Plant growth-promoting rhizobacteria for enhancing salt tolerance of wheat and application of plant growth-promoting rhizobacteria

Abstract

The invention provides a growth-promoting rhizobacteria for enhancing salt tolerance of wheat and application of the growth-promoting rhizobacteria, and belongs to the technical field of agricultural microorganisms. The invention provides stenotrophomonas maltophilia TJ3-57, and the preservation number of the stenotrophomonas maltophilia TJ3-57 is GDMCC (Graphical Digital Microbial Counter Center) The stenotrophomonas maltophilia TJ3-57 can improve the salt stress resistance of plants, relieve the damage of salt stress to the plants and promote the growth of the plants in the saline-alkali soil, so that the yield of crops in the saline-alkali soil is increased.

Description

Technical Field

[0001] The present invention belongs to the technical field of agricultural microorganisms, and specifically relates to a plant growth-promoting rhizobacterium for enhancing the salt tolerance of wheat and its application. Background Art

[0002] Soil salinization is a global problem that has a significant impact on food security, arable land security, and ecological security.

[0003] Microbial inoculants are live bacterial preparations obtained through a series of processes including screening functional strains, industrial scale-up cultivation, adsorption of bacterial cells, and fermentation. Microbial inoculants can be applied in various agricultural productions, and have obvious effects in improving soil, restoring soil fertility, etc., and can also prevent and control many diseases and pests, effectively improving the quality and yield of crops, thereby achieving the goals of increasing production and protecting the ecological environment. Microbial inoculants exert their effects through the interactions between microorganisms, between microorganisms and fertilizers, between microorganisms and plants, between microorganisms and soil, between microorganisms and plants, and between microorganisms and soil. The use of microbial inoculants reduces the usage amount of chemical fertilizers and pesticides in agricultural production and improves the quality of agricultural production. There have also been great progresses in the research and development of microbial inoculants in China, and good results have been achieved in aspects such as water purification and garbage treatment. In addition, certain progresses have also been made in the efficient screening of beneficial bacteria. However, at present, there are no relevant reports on Stenotrophomonas maltophilia in improving saline-alkali soil and simultaneously improving the quality of agricultural production. Summary of the Invention

[0004] The purpose of the present invention is to provide a Stenotrophomonas maltophilia that can improve the salt stress tolerance of crops in saline-alkali land and increase the yield of crops in saline-alkali land.

[0005] The purpose of the present invention is achieved through the following technical solutions:

[0006] The present invention provides a Stenotrophomonas maltophilia TJ3-57 with a preservation number of GDMCC NO.64978.

[0007] The present invention provides a microbial inoculant comprising the Stenotrophomonas maltophilia TJ3-57 described in the above technical solution.

[0008] Preferably, the OD value of Stenotrophomonas maltophilia TJ3-57 in the microbial inoculant 600 is ≥1.0.

[0009] The present invention provides a preparation method of the microbial inoculant described in the above technical solution, including:

[0010] Cultivate the Stenotrophomonas maltophilia TJ3-57 in a culture medium to obtain a microbial inoculum.

[0011] Preferably, the temperature of the cultivation is 28-37 °C; the time of the cultivation is 24-36 h; rotation is accompanied during the cultivation, and the rotation speed is 150-230 rpm.

[0012] The present invention provides the application of the Stenotrophomonas maltophilia TJ3-57 described in the above technical solution in promoting plant growth and / or improving the salt tolerance of plants.

[0013] Preferably, the plant includes wheat.

[0014] Preferably, the promotion of plant growth includes promoting the improvement of any one or more of the following indexes (1)-(6):

[0015] (1) Plant height;

[0016] (2) Root length;

[0017] (3) Fresh weight of the above-ground part;

[0018] (4) Fresh weight of roots;

[0019] (5) Dry weight of the above-ground part;

[0020] (6) Dry weight of roots.

[0021] Preferably, the improvement of the salt tolerance of plants includes alleviating the damage of salt stress to plants and / or improving the salt stress tolerance of plants.

[0022] The present invention provides a method for improving the salt tolerance of plants, including:

[0023] After the plant grows to the two-leaf and one-heart stage, apply a microbial inoculum including the Stenotrophomonas maltophilia TJ3-57 described in the above technical solution.

[0024] The beneficial effects of the present invention:

[0025] The present invention provides a Stenotrophomonas maltophilia TJ3-57 with a preservation number of GDMCC NO.64978. In the present invention, the Stenotrophomonas maltophilia TJ3-57 can improve the salt stress tolerance of plants, alleviate the damage of salt stress to plants, promote the growth of plants in saline-alkali land, and thus contribute to increasing the yield of crops on saline-alkali land. The results of the examples in the present invention show that the Stenotrophomonas maltophilia TJ3-57 can promote the germination of wheat under salt stress, significantly increase the plant height, root length, above-ground fresh weight, root fresh weight, above-ground dry weight and root dry weight of wheat under salt stress conditions, and reduce the malondialdehyde content, thereby promoting the growth of wheat under salt stress conditions and alleviating the damage of salt stress to wheat. In summary, the Stenotrophomonas maltophilia TJ3-57 provided by the present invention is beneficial to improving the salt stress tolerance of crops on saline-alkali land and increasing the yield of crops on saline-alkali land.

[0026] Biological preservation description

[0027] Stenotrophomonas maltophilia TJ3-57, classified and named as Stenotrophomonas maltophilia, was preserved in the Guangdong Provincial Microbial Culture Collection Center on May 8, 2024. The address is the 5th floor of the Experimental Building, No. 100, Xianlie Middle Road, Yuexiu District, Guangzhou, Guangdong Province, and the preservation number is GDMCC NO.64978. Description of the drawings

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0029] Figure 1 It is a statistical result diagram of the germination rate of wheat at different salt concentrations in Example 2;

[0030] Figure 2 It is a phenotypic observation result diagram of the whole wheat plants of the functional bacterium TJ3-57 and the blank control group at a salt concentration of 5‰;

[0031] Figure 3 It is a phenotypic observation result diagram of the wheat potted plants of the functional bacterium TJ3-57 and the blank control group at a salt concentration of 5‰;

[0032] Figure 4 It is a phenotypic observation result diagram of the whole wheat plants of the functional bacterium TJ3-57 and the blank control group at a salt concentration of 8‰;

[0033] Figure 5 Phenotype observation results of wheat potted plants of functional bacterium TJ3-57 and blank control group under 8‰ salt concentration;

[0034] Figure 6 Results of the effects of five functional bacteria on the plant height of wheat;

[0035] Figure 7 Results of the effects of five functional bacteria on the root length of wheat;

[0036] Figure 8 Results of the effects of five functional bacteria on the fresh weight of the above-ground part of wheat;

[0037] Figure 9 Results of the effects of five functional bacteria on the fresh weight of wheat roots;

[0038] Figure 10 Results of the effects of five functional bacteria on the dry weight of the above-ground part of wheat;

[0039] Figure 11 Results of the effects of five functional bacteria on the dry weight of wheat roots;

[0040] Figure 12 Results of the effects of five functional bacteria on the malondialdehyde content of wheat;

[0041] Figure 13 Phylogenetic analysis results of Stenotrophomonas maltophilia TJ3-57. Detailed implementation mode

[0042] The present invention provides a Stenotrophomonas maltophilia TJ3-57 with a preservation number of GDMCC NO.64978. In the present invention, the Stenotrophomonas maltophilia TJ3-57 is derived from the rhizosphere of the halophyte Sesbania cannabina. In the present invention, the nucleotide sequence of the 16S rDNA of the Stenotrophomonas maltophilia TJ3-57 is shown as SEQ ID NO.1. In the present invention, the Stenotrophomonas maltophilia TJ3-57 has been preserved in the Guangdong Provincial Microbial Culture Collection Center on May 8, 2024, with a preservation number of GDMCC NO.64978.

[0043] The present invention provides a microbial inoculum, including the Stenotrophomonas maltophilia TJ3-57 described in the above technical solution. As an optional implementation mode of the present invention, the OD 600 value of the Stenotrophomonas maltophilia TJ3-57 in the microbial inoculum is ≥ 1.0, and it can be 1.0.

[0044] The present invention provides a preparation method of the microbial inoculum described in the above technical solution, including:

[0045] Cultivate the Stenotrophomonas maltophilia TJ3-57 in a culture medium to obtain a microbial inoculum.

[0046] As an optional embodiment of the present invention, the culture medium can be a TSB liquid medium; the culture temperature can be 28-37°C, or 28, 29, 30, 31, 32, 33, 34, 35, 36 or 37°C; the culture time can be 24-36 h, or 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35 or 36 h; rotation is accompanied during the culture process, and the rotation speed can be 150-230 rpm, or 150, 160, 170, 180, 190, 200, 210, 220 or 230 rpm.

[0047] After the cultivation is completed, a Stenotrophomonas maltophilia TJ3-57 culture solution is obtained in the present invention. As an optional embodiment of the present invention, the Stenotrophomonas maltophilia TJ3-57 culture solution can be directly used as a microbial inoculum; or the cells in the Stenotrophomonas maltophilia TJ3-57 culture solution can be separated and resuspended to obtain a cell suspension as a microbial inoculum. The present invention has no special limitation on the separation method, and conventional methods in the art can be used. As an optional embodiment of the present invention, the separation method can be centrifugation. After the cells are separated in the present invention, the cells are resuspended with sterile water to obtain a cell suspension. As an optional embodiment of the present invention, the OD 600 value of Stenotrophomonas maltophilia TJ3-57 in the cell suspension ≥ 1.0, or 1.0.

[0048] The present invention provides the application of the Stenotrophomonas maltophilia TJ3-57 described in the above technical solution in promoting plant growth and / or improving plant salt tolerance. As an optional embodiment of the present invention, the plant includes wheat. As an optional embodiment of the present invention, promoting plant growth includes promoting the growth of plants under salt stress conditions. As an optional embodiment of the present invention, promoting plant growth includes promoting the improvement of any one or more of the following indexes (1)-(6): (1) plant height; (2) root length; (3) above-ground fresh weight; (4) root fresh weight; (5) above-ground dry weight; (6) root dry weight. In the present invention, improving plant salt tolerance includes alleviating the damage of salt stress to plants and / or improving the salt stress tolerance of plants. The results of the examples in the present invention show that the Stenotrophomonas maltophilia TJ3-57 can promote the germination of wheat under salt stress at salt concentrations of 5‰ and 8‰, significantly increase the plant height, root length, above-ground fresh weight, root fresh weight, above-ground dry weight and root dry weight of wheat under salt stress conditions, and reduce the malondialdehyde content, thereby promoting the growth of wheat under salt stress conditions and alleviating the damage of salt stress to wheat.

[0049] The present invention provides a method for improving the salt tolerance of plants, including:

[0050] After the plants grow to the two-leaf and one-heart stage, a microbial inoculant containing Stenotrophomonas maltophilia TJ3-57 described in the above technical solution is applied. As an optional implementation manner of the present invention, the timing of the application can be within 1 to 2 weeks after the plants grow to the two-leaf and one-heart stage. As an optional implementation manner of the present invention, the number of applications can be 2 times; the time interval between the two applications is two weeks; the application amount of Stenotrophomonas maltophilia TJ3-57 each time is 10 7 CFU / g soil, that is, 10 7 CFU of Stenotrophomonas maltophilia TJ3-57 is applied to each gram of soil.

[0051] In order to further illustrate the present invention, the technical solution provided by the present invention will be described in detail below in conjunction with the drawings and embodiments, but they cannot be understood as limiting the protection scope of the present invention.

[0052] The wheat variety used in the following technical solution is Bainong Aikang 58.

[0053] In the experimental methods in the following embodiments, unless otherwise specified, they are all conventional methods. The test materials used in the following embodiments, unless otherwise specified, are all purchased from conventional biochemical reagent stores. In the following quantitative tests, three repeated experiments are set, and the results are averaged.

[0054] Example 1 Construction of a strain resource library

[0055] Halophyte materials: Suaeda salsa, Sesbania cannabina, Tamarix chinensis, collected from a farm near the Yancheng Dafeng Milu National Park (32°59′46″ N, 120°49′48″ E); the halophyte Spartina alterniflora, collected from the tidal flat near the Yancheng Dafeng Huanghai National Forest Park (32°52′25″ N, 120°54′24″ E).

[0056] Using the method of metacultivationomics, the rhizosphere samples of halophytes are serially diluted with a buffer solution (PBS-S), and the rhizosphere sample suspensions with dilution gradients of 10 -6 and 10 -7 are cultured in TSB liquid medium in 96-well plates. After 14 days of culture, 96-well plates with a microbial growth probability of 30% to 50% are selected. In a sterile environment, 80 μL of the bacterial liquid is aspirated from the wells with growing microorganisms and added to a pcr tube containing 80 μL of 40% glycerol (aqueous glycerol solution with a glycerol volume fraction of 40%), gently pipetted and mixed well, labeled and placed in a -80 °C refrigerator for strain preservation, so as to obtain a halophyte rhizosphere strain resource library.

[0057] Experimental results: 3991 effective bacterial pores were isolated from the rhizospheres of four halophytes, Sesbania cannabina, Suaeda glauca, Spartina alterniflora, and Tamarix chinensis.

[0058] Example 2 Screening of functional bacterial strains

[0059] I. Determination of the critical salt concentration for wheat seed germination

[0060] 1. Select plump wheat seeds of uniform size for surface disinfection.

[0061] Immerse the seeds in an ethanol aqueous solution with a volume fraction of 75% ethanol for 1 minute, then rinse the ethanol on the seed surface with sterile water. Next, immerse the seeds in a sodium hypochlorite aqueous solution with a mass concentration of 2% sodium hypochlorite for 5 min, and rinse with sterile water 6 times.

[0062] 2. Immerse the wheat seeds surface-disinfected in step 1 in sterile sodium chloride solutions with different salt concentrations (0 mM, 40 mM, 80 mM, 120 mM, 160 mM, 200 mM, 240 mM) respectively. Each treatment has three replicates, with 10 seeds in each replicate. Immerse the seeds in the dark at 25 °C for 4 h.

[0063] 3. Place the seeds immersed in step 2 in a petri dish containing sterile wet filter paper with the corresponding salt concentration, and germinate the seeds in a 25 °C light incubator with a day-night ratio of 16 h / 8 h for 7 days.

[0064] 4. After completing step 3, count the germination rate of wheat seeds in different treatments (germination rate (%) = (number of normally germinated seeds on the 7th day of germination / number of tested seeds) × 100), and find the critical salt concentration for wheat seed germination.

[0065] Experimental results: According to the statistical results of the germination rate of wheat at different salt concentrations ( Figure 1 ), 200 mM was determined as the critical salt stress concentration for wheat germination.

[0066] II. Screening of bacterial pores

[0067] Bacterial strains to be tested: 3991 effective bacterial pores isolated in Example 1.

[0068] 1. Immerse the surface-disinfected wheat seeds in a 240 mM sodium chloride solution in the dark at 25 °C for 4 hours. The control group is immersed in sterile water.

[0069] 2. Place the seeds immersed in step 1 in a petri dish containing sterile water and a 240 mM sodium chloride solution and lined with filter paper for cultivation. Each petri dish contains 3 seeds and has three replicates.

[0070] 3. Pipette 10 μL of the bacterial solution from each PCR tube of the halophyte bacterial strain resource library constructed in Example 1 into a 2 mL centrifuge tube containing 1 mL of TSB liquid medium, gently mix, and culture in a shaker at 30 °C and 170 rpm until OD 600 = 1.0.

[0071] 4. Drop 100 μL of the corresponding bacterial solution obtained in Step 3 directly above each treated wheat seed in Step 2, that is, add a valid bacterial pore corresponding to each treated wheat seed with the bacterial solution obtained through the above Step 3, and number them for distinction. Place them in a 25 °C light incubator to germinate, with a day-night ratio of 16 h / 8 h for 4 days.

[0072] 5. Observe the germination of different treatments in Step 4, and preliminarily screen out the bacterial pores that can promote wheat germination under salt stress conditions.

[0073] Use Bacillus amyloliquefaciens SQR9 (the preservation number is CGMCC NO. 5808, which has been disclosed in ZL201710797445.0) treatment as a positive control, only adding salt without adding bacteria treatment as a negative control, and not adding salt or bacteria treatment as CK.

[0074] Experimental results: According to the statistical results of the germination rate of wheat after inoculating different bacterial pores at a salt concentration of 240 mM, 33 bacterial pores that can promote wheat germination under salt stress were screened out.

[0075] III. Purification of strains

[0076] According to the preliminary screening results of the germination test under salt stress, find the bacterial pores that can promote wheat germination under 240 mM salt stress and isolate and purify single bacteria.

[0077] 1. Pipette the bacterial solution from the bacterial pores obtained by preliminary screening onto a TSB plate and culture it upside down at 30 °C for 24 h.

[0078] 2. Select single colonies with rapid growth and different morphologies in Step 1, and continue to streak and separate the remaining ones without single colonies on the TSB plate until single colonies appear.

[0079] 3. Then purify each single colony in Step 2 by streaking on a TSB plate 3 times.

[0080] 4. Pick the single colonies in Step 3 into a test tube containing 3 mL of TSB liquid medium, and shake the bacteria at 30 °C and 170 rpm until the bacterial solution becomes turbid.

[0081] 5. Pipette 80 μL of the bacterial solution in Step 4 into a tube containing 40% glycerol aqueous solution and store it in a -80 °C refrigerator.

[0082] According to the preliminary screening results of the crop germination test under salt stress, construct a single-bacteria resource library.

[0083] Experimental results: Five strains that can promote wheat germination under salt stress were purified, namely TJ3-57, TJ3-52, TJ1-293, J1-108, and J1-109.

[0084] Pot experiment verification of functional strains in Example 3

[0085] Test strains: Five strains screened in Example 2 and Bacillus amyloliquefaciens SQR9.

[0086] Tested soil materials: Saline-alkali soil from Cangdong Farm, Yancheng City, Jiangsu Province, divided into two salinity gradients (5‰ and 8‰). The pH of the 5‰ saline-alkali soil is 7.84, and the pH of the 8‰ saline-alkali soil is 7.80.

[0087] I. Preparation of bacterial suspension

[0088] 1. Inoculate the five screened functional strains and the control strain SQR9 (Bacillus amyloliquefaciens SQR9) into TSB liquid medium and culture at 30 °C and 170 rpm.

[0089] 2. After 24 h, centrifuge the bacterial liquid, and then resuspend the bacterial cells with sterile water to make the OD 600 value of the bacterial suspension 1.0.

[0090] II. Germination and seedling raising of wheat seeds

[0091] 1. First, sterilize the surface of wheat seeds. This step is carried out in a laminar flow hood. Select plump and basically uniform-sized Bainong Aikang 58 wheat seeds, disinfect the wheat seeds with an alcohol solution with a volume fraction of 75% ethanol for 1 min, then soak the wheat seeds in a sodium hypochlorite solution with a mass fraction of 2% for 5 min, and rinse with sterile ultrapure water 6 times to wash away the sodium hypochlorite solution attached to the seed surface.

[0092] 2. Place the soaked wheat seeds in a petri dish containing sterile water and lined with sterile filter paper, and germinate them in the dark at 25 °C for 4 days.

[0093] 3. Select the wheat seedlings with consistent growth in step 2 and transplant them into the seedling-raising substrate for seedling raising. When the wheat grows to the two-leaf and one-heart stage, select the wheat seedlings with consistent growth and transplant them into the designated soil for subsequent experiments.

[0094] III. Pot experiment design

[0095] This experiment was carried out in the greenhouse of the Baima Scientific Research Base of Nanjing Agricultural University, Nanjing City, Jiangsu Province from November 2023 to January 2024, and the experimental period was 28 days.

[0096] In this experiment, two salt gradients were set: 5‰ and 8‰. Each pot was filled with 500 g of soil. The experiment had a control group and a treatment group. In the control group, the potted plants were inoculated with either no bacteria (blank control group) or Bacillus amyloliquefaciens SQR9 (positive control group). In the treatment group, five functional strains were inoculated respectively.

[0097] 1. Select wheat seedlings with consistent growth in step 2 and transplant them into saline soil with two salt gradients (5‰ and 8‰). There are 5 wheat seedlings in each pot, and 3 pots are set as controls for each treatment. Cultivate at room temperature and appropriately water to maintain the soil moisture content.

[0098] 2. One week after wheat transplantation, the bacterial suspensions of five functional bacteria and the bacterial suspension of SQR9 were respectively watered around the roots of the seedlings, and the inoculation concentration of each bacterium was maintained at 10 7 CFU / g soil, that is, 10 7 CFU of bacteria were applied per gram of soil. Specifically, in this step: one kind of bacterium was inoculated in one wheat treatment group, the blank control group was not inoculated, and sterile water equal to the volume of the bacterial suspension was added. The positive control group was inoculated with Bacillus amyloliquefaciens SQR9.

[0099] 3. Two weeks later, the bacterial suspension was added again in the same way, and the same volume of sterile water was watered into each pot in the control group. Under the culture conditions of 30℃ and 16 / 8 h light, continue to grow for two weeks.

[0100] 4. After completing step 3, various physiological and biochemical indexes of wheat plants were measured.

[0101] The content of malondialdehyde (MDA) was detected using a commercially available kit (purchased from Nanjing Jiancheng Bioengineering Institute).

[0102] The measurement results of various physiological and biochemical indexes of wheat plants are shown in Tables 1 - 2 and Figures 2 to 12 as follows.

[0103] Figure 2 Figure shows the phenotypic observation results of the whole wheat plants of the functional bacterium TJ3 - 57 and the blank control group under the salt concentration of 5‰. Among them, the three plants on the left are the blank control group; the three plants on the right are the treatment group of the functional bacterium TJ3 - 57; Figure 3 Figure shows the phenotypic observation results of the wheat potted plants of the functional bacterium TJ3 - 57 and the blank control group under the salt concentration of 5‰. Among them, the two pots on the left are the blank control group; the two pots on the right are the treatment group of the functional bacterium TJ3 - 57; Figure 4 Figure shows the phenotypic observation results of the whole wheat plants of the functional bacterium TJ3 - 57 and the blank control group under the salt concentration of 8‰. Among them, the two plants on the left are the blank control group; the two plants on the right are the treatment group of the functional bacterium TJ3 - 57; Figure 5 Figure shows the phenotypic observation results of the wheat potted plants of the functional bacterium TJ3 - 57 and the blank control group under the salt concentration of 8‰. Among them, the two pots on the left are the blank control group; the two pots on the right are the treatment group of the functional bacterium TJ3 - 57.

[0104] Figure 6 Graph showing the effects of 5 functional bacteria on the plant height of wheat; among them, A shows the effects of 5 functional bacteria on the plant height of wheat under a salt concentration of 5‰, and B shows the effects of 5 functional bacteria on the plant height of wheat under a salt concentration of 8‰.

[0105] Figure 7 Graph showing the effects of 5 functional bacteria on the root length of wheat; among them, A shows the effects of 5 functional bacteria on the root length of wheat under a salt concentration of 5‰, and B shows the effects of 5 functional bacteria on the root length of wheat under a salt concentration of 8‰.

[0106] Figure 8 Graph showing the effects of 5 functional bacteria on the fresh weight of the above-ground parts of wheat; among them, A shows the effects of 5 functional bacteria on the fresh weight of the above-ground parts of wheat under a salt concentration of 5‰, and B shows the effects of 5 functional bacteria on the fresh weight of the above-ground parts of wheat under a salt concentration of 8‰.

[0107] Figure 9 Graph showing the effects of 5 functional bacteria on the fresh weight of wheat roots; among them, A shows the effects of 5 functional bacteria on the fresh weight of wheat roots under a salt concentration of 5‰, and B shows the effects of 5 functional bacteria on the fresh weight of wheat roots under a salt concentration of 8‰.

[0108] Figure 10 Graph showing the effects of 5 functional bacteria on the dry weight of the above-ground parts of wheat; among them, A shows the effects of 5 functional bacteria on the dry weight of the above-ground parts of wheat under a salt concentration of 5‰, and B shows the effects of 5 functional bacteria on the dry weight of the above-ground parts of wheat under a salt concentration of 8‰.

[0109] Figure 11 Graph showing the effects of 5 functional bacteria on the dry weight of wheat roots; among them, A shows the effects of 5 functional bacteria on the dry weight of wheat roots under a salt concentration of 5‰, and B shows the effects of 5 functional bacteria on the dry weight of wheat roots under a salt concentration of 8‰.

[0110] Figure 12 Graph showing the effects of 5 functional bacteria on the malondialdehyde content of wheat; among them, A shows the effects of 5 functional bacteria on the malondialdehyde content of wheat under a salt concentration of 5‰, and B shows the effects of 5 functional bacteria on the malondialdehyde content of wheat under a salt concentration of 8‰.

[0111] Table 1. Detection results (mean values) of various physiological and biochemical indexes of wheat plants in each treatment group under a salt concentration of 5‰

[0112]

[0113] Table 2. Detection results (mean values) of various physiological and biochemical indexes of wheat plants in each treatment group under a salt concentration of 8‰

[0114]

[0115] As shown in Tables 1 - 2 and Figures 2 to 12 it can be seen that the experimental results are as follows

[0116] I. As Figures 2 to 5 shown, under the influence of salt stress, the growth and development of wheat are severely inhibited. At a salt concentration of 5‰, the growth of wheat basically stagnates, while inoculation with the functional bacterium TJ3 - 57 can help wheat resume growth; at a salt concentration of 8‰, the growth of wheat is severely inhibited, with yellowing and curling of leaves, and inoculation with the functional bacterium TJ3 - 57 can help wheat survive.

[0117] II. As Figure 6 shown, with the increase in salt concentration, the plant height of wheat under high - salt stress (8‰) is significantly lower than that of wheat under low - salt stress (5‰). At both salt concentrations, the plant height of wheat seedlings treated with bacteria inoculation is significantly higher than that of the blank control treatment (CK) and the wheat under SQR9 treatment.

[0118] 1. At a salt concentration of 5‰, compared with the control group, the plant height of wheat inoculated with the functional bacterium TJ3 - 57 increased by 31.8% compared to the blank control.

[0119] 2. At a salt concentration of 8‰, compared with the control group, the plant height of wheat inoculated with the functional bacterium TJ3 - 57 increased by 73.6% compared to the blank control.

[0120] III. As Figure 7 shown, with the increase in salt concentration, the root length of wheat under high - salt stress (8‰) is significantly lower than that of wheat under low - salt stress (5‰). At both salt concentrations, the root length of wheat seedlings treated with bacteria inoculation is significantly higher than that of the blank control treatment (CK) and the wheat under SQR9 treatment.

[0121] 1. At a salt concentration of 5‰, compared with the control group, the root length of wheat inoculated with the functional bacterium TJ3 - 57 increased by 25.5% compared to the blank control.

[0122] 2. At a salt concentration of 8‰, compared with the control group, the root length of wheat inoculated with the functional bacterium TJ3 - 57 increased by 26.0% compared to the blank control.

[0123] IV. As Figure 8 shown, with the increase in salt concentration, the fresh weight of the above - ground part of wheat under high - salt stress (8‰) is significantly lower than that of wheat under low - salt stress (5‰). At both salt concentrations, the fresh weight of the above - ground part of wheat seedlings treated with bacteria inoculation is significantly higher than that of the blank control treatment (CK) and the wheat under SQR9 treatment.

[0124] 1. At a salt concentration of 5‰, compared with the control group, the fresh weight of the above-ground part of wheat inoculated with the functional bacterium TJ3-57 increased by 119.2% compared to the blank control.

[0125] 2. At a salt concentration of 8‰, compared with the control group, the fresh weight of the above-ground part of wheat inoculated with the functional bacterium TJ3-57 increased by 81.3% compared to the blank control.

[0126] V. As Figure 9 shown, with the increase in salt concentration, the fresh weight of the roots of wheat under high salt stress (8‰) was significantly lower than that of wheat under low salt stress (5‰). At both salt concentrations, the fresh weight of the roots of wheat seedlings treated with inoculation was significantly higher than that of the blank control treatment (CK) and the wheat roots under SQR9 treatment.

[0127] 1. At a salt concentration of 5‰, compared with the control group, the fresh weight of the roots of wheat inoculated with the functional bacterium TJ3-57 increased by 69.7% compared to the blank control.

[0128] 2. At a salt concentration of 8‰, compared with the control group, the fresh weight of the roots of wheat inoculated with the functional bacterium TJ3-57 increased by 74.8% compared to the blank control.

[0129] VI. As Figure 10 shown, with the increase in salt concentration, the dry weight of the above-ground part of wheat under high salt stress (8‰) was significantly lower than that of wheat under low salt stress (5‰). At both salt concentrations, the dry weight of the above-ground part of wheat seedlings treated with inoculation was significantly higher than that of the blank control treatment (CK) and the wheat above-ground part under SQR9 treatment.

[0130] 1. At a salt concentration of 5‰, compared with the control group, the dry weight of the above-ground part of wheat inoculated with the functional bacterium TJ3-57 increased by 61.0% compared to the blank control.

[0131] 2. At a salt concentration of 8‰, compared with the control group, the dry weight of the above-ground part of wheat inoculated with the functional bacterium TJ3-57 increased by 46.8% compared to the blank control.

[0132] VII. As Figure 11 shown, with the increase in salt concentration, the dry weight of the roots of wheat under high salt stress (8‰) was significantly lower than that of wheat under low salt stress (5‰). At both salt concentrations, the dry weight of the roots of wheat seedlings treated with inoculation was significantly higher than that of the blank control treatment (CK) and the wheat roots under SQR9 treatment.

[0133] 1. At a salt concentration of 5‰, compared with the control group, the dry weight of the roots of wheat inoculated with the functional bacterium TJ3-57 increased by 69.6% compared to the blank control.

[0134] 2. At a salt concentration of 8‰, compared with the control group, the dry weight of wheat roots inoculated with the functional bacterium TJ3-57 increased by 123.9% compared to the blank control.

[0135] When plants are stimulated, they produce a large amount of superoxide free radicals, causing membrane lipid peroxidation. Therefore, membrane lipid peroxidation is an important indicator of plant cell membrane damage. Malondialdehyde (MDA) is produced during the process of membrane lipid peroxidation, and its content can directly reflect the peroxidation level of the cytoplasmic membrane.

[0136] VIII. As Figure 12 shown, under salt stress conditions, the malondialdehyde content in plant leaves increased significantly. At two salt concentrations, the malondialdehyde content in wheat leaves treated with inoculation was significantly lower than that in the blank control treatment (CK) and the wheat malondialdehyde content under SQR9 treatment.

[0137] 1. At a salt concentration of 5‰, compared with the control group, the malondialdehyde (MDA) content in wheat inoculated with the functional bacterium TJ3-57 decreased by 35.4% compared to the blank control.

[0138] 2. At a salt concentration of 8‰, compared with the control group, the malondialdehyde (MDA) content in wheat inoculated with the functional bacterium TJ3-57 decreased by 41.7% compared to the blank control.

[0139] Example 4 16S phylogenetic identification of strain TJ3-57

[0140] I. Amplify and sequence the 16S rDNA sequence of strain TJ3-57. The sequencing results are shown in SEQ ID NO.1, specifically:

[0141] TGCAAGTCGAACGGCAGCACAGGAGAGCTTGCTCTCTGGGTGGCGAGTG

[0142] GCGGACGGGTGAGGAATACATCGGAATCTACTCTGTCGTGGGGGATAACGT

[0143] AGGGAAACTTACGCTAATACCGCATACGACCTACGGGTGAAAGCAGGGGA

[0144] TCTTCGGACCTTGCGCGATTGAATGAGCCGATGTCGGATTAGCTAGTTGGC

[0145] GGGGTAAAGGCCCACCAAGGCGACGATCCGTAGCTGGTCTGAGAGGATGA

[0146] TCAGCCACACTGGAACTGAGACACGGTCCAGACTCCTACGGGAGGCAGC

[0147] AGTGGGGAATATTGGACAATGGGCGCAAGCCTGATCCAGCCATACCGCGT

[0148] GGGTGAAGAAGGCCTTCGGGTTGTAAAGCCCTTTTGTTGGGAAAGAAATC

[0149] CAGCTGGCTAATACCCGGTTGGGATGACGGTACCCAAAGAATAAGCACCG

[0150] GCTAACTTCGTGCCAGCAGCCGCGGTAATACGAAGGGTGCAAGCGTTACT

[0151] CGGAATTACTGGGCGTAAAGCGTGCGTAGGTGGTTATTTAAGTCCGTTGTG

[0152] AAAGCCCTGGGCTCAACCTGGGAACTGCAGTGGATACTGGATGACTAGAA

[0153] TGTGGTAGAGGGTAGCGGAATTCCTGGTGTAGCAGTGAAATGCGTAGAGA

[0154] TCAGGAGGAACATCCATGGCGAAGGCAGCTACCTGGACCAACATTGACAC

[0155] TGAGGCACGAAAGCGTGGGGAGCAAACAGGATTAGATACCCTGGTAGTCC

[0156] ACGCCCTAAACGATGCGAACTGGATGTTGGGTGCAATTTGGCACGCAGTAT

[0157] CGAAGCTAACGCGTTAAGTTCGCCGCCTGGGGAGTACGGTCGCAAGACTG

[0158] AAACTCAAAGGAATTGACGGGGGCCCGCACAAGCGGTGGAGTATGTGGTT

[0159] TAATTCGATGCAACGCGAAGAACCTTACCTGGCCTTGACATGTCGAGAACT

[0160] TTCCAGAGATGGATTGGTGCCTTCGGGAACTCGAACACAGGTGCTGCATG

[0161] GCTGTCGTCAGCTCGTGTCGTGAGATGTTGGGTTAAGTCCCGCAACGAGC

[0162] GCAACCCTTGTCCTTAGTTGCCAGCACGTAATGGTGGGAACTCTAAGGAG

[0163] ACCGCCGGTGACAAACCGGAGGAAGGTGGGGATGACGTCAAGTCATCATG

[0164] GCCCTTACGGCCAGGGCTACACACGTACTACAATGGTAGGGACAGAGGGC

[0165] TGCAAGCCGGCGACGGTAAGCCAATCCCAGAAACCCTATCTCAGTCCGGA

[0166] TTGGAGTCTGCAACTCGACTCCATGAAGTCGGAATCGCTAGTAATCGCAGA

[0167] TCAGCATTGCTGCGGTGAATACGTTCCCGGGCCTTGTACACACCGCCCGTC

[0168] ACACCATGGGAGTTTGTTGCACCAGAAGCAGGTAGCTTAACCTTCGGGAGGGC。

[0169] II. The sequencing results were analyzed by BLAST alignment and a phylogenetic tree ( Figure 13 ) was constructed. Based on the name of the strain with relatively high homology to the strain to be tested, the species of the strain was preliminarily identified. Strain TJ3-57 belongs to Stenotrophomonas maltophilia, so it was named Stenotrophomonas maltophilia TJ3-57.

[0170] III. Deposition of Stenotrophomonas maltophilia TJ3-57

[0171] Stenotrophomonas maltophilia TJ3-57 provided by the present invention was deposited at the Guangdong Provincial Culture Collection of Microorganisms (abbreviation: CDMCC No. 64978; address: 5th Floor, Experimental Building, No. 100 Compound, Xianlie Middle Road, Yuexiu District, Guangzhou City, Guangdong Province) on May 8, 2024, and the deposit number is GDMCC NO. 64978.

[0172] Although the above embodiments have described the present invention in detail, they are only a part of the embodiments of the present invention, rather than all embodiments. People can also obtain other embodiments based on these embodiments without creative efforts, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A Stenotrophomonas maltophilia TJ3-57, characterized in that: The deposit number is GDMCC NO.64978.

2. A microbial agent, characterized in that: Including the Stenotrophomonas maltophilia TJ3-57 described in claim 1.

3. The microbial agent according to claim 2, characterized in that: The OD of Stenotrophomonas maltophilia TJ3-57 in the microbial agent 600 The value of is ≥1.

0.

4. A method for preparing the microbial agent according to claim 2 or 3, characterized in that: include: The Stenotrophomonas maltophilia TJ3-57 is cultured in a culture medium to obtain a microbial agent.

5. The preparation method according to claim 4, characterized in that: The culture temperature is 28-37° C.; the culture time is 24-36 hours; the culture is accompanied by rotation, and the rotation speed is 150-230 rpm.

6. Use of the Stenotrophomonas maltophilia TJ3-57 according to claim 1 in promoting plant growth and / or improving plant salt tolerance.

7. The use according to claim 6, characterized in that: The plants include wheat.

8. The use according to claim 6, characterized in that: The promoting of plant growth includes promoting the improvement of any one or more of the following indicators (1) to (6): (1) Plant height; (2) root length; (3) fresh weight of aboveground parts; (4) fresh root weight; (5) Aboveground dry weight; (6) Root dry weight.

9. The use according to claim 6, characterized in that: The improving the salt tolerance of plants includes alleviating the damage of salt stress to plants and / or improving the ability of plants to tolerate salt stress.

10. A method for improving the salt tolerance of plants, characterized in that: include: After the plants grow to the two-leaf and one-heart stage, the microbial agent comprising the Stenotrophomonas maltophilia TJ3-57 of claim 1 is applied.

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