The method according to (1).
(3) The method according to (1) or (2), wherein the bacterium has 16S rDNA containing a nucleotide sequence having 97% or more identity with the nucleotide sequence shown in SEQ ID NO: 1.
(4) The bacterium has the ability to coexist in Comamonas sp. MYK102 (Accession No. NITE P-01769) or in an agriculturally useful plant body to impart salt tolerance and/or osmotic resistance to the plant, The method according to any one of (1) to (3), which is a mutant strain.
(5) The method according to (1) or (2), wherein the bacterium has 16S rDNA containing a base sequence having 97% or more identity with the base sequence shown in SEQ ID NO: 2.
(6) The bacterium has the ability to coexist in Comamonas sp. MYK103 (Accession No. NITE P-01770) or in an agriculturally useful plant to impart salt tolerance and/or osmotic tolerance to the plant, The method according to (1), (2), or (5), which is a mutant strain.
(7) Agriculturally useful, which contains, as an active ingredient, a bacterium belonging to the genus Comamonas and having the ability to coexist in an agriculturally useful plant body and impart salt tolerance and/or osmotic pressure resistance to the plant. Microbial formulations for increasing salt tolerance and/or osmotic tolerance of plants.
(8) The plant useful for agriculture is selected from the group consisting of cruciferous plants, asteraceae plants, legume plants, gramineous plants, solanaceous plants, lily plants, seriaceous plants, and cucurbitaceous plants. The microbial preparation according to (7).
(9) The bacterium has the ability to coexist in Comamonas sp. MYK102 (Accession No. NITE P-01769) or in an agriculturally useful plant body to impart salt tolerance and/or osmotic pressure resistance to the plant, The microbial preparation according to (7) or (8), which is a mutant strain.
(10) The bacterium has the ability to coexist in Comamonas sp. MYK103 (Accession No. NITE P-01770) or in an agriculturally useful plant to impart salt tolerance and/or osmotic tolerance to the plant, The microbial preparation according to (7) or (8), which is a mutant strain.

As used herein, the term "Comamonas bacterium" refers to an endophytic bacterium that has the ability to symbiosis in an agriculturally useful plant to impart salt tolerance and/or osmotic tolerance to the plant. Generally, the term "endophyte" refers to a microorganism that is symbiotic with a plant.

According to the present invention, a microbiological means, that is, a bacterium belonging to the genus Comamonas that can be used as an endophyte (for example, MYK102 strain or MYK103 strain) is easily imparted salt tolerance and/or osmotic tolerance to an agriculturally useful plant. It becomes possible.

1. Bacteria Bacteria that can be used in the present invention are bacteria belonging to the genus Comamonas, and are useful for agricultural purposes, for example, cruciferous plants, asteraceae plants, legumes, grasses, and eggplants. A bacterium having the ability of symbiotic in the body of a plant selected from the group consisting of plants, lilies, plants of the Umbelliferae, and plants of the family Cucurbitaceae to impart salt tolerance and/or osmotic resistance to the plant. There is no particular limitation.

As used herein, a bacterium belonging to the genus Comamonas is an endophytic bacterium capable of imparting one or both of the above-mentioned abilities to a plant, and is not only a bacterium isolated from the natural world, but also such a bacterium. It also includes a mutant produced by subjecting the above to a mutation treatment.

As a specific example of the bacterium, a Comamonas genus bacterium, Comamonas sp. MYK102 (accession number NITE P-01769; hereinafter, may be simply referred to as "MYK102 strain" or "NITE P-01769 strain") or Comamonas sp .MYK103 (accession number NITE P-01770; hereinafter sometimes simply referred to as "MYK103 strain" or "NITE P-01770 strain"), or a mutant strain thereof having one or both of the above capabilities To be

The above-mentioned Comamonas sp. MYK102 and Comamonas sp. MYK103 are strains isolated from wild chrysanthemum. On December 27, 2013, Comamonas sp. MYK102 and Comamonas sp. MYK103 were registered as domestic depository institutions, the Japan Institute for Product Evaluation Technology, Patent Microorganism Depositary Center (Kazusa Kamaza, Kisarazu City, Chiba Prefecture 292-0818). 2-5-8) has been deposited by the applicant and has been given accession numbers NITE P-01769 and NITE P-01770, respectively. In addition, the indication of the identification of microorganisms in the trust certificate of "NITE P-01769" and "NITE P-01770" was originally "Delftia sp. MYK102" and "Delftia sp. MYK103", respectively. The display change was recognized on February 28, and was corrected to "Comamonas sp. MYK102" and "Comamonas sp. MYK103", respectively.

The MYK102 strain and the MYK103 strain are, for various bacterial genera and species, a partial sequence of the 16S rDNA gene (in this case, Comamonas sp.MYK102 (accession number NITE P-01769), SEQ ID NO: 1 and Comamonas sp. A homology search was performed using the MYK103 (accession number NITE P-01770) strain using SEQ ID NO:2). As a result, for Comamonas sp.MYK102, high sequence homology was confirmed for the top three highly homologous species: Comamonas koreensis strain IHB B 1392 and 99%, Comamonas sp.D1 and 99%, and Comamonas sp.TWNG17 and 99%. Therefore, it was identified as a bacterium belonging to the genus Comamonas. Further, Comamonas sp. MYK102 showed 97% sequence homology with Delftia sp. TS40.

Similarly, for Comamonas sp.MYK103, high sequence homology was confirmed for the top three highly homologous species: Comamonas koreensis strain IHB B 1392 and 99%, Comamonas sp. D1 and 99%, and Comamonas sp.TWNG17 and 99%. Therefore, it was identified as a bacterium belonging to the genus Comamonas. Further, Comamonas sp. MYK103 showed 97% sequence homology with Delftia sp. TS40.

The MYK102 strain has the substrate-utilizing ability shown in Table 1, and the MYK103 strain has the substrate-utilizing ability shown in Table 2.

As the bacterium that can be used in the present invention, a bacterium having the ability to impart salt tolerance and/or osmotic resistance to the above plants equivalent to the MYK102 strain or the MYK103 strain, which is a novel Comamonas genus bacterium, for example, belongs to the genus Comamonas, A bacterium having any one or more of the above capabilities and having 16S rDNA containing at least a part of the nucleotide sequence shown in SEQ ID NO: 1 or SEQ ID NO: 2 or a sequence equivalent to the nucleotide sequence, and belonging to the genus Comamonas , A bacterium having one or both of the above-mentioned capabilities and having the above-mentioned substrate-utilizing ability substantially equivalent to the MYK102 strain or the MYK103 strain, but not limited thereto. Here, the sequence equivalent to the base sequence shown in SEQ ID NO: 1 or 2 is preferably 97% or more, 98% or more, or 99% or more, more preferably 99.5% or more with the base sequence shown in SEQ ID NO: 1 or 2. , 99.7% or higher, 99.8% or higher, or 99.9% or higher identity. The identity value indicates a value calculated by default setting using software (for example, FASTA, DANASYS, and BLAST) that calculates the identity between a plurality of nucleotide sequences. In addition, having substantially the same substrate assimilating ability means that among the assimilating substrates shown in Table 1 or Table 2 which are not assimilating, as compared with the substrate assimilating ability of the MYK102 strain or the MYK103 strain. Is several or less, for example, three or less, two or less, or one.

Furthermore, the MYK102 strain or MYK103 strain is a mutant strain produced by artificially performing mutagenesis treatment, and is an agriculturally useful plant, for example, a cruciferous plant, an Asteraceae plant, a leguminous plant, a grass family plant. , A mutation having the ability to coexist in the body of a plant selected from the group consisting of solanaceous plants, lily plants, umbilical plants, and cucurbitaceae plants to impart salt resistance and/or osmotic resistance to the plants. Strains can also be used in the present invention.

When the Comamonas bacterium that can be used in the present invention is isolated from the natural world, the roots, stems, leaves, and the like of agriculturally useful plants are isolated from the plant constituent parts by culturing, and the bacteria which are symbiotic to the plant are cultured, One or both of them may be subjected to a selection test for sequence identity with the nucleotide sequence shown in SEQ ID NO: 1 or SEQ ID NO: 2 and/or for substrate assimilation.

In addition, when the mutagenesis treatment is performed, the MYK102 strain or the MYK103 strain can be mutated using any appropriate mutagen.

Here, the term "mutagen" has a broad meaning, and includes not only a drug having a mutagenic action but also a treatment having a mutagenic action such as high energy ray irradiation such as UV irradiation. Examples of suitable mutagens include ethyl methanesulfonate, UV irradiation, gamma irradiation, X-ray irradiation, heavy ion beam irradiation, nucleotide base analogs such as N-methyl-N'-nitro-N-nitrosoguanidine, bromouracil. , And acridines, but any other effective mutagen can also be used.

Alternatively, as another means for introducing a mutation into bacteria, there is a method using a gene recombination method.

The bacterium used in the present invention can be cultivated by a usual culturing method such as shaking culturing under the conditions usually used for Comamonas genus bacteria. As the medium used for culture, glucose, sucrose, starch, sugars such as dextrin as a carbon source, ammonium sulfate as a nitrogen source, ammonium chloride, ammonium salts such as ammonium nitrate, inorganic nitrogen sources such as nitrate, or yeast extract, corn. Organic nitrogen sources such as steep liquor, meat extract, wheat germ, polypeptone, sugar cane shavings (baccas), beer dregs, soybean flour, rice bran, and fish meal are used as inorganic salts of potassium monophosphate, magnesium sulfate, manganese sulfate, and sulfate sulfate. Examples of the medium include synthetic or natural media containing salts such as iron, etc., each containing phosphorus, potassium, manganese, magnesium, iron and the like. The culture temperature is usually 20 to 37° C., preferably 27 to 32° C., and the culture can be performed for 12 to 48 hours under aerobic conditions.

In the method of the present invention, the culture solution of bacteria can be used as it is, but a high concentration product of bacteria obtained by separating the culture solution of bacteria by a method such as membrane separation, centrifugation or filtration separation can also be used. ..

In the method of the present invention, a dried bacterial culture can also be used. In addition, it is possible to use a product obtained by adsorbing a bacterial culture solution to a porous adsorbent such as activated carbon, diatomaceous earth, talc, zeolite, peat moss, perlite, bentonite, montmorillonite, vermiculite, etc., and drying. One kind of porous adsorbent may be used, or a plurality of carriers may be used in combination. The drying method may be an ordinary method, for example, freeze drying or vacuum drying. These dried materials may be further crushed by a crushing means such as a ball mill after drying.

The bacterium can be used alone in the application of the present invention as the above-mentioned culture solution, high-concentration product or dried product, but it can be used in combination with other optional components in the same form as a normal microbial preparation (for example, powder formulation). , Wettable powder, granules, emulsions, solutions, suspensions, flowable agents, coating agents, etc.). Examples of optional components that can be used in combination include solid carriers, auxiliary substances, and other materials that are acceptable for application to plants.

2. Agriculturally useful plants The target plants that can be used in the method of the present invention are not limited to the following, but include, for example, Brassicaceae plants, Asteraceae plants, Legume plants, Gramineae plants, Solanaceae plants, Liliaceae plants, Selected from the group consisting of plants belonging to Umbelliferae and plants belonging to the family Cucurbitaceae, preferably selected from the group consisting of plants belonging to the family Asteraceae, legumes, solanaceous plants, plants belonging to the family Liliaceae, plants belonging to the family Uliaceae, and plants belonging to the family Cucurbitaceae. Useful plants are mentioned.

As used herein, “agriculturally useful plant” refers to a plant such as vegetables, cereal plants, and other crops, fruit trees, and other plants to be produced in agriculture.

Examples of cruciferous plants include canola, turnip, bok choy, nozawana, mustard, tacana, kobuta cana, mizuna, kohlraby, arugula, watercress, taasai, cauliflower, cabbage, kale, Chinese cabbage, komatsuna, radish, radish, broccoli, cabbages, wasabi. , Horseradish, and Arabidopsis.

Examples of the Asteraceae plant include lettuce, sunny lettuce, chrysanthemum, chrysanthemum, and the like.

Examples of legumes include soybean, azuki bean, peanut, kidney bean, pea, lentil, broad bean, cowpea, chickpea, mung bean, lentil, lima bean, bambara groundnut.

Examples of grasses include cereals such as rice, wheat, barley, rye, triticale, adlay, sorghum, oat, corn, sugar cane, millet and millet. Examples of grasses include feed or grass such as grass, buffalo grass, bermudagrass, weeping grass, centipede grass, carpet grass, dallis grass, kikuyu grass and St. Augustine grass.

Examples of the solanaceous plant include eggplant, tomato, bell pepper, citrus pepper, capsicum, potato, wolfberry, paprika, jalapeno, habanero and the like.

Examples of Liliaceae plants include onions, leeks, lacquer, garlic, leeks, Asatsuki, lilies, asparagus, shallots and scallions.

Examples of plants of the Umbelliferae family include carrots, honeywort, parsley, celery, celery, ashitaba, soup celery, charvel, and fennel.

Examples of the Cucurbitaceae plant include cucumber, pumpkin, bitter gourd, watermelon, zucchini, squirrel, loofah, melon, sardine and the like.

3. Method for Conferring Salt Tolerance and/or Osmotic Tolerance In one aspect, the present invention provides a bacterium belonging to the genus Comamonas, which has the ability to impart salt tolerance and/or osmotic tolerance to the plant, Provided is a method for imparting salt tolerance and/or osmotic tolerance to an agriculturally useful plant, which comprises a step of artificially infecting the plant.

In the present specification, “to impart salt tolerance to a plant” means to reduce growth (growth) inhibition or yield reduction due to salt stress in the presence of salt stress. Similarly, in the present specification, "to impart osmotic resistance to a plant" refers to reducing growth (growth) inhibition or yield reduction due to osmotic stress in the presence of osmotic stress. Whether or not salt tolerance and/or osmotic pressure resistance was imparted by inoculation of the bacterium of the present invention depends on the plant inoculated with the bacterium of the present invention in the presence of salt stress and/or osmotic stress, and the bacterium of the present invention. It can be examined by comparing the growth (growth) or yield of a control not inoculated with.

In the present specification, the “salt stress” means an environmental stress in which the growth (growth) or the yield of a plant is inhibited by a high salt concentration in a cultivation medium (for example, soil and a solid or liquid medium). .. The type of salt that causes salt stress is not particularly limited, and examples thereof include hydrochlorides such as NaCl, KCl, MgCl ₂ , and CaCl ₂ , and sulfates such as Na ₂ SO ₄ , MgSO ₄ , and CaSO _4. .. Although the sensitivity to salt stress may vary depending on the plant, the specific degree of salt stress that can impart resistance by the method of the present invention is appropriately determined by those skilled in the art in consideration of the family and species of plants. be able to. For example, salt stress may be the stress that occurs when continuously exposed to NaCl at a concentration of 50 mM to 600 mM for 1 hour to several weeks. It is known that salt stress inhibits the growth of plants mainly by two mechanisms, that is, a decrease in water absorption due to an increase in extracellular fluid osmotic pressure due to a high salt concentration, and an inhibition of an enzymatic reaction in a living body due to salt. Has been.

In the present specification, “osmotic stress” means environmental stress in which plant growth (growth) or yield is inhibited by the difference in osmotic pressure between the intracellular and extracellular solutions. The osmotic stress may be a high osmotic stress caused by a high osmotic external liquid or a low osmotic stress caused by a low osmotic external liquid, but is preferably a high osmotic stress. The type of solute that causes osmotic stress is not particularly limited, and examples thereof include the above salts and sugars such as glucose. Although susceptibility to osmotic stress may vary depending on the plant, the specific degree of osmotic stress that can impart resistance by the method of the present invention is appropriately determined by those skilled in the art in consideration of plants and species of plants. You can decide. For example, osmotic stress may be the stress that occurs when continuously exposed to NaCl at a concentration of 50 mM to 600 mM for 1 hour to several weeks.

The method of the present invention may be carried out, for example, on a plant that grows in an arid region or a region near the coast, and a plant that grows in a soil in which seawater flows in or a soil in which salts are accumulated due to long-term cultivation or the like. You can

Examples of the method of applying to plants include a method of seed coating, irrigation of young plants, application, or spray treatment. In particular, a method in which seeds or plants are arbitrarily artificially scratched and the bacterial solution is sprayed and applied is preferable. As other application conditions, it is desirable to apply the seedlings before planting in the field such as seedling raising period. Further, it is expected that high effects can be expected by spraying the plants, and in some cases the soil around the roots of the plants, during field cultivation.

As one example, in order to artificially infect a plant with the bacterium of the present invention, a bacterial solution is sprayed on a seedling before being planted in a field (for example, a seedling at the time when 1 to 4 true leaves appear). be able to. In this case, seedlings can be planted in the field about 1 to 15 days after spraying. It is considered that the fungus invading the plant eventually becomes symbiotic with the plant.

The concentration of the bacterial solution is 1×10 ⁵ to 1×10 ¹² cells/ml, for example, 1×10 ⁸ to 1×10 ¹⁰ cells/ml or more, but is not limited to these concentration ranges. The medium for suspending the bacteria is preferably water, a buffer solution or a medium. Usually, a highly concentrated bacterial solution can be diluted with water or a medium to a predetermined concentration before use.

4. Microbial Preparation The present invention further comprises, as an active ingredient, a bacterium belonging to the genus Comamonas, which has the ability to symbiotic in an agriculturally useful plant and impart salt tolerance and/or osmotic tolerance to the plant, Provided is a microbial preparation for imparting salt tolerance and/or osmotic tolerance to an agriculturally useful plant.

Examples of agriculturally useful plants include those specifically exemplified above from the cruciferous plant, the asteraceae plant, the legume plant, the gramineous plant, the solanaceous plant, the lily family plant, the celery family plant, and the cucurbitaceae plant. A plant selected from the group consisting of

A preferred bacterium is Comamonas sp. MYK102 (accession number NITE P-01769) or Comamonas sp. MYK103 (accession number NITE P-01770), or symbiotic in an agriculturally useful plant body, salt tolerance and/or penetration into the plant. It is a mutant strain thereof having the ability to impart pressure resistance.

As the microbial preparation, a high-concentration product of bacteria, a product obtained by drying a culture solution of bacteria, or the like can be used. In addition, it is possible to use a product obtained by adsorbing a bacterial culture solution to a porous adsorbent such as activated carbon, diatomaceous earth, talc, zeolite, peat moss, perlite, bentonite, montmorillonite, vermiculite, etc., and drying. One kind of porous adsorbent may be used, or a plurality of carriers may be used in combination. The drying method may be an ordinary method, for example, freeze drying or vacuum drying. These dried materials may be further crushed by a crushing means such as a ball mill after drying.

The bacterium can be used alone in the application of the present invention as the above-mentioned culture solution, high-concentration product or dried product, but it can be used in combination with other optional components in the same form as a normal microbial preparation (for example, powder formulation). , Wettable powder, granules, emulsions, solutions, suspensions, flowable agents, coating agents, etc.). Examples of optional components that can be used in combination include solid carriers, auxiliary substances, and other materials that are acceptable for application to plants.

Hereinafter, the present invention will be described in more detail with reference to examples, but the technical scope of the present invention is not limited to the examples.

[Example 1: Improvement of salt resistance and osmotic pressure resistance of lettuce cultivated in an artificial weather machine by MYK102 strain]
1) Method Lettuce coat seeds (variety: frilled ice) were sown on a urethane mat dipped in a hydroponic solution (1/2 dilution of OAT house fertilizer A formulation), and the seeds were cultivated in a climate machine at 22°C with a light period of 16 Cultivation was carried out for 1 week at a dark period of 8 hours.
The Comamonas sp. MYK102 strain was shake-cultured in a liquid medium for 24 hours. The culture solution was collected and washed, and the bacterial solution adjusted to a bacterial density of 1.0 × 10 ⁹ cells / ml was inoculated to the plant after one true leaf was developed at 100 µl per plant. After developing two true leaves, the leaves were replaced with a hydroponic solution containing 100 mM NaCl or 20% (w/w) polyethylene glycol (PEG) and treated with salt stress or osmotic stress.
The fresh weight of the plant one week after the stress treatment was measured. The same test was repeated 3 times with 12 plants per treatment group.

2) Results
In the 100 mM NaCl-treated group and the 20% (w/w) PEG-treated group, the fresh weight of the plants was increased by 33% and 13%, respectively, compared to the untreated group (Tables 3 and 4). This was a high value as compared to the 7% increase in lettuce yield when the MYK102 strain was inoculated without salt stress and osmotic stress (data not shown). These results suggest that inoculation of strain MYK102 improves salt and osmotic tolerance of lettuce.

[Example 2: Improvement of salt tolerance of greenhouse-grown lettuce by MYK102 strain]
1) Method A cell tray was filled with the culture soil, and 3 lettuce seeds (variety: Green Wave) were sown in each cell, 3 grains per cell. After developing one true leaf, one plant was thinned out per cell. MYK102 strain was cultivated in a liquid medium for 24 hours with shaking, and a culture solution adjusted to a bacterial density of 1.0 × 10 ⁹ cells / ml was inoculated to the plants after thinning at 100 μl per plant, and cultivated in a glass greenhouse. did.
After developing two true leaves, 0.5 M NaCl water was added to the plants, salt stress treatment was carried out, and the plants were cultivated until four or more true leaves were developed, and then the plants were excised from the edge part and harvested. Fresh weight was weighed after removing the leaves from the plants. The same test was repeated 3 times with 12 plants per treatment group.

2) Results
The fresh weight of the plant was increased by 20% in the 0.5M NaCl-treated group as compared with the untreated group (Table 5). This was higher than the 7% increase in lettuce yield when the MYK102 strain was inoculated without salt stress (data not shown). This result suggests that inoculation of MYK102 strain improves salt tolerance of lettuce.

[Example 3: Improvement of salt tolerance of greenhouse-grown leeks by MYK102 strain]
1) Method As a plant, onion seeds (variety: Otaru Onion) were sown. After developing one true leaf, one plant was thinned out per cell. MYK102 strain was cultivated in a liquid medium for 24 hours with shaking, and a culture solution adjusted to a bacterial density of 1.0 × 10 ⁹ cells / ml was inoculated to the plants after thinning at 100 μl per plant, and cultivated in a glass greenhouse. did.
After the development of two true leaves, 100 mM NaCl water was added to the plants, salt stress treatment was performed, and the plants were cultivated until three or more true leaves were developed, and then the plants were excised from the edge and harvested. Fresh weight was weighed after removing the leaves from the plants. The same test was repeated 3 times with 12 plants per treatment group.

2) Results
In the 100 mM NaCl-treated group, the fresh weight of the plant was increased by 33% as compared with the untreated group (Table 6). This was a high value compared to the 23% yield increase of leeks when the MYK102 strain was inoculated without salt stress (data not shown). This result suggests that inoculation of the MYK102 strain improves salt tolerance in leeks.

[Example 4: Improvement of salt stress of greenhouse-grown carrots by MYK102 strain]
1) Method The culture soil was filled in a cell tray, and 3 carrot seeds (cultivar: Gojin ginseng) were sown in each cell, 3 grains per cell. After developing one true leaf, one plant was thinned out per cell. MYK102 strain was cultivated in a liquid medium for 24 hours with shaking, and a culture solution adjusted to a bacterial density of 1.0 × 10 ⁹ cells / ml was inoculated to the plants after thinning at 100 μl per plant, and cultivated in a glass greenhouse. did.
After the development of two true leaves, 100 mM NaCl water was added to the plants, salt stress treatment was performed, and the plants were cultivated until three or more true leaves were developed, and then the plants were excised from the edge and harvested. Fresh weight was weighed after removing the leaves from the plants. The same test was repeated 3 times with 12 plants per treatment group.

2) Results
In the 100 mM NaCl-treated group, the fresh weight of plants was increased by 12% as compared with the untreated group (Table 7). This was a high value as compared with the 7% yield increase of carrots when the MYK102 strain was inoculated without salt stress (data not shown). This result suggests that inoculation of the MYK102 strain improves carrot salt tolerance.

[Example 5: Improvement of salt stress of greenhouse-grown soybean by MYK102 strain]
1) Method The culture soil was filled in a cell tray, and 3 soybean seeds (variety: early edamame) were sown for each cell. After developing one true leaf, one plant was thinned out per cell. MYK102 strain was cultivated in a liquid medium for 24 hours with shaking, and a culture solution adjusted to a bacterial density of 1.0 × 10 ⁹ cells / ml was inoculated to the plants after thinning at 100 μl per plant, and cultivated in a glass greenhouse. did.
After developing two true leaves, 0.5 M NaCl water was added to the plants, salt stress treatment was carried out, and the plants were cultivated until four or more true leaves were developed, and then the plants were excised from the edge part and harvested. Fresh weight was weighed after removing the leaves from the plants. The same test was repeated 3 times with 12 plants per treatment group.

2) Results
In the 0.5 M NaCl-treated group, the fresh weight of plants was increased by 20% as compared with the untreated group (Table 8). This was a high value compared to the 9% yield increase of soybean when the MYK102 strain was inoculated without salt stress (data not shown). This result suggests that inoculation of MYK102 strain improves salt tolerance in soybean.

[Example 6: Improvement of salt stress of greenhouse-grown cucumber by MYK102 strain]
1) Method The culture soil was filled in a cell tray, and one cucumber seed (cultivar: crawl without frost) was sown for each cell. After developing one true leaf, one plant was thinned out per cell. MYK102 strain was cultivated in a liquid medium for 24 hours with shaking, and a culture solution adjusted to a bacterial density of 1.0 × 10 ⁹ cells / ml was inoculated to the plants after thinning at 100 μl per plant, and cultivated in a glass greenhouse. did.
After developing two true leaves, 0.5 M NaCl water was added to the plants to treat them with salt stress, and the plants were cultivated until three or more true leaves were developed. Then, the plants were excised from the edge and harvested. Fresh weight was weighed after removing the leaves from the plants. The same test was repeated 3 times with 12 plants per treatment group.

2) Results
In the 0.5 M NaCl-treated group, the fresh weight of plants was increased by 12% as compared with the untreated group (Table 9). This was a high value compared to the 3% increase in cucumber yield when the MYK102 strain was inoculated without salt stress (Table 10). This result suggests that inoculation of the MYK102 strain improves the salt tolerance of cucumber.

[Example 7: Improvement of salt stress of greenhouse-grown tomatoes by MYK102 strain]
1) Method The culture soil was filled in a cell tray, and one tomato seed (variety: strong rice longevity) was sown for each cell. After developing one true leaf, one plant was thinned out per cell. MYK102 strain was cultivated in a liquid medium for 24 hours with shaking, and a culture solution adjusted to a bacterial density of 1.0 × 10 ⁹ cells / ml was inoculated to the plants after thinning at 100 μl per plant, and cultivated in a glass greenhouse. did.
After developing two true leaves, 100 mM NaCl water was added to the plants, salt stress treatment was performed, and the plants were cultivated until four or more true leaves were developed, and then the plants were excised from the edge and harvested. Fresh weight was weighed after removing the leaves from the plants. The same test was repeated 3 times with 12 plants per treatment group.

2) Results
In the 100 mM NaCl-treated group, the fresh weight of plants was increased by 9% as compared with the untreated group (Table 11). This was a high value as compared to the 1% yield increase of tomato (Table 12) when the MYK102 strain was inoculated without salt stress. This result suggests that inoculation of MYK102 strain improves salt tolerance of plants.

INDUSTRIAL APPLICABILITY The present invention artificially infects agriculturally useful plants with Comamonas spp. bacteria, thereby imparting salt tolerance and/or osmotic resistance to these plants, and thus is useful agriculturally.

Claims (4)

A step of artificially infecting a plant with a bacterium belonging to the genus Comamonas, which has the ability to symbiotic in an agriculturally useful plant body to impart salt tolerance and/or osmotic tolerance to the plant, However, when the bacterium is Commonas sp. MYK102 (accession number NITE P-01769), Commonas sp. MYK103 (Accession No. NITE P-01770), or a mutant strain of MYK102 or MYK103, which has the ability to symbiotically grow into a plant useful in agriculture and impart salt tolerance and/or osmotic tolerance to the plant, A method for imparting salt tolerance and/or osmotic tolerance to an agriculturally useful plant. Agriculturally useful plants are plants selected from the group consisting of cruciferous plants, asteraceae plants, legumes, gramineous plants, solanaceous plants, lily plants, seriaceous plants, and cucurbitaceae plants, The method of claim 1. As an active ingredient, a bacterium belonging to the genus Commonas and having the ability to coexist in an agriculturally useful plant body to impart salt tolerance and/or osmotic resistance to the plant, provided that the bacterium is a Commonas sp. ． MYK102 (accession number NITE P-01769), Commonas sp. MYK103 (Accession No. NITE P-01770), or a mutant strain of MYK102 or MYK103, which has the ability to symbiotically grow into a plant useful in agriculture and impart salt tolerance and/or osmotic tolerance to the plant, A microbial preparation for increasing salt tolerance and/or osmotic tolerance of an agriculturally useful plant. Agriculturally useful plants are plants selected from the group consisting of cruciferous plants, asteraceae plants, legumes, gramineous plants, solanaceous plants, lily plants, seriaceous plants, and cucurbitaceae plants, The microbial preparation according to claim 3 .