Rhizosphere growth-promoting bacteria for enhancing salt tolerance of wheat and application thereof

Abstract

The application provides a rhizosphere growth promoting bacterium for enhancing salt tolerance of wheat and application thereof, and belongs to the technical field of agricultural microorganisms. The application provides a Stenotrophomonas maltophilia TJ3-57, and the preservation number is GDMCC NO.64978. 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 soil, and thus is favorable for improving the yield of crops in saline-alkali soil.

Description

Technical Field

[0001] This invention belongs to the field of agricultural microbial technology, specifically relating to a rhizosphere growth-promoting bacterium that enhances the salt tolerance of wheat and its application. Background Technology

[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 cultivation, adsorption fermentation, and processing. Microbial inoculants can be applied in various agricultural production processes, playing a significant role in soil improvement and fertility restoration. They can also control many pests and diseases, effectively improving crop quality and yield, thus achieving the goals of increasing production and protecting the ecological environment. Microbial inoculants exert their effects through interactions between microorganisms, between microorganisms and fertilizers, between microorganisms and plants, between microorganisms and soil, and between microorganisms and plants, as well as between microorganisms and soil. The use of microbial inoculants reduces the use of chemical fertilizers and pesticides in agricultural production and improves the quality of agricultural production. Significant progress has been made in the research and development of microbial inoculants in my country, achieving good results in water purification and waste treatment. Furthermore, some progress has been made in the efficient screening of beneficial bacteria. However, currently, there are no reports on Stenotrophomonas maltophilia improving saline-alkali soil and simultaneously enhancing the quality of agricultural production. Summary of the Invention

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

[0005] The objective of this invention is achieved through the following technical solution:

[0006] This invention provides a Stenotrophomonas maltophilia strain TJ3-57, with accession number GDMCC NO.64978.

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

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

[0009] This invention provides a method for preparing the microbial inoculant described in the above-mentioned technical solution, comprising:

[0010] The Stenotrophomonas maltophilia TJ3-57 was cultured in a culture medium to obtain a microbial inoculum.

[0011] Preferably, the culture temperature is 28–37°C; the culture time is 24–36 h; and the culture process is accompanied by rotation at a speed of 150–230 rpm.

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

[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 indicators (1) to (6):

[0015] (1) Plant height;

[0016] (2) Root length;

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

[0018] (4) Fresh weight of the root;

[0019] (5) Aboveground dry weight;

[0020] (6) Root and trunk weight.

[0021] Preferably, the improvement of plant salt tolerance includes mitigating the damage of salt stress to plants and / or improving the plant's ability to tolerate salt stress.

[0022] This invention provides a method for improving the salt tolerance of plants, comprising:

[0023] After the plant has grown to the two-leaf-one-heart stage, apply a microbial agent containing Stenotrophomonas maltophilia TJ3-57 as described in the above technical solution.

[0024] The beneficial effects of this invention are:

[0025] This invention provides a *Stenotrophomonas maltophilia* TJ3-57, with accession number GDMCC NO.64978. In this invention, *Stenotrophomonas maltophilia* TJ3-57 can improve the salt stress tolerance of plants, alleviate the damage caused by salt stress, promote the growth of plants in saline-alkali land, and thus help increase the yield of crops in saline-alkali land. The results of the embodiments of this invention show that *Stenotrophomonas maltophilia* TJ3-57 can promote the germination of wheat under salt stress, significantly increase the plant height, root length, aboveground fresh weight, root fresh weight, aboveground dry weight, and root dry weight of wheat under salt stress, and reduce malondialdehyde content, thereby promoting wheat growth under salt stress and alleviating the damage caused by salt stress. In summary, the *Stenotrophomonas maltophilia* TJ3-57 provided by this invention is beneficial for improving the salt stress tolerance of crops in saline-alkali land and for increasing the yield of crops in saline-alkali land.

[0026] Biological Preservation Instructions

[0027] Stenotrophomonas maltophilia TJ3-57 was deposited on May 8, 2024, at the Guangdong Provincial Center for Microbial Culture Collection, located at 5th Floor, Experimental Building, No. 100 Xianlie Middle Road, Yuexiu District, Guangzhou, Guangdong Province, with accession number GDMCC NO.64978. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a graph showing the statistical results of wheat germination rate under different salt concentrations in Example 2;

[0030] Figure 2 The figure shows the phenotypic results of the whole wheat plant of functional bacteria TJ3-57 and blank control group at a salt concentration of 5‰.

[0031] Figure 3 The figure shows the phenotypic results of functional bacteria TJ3-57 and blank control group wheat pots at a salt concentration of 5‰.

[0032] Figure 4 The figure shows the phenotypic results of the whole wheat plant of functional bacteria TJ3-57 and blank control group at a salt concentration of 8‰.

[0033] Figure 5 The figure shows the phenotypic results of functional bacteria TJ3-57 and blank control group wheat pots at a salt concentration of 8‰.

[0034] Figure 6 The graph shows the effects of five functional bacteria on wheat plant height.

[0035] Figure 7 The results of the effects of five functional bacteria on wheat root length are shown in the figure.

[0036] Figure 8 Figure 1 shows the effect of five functional bacteria on the fresh weight of wheat aboveground parts.

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

[0038] Figure 10 Figure showing the effects of five functional bacteria on the aboveground dry weight of wheat.

[0039] Figure 11 The effect of five functional bacteria on wheat root dry weight is shown in the figure.

[0040] Figure 12 The effect of five functional bacteria on the malondialdehyde content in wheat is shown in the figure.

[0041] Figure 13 Figure showing the phylogenetic analysis results of Stenotrophomonas maltophilia TJ3-57. Detailed Implementation

[0042] This invention provides a *Stenotrophomonas maltophilia* TJ3-57, with accession number GDMCC NO.64978. In this invention, the *Stenotrophomonas maltophilia* TJ3-57 is derived from the rhizosphere of the halophyte *Senecio scandens*. The nucleotide sequence of the 16S rDNA of the *Stenotrophomonas maltophilia* TJ3-57 is shown in SEQ ID NO.1. The *Stenotrophomonas maltophilia* TJ3-57 was deposited at the Guangdong Provincial Center for Microbial Culture Collection on May 8, 2024, with accession number GDMCC NO.64978.

[0043] This invention provides a microbial inoculant comprising Stenotrophomonas maltophilia TJ3-57 as described in the above-mentioned technical solution. As an optional embodiment of this invention, the OD of Stenotrophomonas maltophilia TJ3-57 in the microbial inoculant is... 600 The value is ≥1.0, and can be 1.0.

[0044] This invention provides a method for preparing the microbial inoculant described in the above-mentioned technical solution, comprising:

[0045] The Stenotrophomonas maltophilia TJ3-57 was cultured in a culture medium to obtain a microbial inoculum.

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

[0047] After cultivation, the present invention obtains a culture medium of Stenotrophomonas maltophilia TJ3-57. As an optional embodiment of the present invention, the Stenotrophomonas maltophilia TJ3-57 culture medium can be used directly as a microbial inoculum; alternatively, the bacterial cells in the Stenotrophomonas maltophilia TJ3-57 culture medium can be isolated and resuspended to obtain a bacterial suspension for use as a microbial inoculum. The present invention does not specifically limit the isolation method; any conventional method in the art can be used. As an optional embodiment of the present invention, the isolation method can be centrifugation. After the bacterial cells are isolated, they are resuspended in sterile water to obtain a bacterial suspension. As an optional embodiment of the present invention, the OD of Stenotrophomonas maltophilia TJ3-57 in the bacterial suspension... 600 The value can be ≥1.0 or 1.0.

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

[0049] This invention provides a method for improving the salt tolerance of plants, comprising:

[0050] After the plant has grown to the two-leaf-one-heart stage, a microbial inoculant containing *Stenotrophomonas maltophilia* TJ3-57 as described in the above-mentioned technical solution is applied. As an optional embodiment of the present invention, the application can be performed within 1-2 weeks of the plant reaching the two-leaf-one-heart stage. As an optional embodiment of the present invention, the application can be performed twice; the interval between the two applications is two weeks; and the dosage of *Stenotrophomonas maltophilia* TJ3-57 used in each application is 10... 7 CFU / g soil, meaning 10 CFU is applied per gram of soil. 7 Stenotrophomonas maltophilia TJ3-57 (CFU).

[0051] To further illustrate the present invention, the technical solutions provided by the present invention will be described in detail below with reference to the accompanying drawings and embodiments, but these should not be construed as limiting the scope of protection of the present invention.

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

[0053] Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Unless otherwise specified, the experimental materials used in the following examples were all purchased from conventional biochemical reagent stores. All quantitative experiments in the following examples were performed in triplicate, and the results were averaged.

[0054] Example 1: Construction of a microbial strain resource bank

[0055] Halophytic materials: Suaeda salsa, Sesbania sesquiterpene, and Tamarix chinensis were collected from a farm near the Chinese Milu Deer Park in Dafeng District, Yancheng City (32°59′46″N, 120°49′48″E); Spartina alterniflora, a halophyte, was collected from the mudflats near the Yellow Sea National Forest Park in Dafeng District, Yancheng City (32°52′25″N, 120°54′24″E).

[0056] Using a macro-culturation approach, rhizosphere samples of halophytes were subjected to extreme dilutions with PBS-S, with a dilution gradient of 10-1. -6 10 -7 Rhizosphere sample suspensions were cultured in TSB liquid medium in 96-well plates. After 14 days of culture, 96-well plates with a microbial growth probability of 30%–50% were selected. Under aseptic conditions, 80 μL of bacterial culture was aspirated from the wells containing growing microorganisms and added to a PCR tube containing 80 μL of 40% glycerol (a 40% glycerol aqueous solution by volume). The mixture was gently blown and aspirated, labeled, and stored at -80°C to preserve the microbial strain, thus obtaining a halophyte rhizosphere microbial strain resource bank.

[0057] Experimental results: 3991 effective mycelial pores were isolated from the rhizosphere of four halophytes: Sesbania, Suaeda salsa, Spartina alterniflora and Tamarix chinensis.

[0058] Example 2 Screening of functional strains

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

[0060] 1. Select plump wheat seeds of uniform size and disinfect their surface.

[0061] Soak the seeds in a 75% ethanol aqueous solution for 1 minute, then rinse off the ethanol on the seed surface with sterile water. Next, soak the seeds in a 2% sodium hypochlorite aqueous solution for 5 minutes, and rinse them 6 times with sterile water.

[0062] 2. After surface disinfection in step 1, wheat seeds were soaked in sterile sodium chloride solutions of different salt concentrations (0mM, 40mM, 80mM, 120mM, 160mM, 200mM, 240mM), with three replicates for each treatment and 10 seeds per replicate. The seeds were soaked at 25°C in the dark for 4 hours.

[0063] 3. Place the seeds soaked in step 2 into a petri dish containing sterile moistened filter paper with the appropriate salt concentration, and place it in a 25℃ light incubator for germination, with a day / night ratio of 16h / 8h for 7 days.

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

[0065] Experimental results: Based on the statistical results of wheat germination rate under different salt concentrations ( Figure 1 ), and determined 200 mM as the critical salt stress concentration for wheat germination.

[0066] II. Screening of Mycelial Wells

[0067] Test strains: 3991 effective wells isolated in Example 1.

[0068] 1. After surface disinfection, wheat seeds were soaked in a 240mM sodium chloride solution at 25°C in the dark for 4 hours. The control group was soaked in sterile water.

[0069] 2. Place the seeds soaked in step 1 in a petri dish containing sterile water and 240mM sodium chloride solution and lined with filter paper, with 3 seeds per petri dish and three replicates.

[0070] 3. Take 10 μL of bacterial culture from each PCR tube of the halophyte strain resource bank constructed in Example 1 and transfer it to a 2 mL centrifuge tube containing 1 mL of TSB liquid medium. Gently mix and incubate at 30°C and 170 rpm in a shaker until OD reaches the target value. 600 =1.0.

[0071] 4. In step 2, add 100 μL of the corresponding bacterial solution from step 3 directly above each wheat seed. That is, add the bacterial solution obtained from step 3 to one effective well directly above each wheat seed. Number the wells and place them in a 25℃ light incubator for germination. The day / night ratio is 16h / 8h for 4 days.

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

[0073] A positive control was obtained by treating with Bacillus amyloliquefaciens SQR9 (accession number CGMCC NO.5808, disclosed in ZL201710797445.0), a negative control was obtained by adding only salt and no bacteria, and a control was obtained by neither adding salt nor bacteria.

[0074] Experimental results: Based on the statistical results of the germination rate of wheat after inoculation with different mycelium wells at a salt concentration of 240mM, 33 mycelium wells that can promote wheat germination under salt stress were screened out.

[0075] III. Purification of the bacterial strain

[0076] Based on the initial screening results of the germination test under salt stress, the mycelial wells that can promote wheat germination under 240mM salt stress were identified and isolated and purified as single bacteria.

[0077] 1. Spread the bacterial culture from the wells obtained from the initial screening onto a TSB plate and incubate upside down at 30°C for 24 hours.

[0078] 2. Select individual colonies that grow rapidly and have different morphologies from step 1, and continue to streak the remaining colonies that have not yet appeared on TSB plates until individual colonies appear.

[0079] 3. Then, each single colony from step 2 is purified three times by streaking on TSB plates.

[0080] 4. Pick a single colony from step 3 into a test tube containing 3 mL of TSB liquid culture medium, and shake at 30°C and 170 rpm until the culture becomes turbid.

[0081] 5. Take 80 μL of the bacterial culture from step 4 into a tube containing 40% glycerol aqueous solution and store at -80°C.

[0082] Based on the preliminary screening results of crop germination experiments under salt stress, a single-strain resource bank was constructed.

[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] Example 3: Pot culture verification of functional strains

[0085] Test strains: the 5 strains screened in Example 2 and Bacillus amyloliquefaciens SQR9.

[0086] Soil materials used in the test: 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 was 7.84, and the pH of the 8‰ saline-alkali soil was 7.80.

[0087] I. Preparation of bacterial suspension

[0088] 1. The five functional strains obtained from screening and the control strain SQR9 (Bacillus amyloliquefaciens SQR9) were inoculated into TSB liquid medium and cultured at 30°C and 170 rpm.

[0089] 2. After 24 hours, the bacterial suspension was centrifuged, and then the bacterial suspension was resuspended in sterile water to adjust the OD of the bacterial suspension. 600 The value is 1.0.

[0090] II. Germination and Seedling Raising of Wheat Seeds

[0091] 1. First, the surface of the wheat seeds needs to be sterilized. This step is carried out in a clean bench. Select plump and uniformly sized Bainong Aikang 58 wheat seeds, disinfect the wheat seeds with a 75% ethanol solution for 1 minute, then soak the wheat seeds in a 2% sodium hypochlorite solution for 5 minutes, and rinse them 6 times with sterile ultrapure water to remove the sodium hypochlorite solution adhering 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 wheat seedlings with uniform growth from step 2 and transplant them into a seedling substrate for seedling cultivation. When the wheat grows to the two-leaf-one-heart stage, select wheat seedlings with uniform growth and transplant them into designated soil for subsequent experiments.

[0094] III. Pot Experiment Design

[0095] This experiment was conducted in the greenhouse of Baima Research Base of Nanjing Agricultural University in Nanjing, Jiangsu Province, from November 2023 to January 2024, with an experimental period of 28 days.

[0096] Two salinity gradients were set up in this experiment: 5‰ and 8‰. Each pot was loaded with 500g of soil. The experiment set up a control group and a treatment group. The control group pots were either uninoculated (blank control group) or inoculated with SQR9 (positive control group). The treatment groups were inoculated with 5 functional strains.

[0097] 1. Select wheat seedlings with uniform growth from step two and transplant them into saline soils with two salinity gradients (5‰ and 8‰). Each pot contains 5 wheat seedlings, and each treatment has 3 control pots. Incubate at room temperature and water appropriately to maintain soil moisture content.

[0098] 2. One week after wheat transplanting, the seedling roots were irrigated with bacterial suspensions of five functional bacteria and SQR9, maintaining an inoculation concentration of 10 for each bacteria. 7 CFU / g soil, meaning 10 CFU is applied per gram of soil. 7 CFU bacteria. The specific steps are as follows: one type of bacteria is inoculated into one wheat treatment group, the blank control group is not inoculated, and an equal volume of sterile water as the bacterial suspension is added. The positive control group is inoculated with Bacillus amyloliquefaciens SQR9.

[0099] 3. Two weeks later, the bacterial suspension was added again in the same manner, while the control group was watered with the same volume of sterile water per pot. The plants were then cultured at 30℃ under 16 / 8h light conditions for another two weeks.

[0100] 4. After completing step 3, measure various physiological and biochemical indicators of wheat plants.

[0101] The malondialdehyde (MDA) content was detected using a commercially available reagent kit (purchased from Nanjing Jiancheng Biotechnology Co., Ltd.).

[0102] The results of various physiological and biochemical index measurements of wheat plants are shown in Tables 1-2 and 2. Figures 2-12 As shown.

[0103] Figure 2 The results show the phenotypic observation of whole wheat plants treated with functional bacteria TJ3-57 and blank control group at a salt concentration of 5‰. The three plants on the left are the blank control group, and the three plants on the right are the functional bacteria TJ3-57 treatment group. Figure 3 The results show the phenotypic observations of wheat pot plants with functional bacteria TJ3-57 and blank control group at a salt concentration of 5‰. The two pots on the left are blank control group; the two pots on the right are functional bacteria TJ3-57 treatment group. Figure 4 The results show the phenotypic observation of whole wheat plants treated with functional bacteria TJ3-57 and blank control group at a salt concentration of 8‰. The two plants on the left are the blank control group, and the two plants on the right are the functional bacteria TJ3-57 treatment group. Figure 5 The results show the phenotypic observations of wheat pot plants with functional bacteria TJ3-57 and blank control group at a salt concentration of 8‰. The two pots on the left are blank control group, and the two pots on the right are functional bacteria TJ3-57 treatment group.

[0104] Figure 6 The graph shows the effects of five functional bacteria on wheat plant height. In the graph, A shows the effects of the five functional bacteria on wheat plant height at a salt concentration of 5‰; B shows the effects of the five functional bacteria on wheat plant height at a salt concentration of 8‰.

[0105] Figure 7 The graph shows the effects of five functional bacteria on wheat root length. In the graph, A shows the effects of the five functional bacteria on wheat root length at a salt concentration of 5‰; B shows the effects of the five functional bacteria on wheat root length at a salt concentration of 8‰.

[0106] Figure 8 The figure shows the effects of five functional bacteria on the fresh weight of wheat aboveground parts; where A represents the effects of the five functional bacteria on the fresh weight of wheat aboveground parts at a salt concentration of 5‰; and B represents the effects of the five functional bacteria on the fresh weight of wheat aboveground parts at a salt concentration of 8‰.

[0107] Figure 9 The figure shows the effect of five functional bacteria on the fresh weight of wheat roots. In the figure, A shows the effect of the five functional bacteria on the fresh weight of wheat roots at a salt concentration of 5‰; B shows the effect of the five functional bacteria on the fresh weight of wheat roots at a salt concentration of 8‰.

[0108] Figure 10 The graph shows the effects of five functional bacteria on the aboveground dry weight of wheat. In the graph, A shows the effects of the five functional bacteria on the aboveground dry weight of wheat at a salt concentration of 5‰; B shows the effects of the five functional bacteria on the aboveground dry weight of wheat at a salt concentration of 8‰.

[0109] Figure 11 The graph shows the effects of five functional bacteria on wheat root dry weight. In the graph, A shows the effects of the five functional bacteria on wheat root dry weight at a salt concentration of 5‰; B shows the effects of the five functional bacteria on wheat root dry weight at a salt concentration of 8‰.

[0110] Figure 12 The graph shows the effects of five functional bacteria on the malondialdehyde (MDA) content of wheat. In the graph, A shows the effect of the five functional bacteria on the MDA content of wheat at a salt concentration of 5‰; B shows the effect of the five functional bacteria on the MDA content of wheat at a salt concentration of 8‰.

[0111] Table 1. Results of various physiological and biochemical indicators of wheat plants in each treatment group at a salt concentration of 15‰ (mean values).

[0112]

[0113] Table 28‰ salt concentration: Detection results (mean values) of various physiological and biochemical indicators of wheat plants in each treatment group.

[0114]

[0115] From Tables 1-2 and Figures 2-12 The experimental results are as follows:

[0116] I. For example Figures 2-5 As shown, wheat growth and development are severely inhibited under salt stress. At a salt concentration of 5‰, wheat growth essentially stops, but inoculation with the functional bacterium TJ3-57 helps wheat recover. At a salt concentration of 8‰, wheat growth is severely inhibited, with leaves turning yellow and curling; inoculation with the functional bacterium TJ3-57 helps wheat survive.

[0117] II. Figure 6 As shown, with increasing salt concentration, the wheat plant height under high salt stress (8‰) was significantly lower than that under low salt stress (5‰). At both salt concentrations, the wheat seedlings treated with the inoculum were significantly taller than those under the blank control (CK) and SQR9 treatments.

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

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

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

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

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

[0123] IV. Figure 8 As shown, with increasing salt concentration, the aboveground fresh weight of wheat under high salt stress (8‰) was significantly lower than that under low salt stress (5‰). At both salt concentrations, the aboveground fresh weight of wheat seedlings treated with the inoculum was significantly higher than that of wheat seedlings treated with the blank control (CK) and SQR9.

[0124] 1. At a salt concentration of 5‰, compared with the control group, the fresh weight of wheat aboveground parts inoculated with functional bacteria TJ3-57 increased by 119.2%.

[0125] 2. At a salt concentration of 8‰, compared with the control group, the fresh weight of wheat aboveground parts inoculated with functional bacteria TJ3-57 increased by 81.3%.

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

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

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

[0129] VI. For example Figure 10 As shown, with increasing salt concentration, the aboveground dry weight of wheat under high salt stress (8‰) was significantly lower than that under low salt stress (5‰). At both salt concentrations, the aboveground dry weight of wheat seedlings treated with the inoculum was significantly higher than that of wheat seedlings treated with the blank control (CK) and SQR9.

[0130] 1. At a salt concentration of 5‰, compared with the control group, the aboveground dry weight of wheat inoculated with functional bacteria TJ3-57 increased by 61.0%.

[0131] 2. At a salt concentration of 8‰, compared with the control group, the aboveground dry weight of wheat inoculated with functional bacteria TJ3-57 increased by 46.8%.

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

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

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

[0135] When plants are stimulated, they produce a large number of superoxide free radicals, leading to membrane lipid peroxidation. Therefore, membrane lipid peroxidation is an important indicator of plant cell membrane damage. The process of membrane lipid peroxidation produces malondialdehyde (MDA), the content of which can directly reflect the peroxidation level of the cell membrane.

[0136] 8. For example Figure 12 As shown, under salt stress, the malondialdehyde (MDA) content in plant leaves increased significantly. At both salt concentrations, the MDA content in wheat leaves treated with the inoculum was significantly lower than that in wheat leaves treated with the blank control (CK) and SQR9.

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

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

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

[0140] 1. The 16S rDNA sequence of strain TJ3-57 was amplified and sequenced. 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] GCAACCTTGTCCTTAGTTGCCAGCACGTAATGGTGGGAACTCTAAGGAG

[0163] ACCGCCGGTGACAAACCGGAGGAAGGTGGGGATGACGTCAAGTCATCATG

[0164] GCCCTTACGGCCAGGGCTACACACGTACTACAATGGTAGGGACAGAGGGC

[0165] TGCAAGCCGGCGACGGTAAGCCAATCCCAGAAACCCTATCTCAGTCCGGA

[0166] TTGGAGTCTGCAACTCGACTCCATGAAGTCGGAATCGCTAGTAATCGCAGA

[0167] TCAGCATTGCTGCGGTGAATACGTTCCCGGGCCTTGTACACACCGCCCGTC

[0168] ACACCATGGGAGTTTGTTGCACCAGAAGCAGGTAGCTTAACCTTCGGGAGGGC.

[0169] II. The sequencing results were analyzed using BLAST to construct a phylogenetic tree. Figure 13 Based on the name of the strain with high homology to the test strain, the species of the strain was preliminarily identified. Strain TJ3-57 belongs to Stenotrophomonas maltophilia, therefore it was named Stenotrophomonas maltophilia TJ3-57.

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

[0171] The Stenotrophomonas maltophilia TJ3-57 provided by this invention was deposited on May 8, 2024 at the Guangdong Provincial Center for Microbial Culture Collection (CDMCC No. 64978; Address: 5th Floor, Experimental Building, No. 100 Xianlie Middle Road, Yuexiu District, Guangzhou, Guangdong Province), with accession number GDMCC NO. 64978.

[0172] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. People can obtain other embodiments based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A type of Stenotrophomonas maltophilia ( Stenotrophomonas maltophilia TJ3-57, characterized in that, The accession number is GDMCC NO: 64978.

2. A microbial inoculant, characterized in that, Includes Stenotrophomonas maltophilia TJ3-57 as described in claim 1.

3. The microbial agent according to claim 2, characterized in that, The OD600 value of Stenotrophomonas maltophilia TJ3-57 in the microbial inoculant is ≥1.

0.

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

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

6. The application of Stenotrophomonas maltophilia TJ3-57 as described in claim 1 in promoting wheat growth and improving wheat salt tolerance; wherein the salt tolerance includes a salt tolerance of 5‰ to 8‰.

7. The application according to claim 6, characterized in that, The promotion of wheat growth includes promoting the improvement of one or more of the following indicators (1) to (6): (1) Plant height; (2) Root length; (3) Fresh weight of the above-ground parts; (4) Fresh weight of the root; (5) Aboveground dry weight; (6) Root and trunk weight.

8. The application according to claim 6, characterized in that, Improving wheat salt tolerance includes mitigating the damage of salt stress to plants and / or enhancing the plant's ability to tolerate salt stress.

9. A method for improving the salt tolerance of wheat, characterized in that, include: After the wheat has grown to the two-leaf and one-heart stage, apply a microbial agent containing Stenotrophomonas maltophilia TJ3-57 as described in claim 1.

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