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

Abstract

The invention provides a growth-promoting rhizobacteria for enhancing salt tolerance of corn and application of the growth-promoting rhizobacteria, and belongs to the technical field of agricultural microorganisms. The invention provides a pseudomonas bacterium TJ1-185, and the preservation number of the pseudomonas bacterium TJ1-185 is CDMCC (China Description of Microbiological Culture Collection Center) No.64979. The pseudomonas bacteria TJ1-185 can improve the salt stress resistance of plants and relieve the damage of salt stress to the plants. The result of the embodiment shows that the pseudomonas bacterium TJ1-185 can promote corn to germinate under salt stress, improve the plant height, root length, overground part fresh weight, root fresh weight, overground part dry weight and root dry weight of corn under the salt stress condition, and reduce the malondialdehyde content, thereby promoting the growth of corn under the salt stress condition and improving the salt stress resistance of corn. The damage of salt stress to the corn is relieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of agricultural microorganisms, and particularly relates to a rhizosphere growth-promoting bacterium for enhancing the salt tolerance of maize and its application. Background Art

[0002] Soil salinization refers to the phenomenon that the water containing salt at the bottom layer of the soil rises to the surface under the action of soil capillary force, and after the water volatilizes, soluble salts precipitate and accumulate on the soil surface. Soil salinization can be divided into natural salinization and secondary salinization according to its causes. The former is mainly distributed around salt lakes, and the latter is mainly distributed in the low-lying areas of the terraces along rivers, lakes and coasts. The causes of soil salinization are divided into natural factors and human factors. Natural factors mainly refer to the accumulation of soluble salts in the soil on the soil surface after circulating in nature, mainly including climate change, topography and geology, and hydrological conditions, etc. Human factors mainly include overcutting, unreasonable irrigation, and large-scale reclamation, etc. Soil salinization is a common problem worldwide. Soil salinization will have an adverse impact on the physical and chemical properties of the soil. High concentrations of salts will lead to the deterioration of soil structure, such as swelling, disintegration, dispersion, hardening and surface crusting, etc., resulting in a decrease in hydraulic conductivity, water infiltration capacity and porosity; too high salinity will also lead to an increase in soil pH, loss of organic matter, inhibition of nutrient cycling, and toxicity of some main anions / cations in the soil. Soils affected by salinization often show nutrient deficiencies (mainly N, P, K) and a decrease in the availability of micronutrients (such as Al, Fe, Zn, Cu, Mn), ultimately leading to a decrease in soil fertility. Soil salinization will also cause salt stress to plants and affect crop growth. When the soil salt content is too high, the large uptake of salts by plants will inhibit the physiological metabolism process of plants, and even affect the survival of plants. High-concentration salt stress will also have an adverse impact on the physiological processes of plants, such as ion homeostasis, lipid metabolism, photosynthesis and protein synthesis. For agricultural production, soil salinization will affect the growth and development of crops and reduce the quality of agricultural products. Therefore, soil salinization is an important factor limiting agricultural production.

[0003] In recent years, some progress has been made in alleviating plant salt stress by exogenous addition of microorganisms, and it has gradually developed into a new method for alleviating salt stress. Existing experiments have shown that inoculating arbuscular mycorrhizae (AM) can improve the resistance of plants to salt stress. Arbuscular mycorrhizae improve the salt tolerance of maize, mung bean and clover by improving osmotic adjustment or the accumulation of proline. Currently, there is no reported Pseudomonas bacterium that can be used to alleviate soil salinization and promote plant growth. Summary of the Invention

[0004] Aiming at the defects in the prior art, the purpose of the present invention is to provide a Pseudomonas bacterium, which can improve the salt stress tolerance of saline-alkali land crops, promote the growth of saline-alkali land crops, and increase the yield of crops on saline-alkali land.

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

[0006] The present invention provides a Pseudomonas bacterium (Pseudomonas sp.) TJ1-185, with a preservation number of CDMCC No. 64979.

[0007] The present invention provides a bacterial agent, which includes the Pseudomonas bacterium TJ1-185 described in the above technical solution.

[0008] Preferably, the OD 600 value of the Pseudomonas bacterium TJ1-185 in the bacterial agent is ≥1.0.

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

[0010] Culturing the Pseudomonas bacterium TJ1-185 in a culture medium to obtain the bacterial agent.

[0011] Preferably, the temperature of the culturing is 30-37°C; the time of the culturing is 18-30 h; the rotation speed of the culturing is 150-250 rpm.

[0012] The present invention provides the application of the Pseudomonas bacterium TJ1-185 described in the above technical solution, the bacterial agent described in the above technical solution, or the bacterial agent prepared by the preparation method described in the above technical solution in promoting plant growth and / or improving plant salt tolerance.

[0013] Preferably, the plant includes corn.

[0014] Preferably, the promotion of plant growth includes any one or more of increasing plant plant height, increasing plant root length, increasing plant aboveground fresh weight, increasing plant root fresh weight, increasing plant aboveground dry weight, and increasing plant root dry weight.

[0015] Preferably, the improvement of plant salt tolerance includes alleviating the damage of salt stress to plants and / or improving the salt stress tolerance of plants.

[0016] The present invention provides a method for improving the salt stress tolerance of plants, including:

[0017] Applying a bacterial agent including the Pseudomonas bacterium TJ1-185 described in the above technical solution during the growth process of plants.

[0018] Beneficial effects:

[0019] The present invention provides a bacterium of the genus Pseudomonas (Pseudomonas sp.) TJ1-185, with the preservation number of CDMCC No. 64979. The bacterium of the genus Pseudomonas TJ1-185 provided by the present invention can improve the salt stress tolerance of plants, alleviate the damage of salt stress to plants, promote the growth of crops in saline-alkali land, and increase the yield of crops on saline-alkali land. The results of the examples of the present invention show that the bacterium of the genus Pseudomonas TJ1-185 can promote the germination of maize under salt stress, increase the plant height, root length, aboveground fresh weight, root fresh weight, aboveground dry weight and root dry weight of maize under salt stress conditions. At the same time, it can also reduce the content of malondialdehyde, thereby promoting the growth of maize under salt stress conditions and alleviating the damage of salt stress to maize.

[0020] Biological deposit description

[0021] The bacterium of the genus Pseudomonas TJ1-185, classified and named as Pseudomonas sp., was deposited at 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 City, Guangdong Province, and the preservation number is GDMCC NO. 64979. Description of the drawings

[0022] 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 to be used 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.

[0023] Figure 1 It is a statistical result graph of the germination rate of maize at different salt concentrations;

[0024] Figure 2 It is a phenotypic observation result graph of the whole maize plants of the functional bacterium TJ1-185 and the blank control group under the salt concentration of 5‰;

[0025] Figure 3 It is a phenotypic observation result graph of the maize potted plants of the functional bacterium TJ1-185 and the blank control group under the salt concentration of 5‰;

[0026] Figure 4 It is a phenotypic observation result graph of the whole maize plants of the functional bacterium TJ1-185 and the blank control group under the salt concentration of 8‰;

[0027] Figure 5 It is a phenotypic observation result graph of the maize potted plants of the functional bacterium TJ1-185 and the blank control group under the salt concentration of 8‰;

[0028] Figure 6Effect diagram of five functional bacteria on the plant height of maize;

[0029] Figure 7 Effect diagram of five functional bacteria on the root length of maize;

[0030] Figure 8 Effect diagram of five functional bacteria on the fresh weight of the aboveground part of maize;

[0031] Figure 9 Effect diagram of five functional bacteria on the fresh weight of maize roots;

[0032] Figure 10 Effect diagram of five functional bacteria on the dry weight of the aboveground part of maize;

[0033] Figure 11 Effect diagram of five functional bacteria on the dry weight of maize roots;

[0034] Figure 12 Effect diagram of five functional bacteria on the MDA content of maize;

[0035] Figure 13 Phylogenetic analysis result diagram of Pseudomonas sp. TJ1-185. Detailed implementation manners

[0036] The present invention provides a Pseudomonas sp. TJ1-185 with a preservation number of CDMCC No. 64979. In the present invention, the Pseudomonas sp. TJ1-185 is derived from the rhizosphere of the halophyte Sesbania cannabina. In the present invention, the nucleotide sequence of the 16S rDNA of the Pseudomonas sp. TJ1-185 is as shown in SEQ ID NO.1. In the present invention, the Pseudomonas sp. TJ1-185 was deposited at the Guangdong Provincial Culture Collection of Microorganisms on May 8, 2024, with a preservation number of GDMCC NO. 64979.

[0037] The present invention provides a bacterial agent comprising the Pseudomonas sp. TJ1-185 described in the above technical solution. As an optional implementation manner of the present invention, the OD 600 value of the Pseudomonas sp. TJ1-185 in the bacterial agent is ≥1.0, or can also be 1.0.

[0038] The present invention provides a preparation method of the bacterial agent described in the above technical solution, including:

[0039] Culturing the Pseudomonas sp. TJ1-185 in a culture medium to obtain a bacterial agent.

[0040] As an alternative embodiment of the present invention, the culture medium comprises TSB liquid medium; the culture temperature can be 30-37°C, or can be 30, 31, 32, 33, 34, 35, 36 or 37°C; the culture time can be 18-30 h, or can be 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29 or 30 h; the rotation speed during the culture process can be 150-250 rpm, or can be 150, 160, 170, 180, 190, 200, 210, 220, 230, 240 or 250 rpm.

[0041] After the culture is completed, a Pseudomonas bacterium TJ1-185 culture solution is obtained. As an alternative embodiment of the present invention, the Pseudomonas bacterium TJ1-185 culture solution can be directly used as a microbial agent, or the cells in the Pseudomonas bacterium TJ1-185 culture solution can be separated and resuspended to obtain a cell suspension as a microbial agent for application. The present invention has no special limitation on the separation method, and conventional methods in the art can be used. As an alternative 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 alternative embodiment of the present invention, the OD 600 value of Pseudomonas bacterium TJ1-185 in the cell suspension ≥ 1.0, or can be 1.0.

[0042] The present invention provides the application of the Pseudomonas bacterium TJ1-185 described in the above technical solution, the microbial agent described in the above technical solution, or the microbial agent prepared by the preparation method described in the above technical solution in promoting plant growth and / or improving the salt tolerance ability of plants. As an alternative embodiment of the present invention, the plants include corn. As an alternative embodiment of the present invention, the promotion of plant growth includes any one or more of increasing plant height, increasing plant root length, increasing the fresh weight of the above-ground part of the plant, increasing the fresh weight of the roots of the plant, increasing the dry weight of the above-ground part of the plant, and increasing the dry weight of the roots of the plant. As an alternative embodiment of the present invention, the improvement of the salt tolerance ability of plants includes alleviating the damage of salt stress to plants and / or improving the salt stress tolerance ability of plants. The results of the examples of the present invention show that the Pseudomonas bacterium TJ1-185 can promote the growth of corn under salt concentration stress conditions of 5‰ and 8‰, and increase the plant height, root length, fresh weight of the above-ground part, fresh weight of the roots, dry weight of the above-ground part and fresh weight of the roots of corn. Further, the Pseudomonas bacterium TJ1-185 can also significantly reduce the malondialdehyde content of corn under salt stress conditions, and thus is beneficial to improving the salt stress tolerance ability of corn.

[0043] The present invention provides a method for improving the salt stress tolerance ability of plants, comprising:

[0044] During the growth process of plants, a bacterial agent including the Pseudomonas bacterium TJ1-185 described in the above technical solution is applied.

[0045] As an alternative embodiment of the present invention, the application timing of the bacterial agent can be when seeds are planted, or can be after the plants grow to the two-leaf and one-heart stage. When the bacterial agent including the Pseudomonas bacterium TJ1-185 is applied after the plants grow to the two-leaf and one-heart stage in the present invention, the application timing can be within 1-2 weeks after the plants grow to the two-leaf and one-heart stage. As an alternative embodiment 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 the Pseudomonas bacterium TJ1-185 each time is 10 7 CFU / g soil, that is, 10 7 CFU of the Pseudomonas bacterium TJ1-185 is applied to each gram of soil.

[0046] As an alternative embodiment of the present invention, the Pseudomonas bacterium TJ1-185 can also be mixed and fermented with a solid and then mixed with organic fertilizer and applied to the soil.

[0047] To further illustrate the present invention, the technical solutions 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.

[0048] The experimental methods in the following embodiments are all conventional methods unless otherwise specified. The test materials used in the following embodiments are all obtained from conventional biochemical reagent stores unless otherwise specified. In the following embodiments, all quantitative tests are set with three repeated experiments, and the results are averaged.

[0049] The corn variety used in the following embodiments is: Zhengdan 958.

[0050] Example 1 Construction of a strain resource library

[0051] 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 Huanghai National Forest Park in Dafeng District, Yancheng City (32°52′25″ N, 120°54′24″ E)

[0052] Using the method of metacultivationomics, the rhizosphere samples of halophytes are serially diluted with a buffer (PBS-S), and the dilution gradients of 10 -6 、10 -7The rhizosphere sample suspension was cultured in TSB liquid medium in a 96-well plate. After 14 days of culture, 96-well plates with a microbial growth probability of 30%-50% were selected. In a sterile environment, 80 μL of the bacterial liquid was aspirated from the wells with growing microorganisms and added to a pcr tube containing 80 μL of 40% glycerol (an aqueous glycerol solution with a glycerol volume fraction of 40%). It was gently pipetted and mixed well, marked, and placed in a -80 °C refrigerator for strain preservation, thus obtaining a salt-tolerant rhizosphere strain resource library.

[0053] Experimental results: 3991 effective bacterial wells were isolated from the rhizospheres of four halophytes, Sesbania cannabina, Suaeda glauca, Spartina alterniflora, and Tamarix chinensis.

[0054] Example 2 Screening of functional strains

[0055] I. Determination of the critical salt concentration for maize seed germination

[0056] 1. Select plump maize seeds of uniform size for surface disinfection.

[0057] After soaking in an aqueous ethanol solution with an ethanol volume fraction of 75% for 1 minute, the ethanol on the seed surface was rinsed off with sterile water. Then, it was soaked in a sodium hypochlorite solution with a mass concentration of 2% for 10 min and rinsed 6 times with sterile water.

[0058] 2. The surface-disinfected maize seeds in step 1 were respectively soaked in sterile sodium chloride solutions with different salt concentrations (0 mM, 40 mM, 80 mM, 120 mM, 160 mM, 200 mM, 240 mM, 280 mM). There were three replicates for each treatment, and 10 seeds for each replicate. They were soaked in the dark at 25 °C for 4 h.

[0059] 3. The seeds soaked in step 2 were placed in a petri dish containing sterile wet filter paper with the corresponding salt concentration and germinated in a 25 °C light incubator with a day-night ratio of 16 h / 8 h for 7 days.

[0060] 4. After completing step 3, the germination rate of maize seeds in different treatments was statistically analyzed (germination rate (%) = (number of normally germinated seeds on the 7th day of germination / number of tested seeds) × 100), and the critical salt concentration for maize seed germination was found.

[0061] Experimental results: According to the statistical results of the germination rate of maize at different salt concentrations ( Figure 1 ), 240 mM was determined as the critical salt stress concentration for maize germination.

[0062] II. Screening of bacterial wells

[0063] Test strains: 3991 effective bacterial wells isolated in Example 1.

[0064] 1. Place the surface-sterilized corn seeds in a 240 mM sodium chloride solution and soak them in the dark at 25 °C for 4 hours. The control group is soaked with sterile water.

[0065] 2. Place the soaked seeds from step 1 in a petri dish containing sterile water and 240 mM sodium chloride solution and lined with filter paper for cultivation. Each petri dish contains 3 seeds, with three replicates.

[0066] 3. Pipette 10 μL of the bacterial solution from each PCR tube in the halophyte bacterial strain resource library constructed in Example 1 into a 2 mL centrifuge tube containing 1 mL of TSB liquid medium, gently swirl to mix, and culture it in a shaker at 30 °C and 170 rpm until OD 600 = 1.0.

[0067] 4. Drop 100 μL of the corresponding bacterial solution from step 3 directly above each treated corn seed in step 2, that is, add a valid bacterial pore corresponding to the bacterial solution obtained through the above step 3 directly above each treated corn seed, 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.

[0068] 5. Observe the germination of different treatments in step 4, and preliminarily screen out the bacterial pores that can promote the germination of corn under salt stress.

[0069] Use Bacillus amyloliquefaciens SQR9 (the preservation number is CGMCC NO.5808, which has been disclosed in ZL201710797445.0) treatment as the positive control, only adding salt without adding bacteria treatment as the negative control, and not adding salt or bacteria treatment as CK.

[0070] Experimental results: According to the statistical results of the germination rate of corn after inoculating different bacterial pores at a salt concentration of 240 mM, 33 bacterial pores that can promote the germination of corn under salt stress were screened out.

[0071] III. Purification of strains

[0072] According to the preliminary screening results of the germination test under salt stress, find the bacterial pores that can promote the germination of corn under 240 mM salt stress and perform single-bacterium isolation and purification.

[0073] 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.

[0074] 2. Select individual 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.

[0075] 3. Then purify each single colony in step 2 by streaking on a TSB plate 3 times

[0076] 4. Pick the single colonies in step 3 into test tubes containing 3 mL of TSB liquid medium, and shake the bacteria at 30 °C and 170 rpm until the bacterial solution becomes turbid.

[0077] 5. Pipette 80 μL of the bacterial solution in step 4 into a 40% glycerol tube and store it in a -80 °C refrigerator.

[0078] Construct a single-bacterium resource library according to the preliminary screening results of crop germination tests under salt stress.

[0079] Experimental results: Five strains that can promote maize germination under salt stress were purified, namely TJ1-160, TJ1-229, TJ1-238, TJ1-185, and TJ1-179.

[0080] Example 3 Pot experiment verification of functional bacterial strains

[0081] Test strains: Five strains screened in Example 2

[0082] Test 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.

[0083] I. Preparation of bacterial suspension

[0084] 1. Inoculate the five functional bacterial strains obtained by screening and the control strain SQR9 into TSB liquid medium and culture at 30 °C and 170 rpm.

[0085] 2. After 24 h, centrifuge the bacterial solution, and then resuspend the bacterial cells with sterile water to make the OD of the bacterial suspension 600 value 1.0.

[0086] II. Germination and seedling raising of maize seeds

[0087] 1. First, the surface of maize seeds needs to be sterilized. This step is carried out in a laminar flow cabinet. Select plump and basically uniform-sized Zhengdan 958 maize seeds, disinfect the maize seeds with an alcohol solution with a volume fraction of 75% ethanol for 1 min, then soak the maize seeds in a sodium hypochlorite solution with a mass concentration of 2% for 10 min, and rinse with sterile ultrapure water 6 times to wash away the sodium hypochlorite solution attached to the seed surface.

[0088] 2. Place the soaked maize 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.

[0089] 3. Select the maize seedlings with consistent growth in step 2 and transplant them into the seedling-raising substrate for seedling raising. When the maize grows to the two-leaf and one-heart stage, select the maize seedlings with consistent growth and transplant them into the designated soil for subsequent experiments.

[0090] III. Pot Experiment Design

[0091] This experiment was conducted in the greenhouse of the Baima Scientific Research Base of Nanjing Agricultural University in Nanjing, Jiangsu Province from November 2023 to January 2024, and the experimental period was 28 days.

[0092] In this experiment, two salt gradients were set: 5‰ and 8‰. Each pot was filled with 500 g of soil. The experiment set a control group and a treatment group. The control group of potted plants was inoculated with no bacteria (blank control group) and inoculated with SQR9 (positive control group) respectively, and the treatment group was inoculated with 5 functional strains respectively.

[0093] 1. Select the corn seedlings with consistent growth in Step 2 and transplant them into the saline soil with two salt gradients (5‰ and 8‰). There are 5 corn seedlings in each pot, and 3 pots of controls are set for each treatment. Cultivate at room temperature and water appropriately to maintain the soil moisture content.

[0094] 2. One week after the corn transplantation, the bacterial suspensions of 5 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 kept at 10 7 CFU / g soil, that is, 10 7 CFU of bacteria were applied per gram of soil. Specifically, this step is as follows: one kind of bacterium is inoculated in one corn treatment group, the blank control group is not inoculated with bacteria, and sterile water equal to the volume of the bacterial suspension is added. The positive control group is inoculated with Bacillus amyloliquefaciens SQR9.

[0095] 3. Two weeks later, the bacterial suspension was added again in the same way, and the same volume of sterile water was watered in each pot of the control group. Under the light culture conditions of 30℃ and 16 / 8h, continue to grow for two weeks.

[0096] 4. After completing Step 3, various physiological and biochemical indexes of the corn plants were measured.

[0097] The content of malondialdehyde (MDA) was detected using a commercially available kit (purchased from Nanjing Jiancheng Bioengineering Institute).

[0098] The measurement results of various physiological and biochemical indexes of the corn plants are shown in Tables 1 - 2 and Figures 2 to 12 as follows.

[0099] Figure 2 Figure 5 shows the phenotypic observation results of the whole corn plants of the functional bacterium TJ1 - 185 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 TJ1 - 185; Figure 3 Figure 6 shows the phenotypic observation results of the corn potted plants of the functional bacterium TJ1 - 185 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 TJ1 - 185; Figure 4Phenotypic observation results of the whole maize plants of the functional bacterium TJ1-185 and the blank control group under 8‰ salt concentration. 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 TJ1-185. Figure 5 Phenotypic observation results of the maize potted plants of the functional bacterium TJ1-185 and the blank control group under 8‰ salt concentration. 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.

[0100] Figure 6 Graph showing the effects of five functional bacteria on the plant height of maize; among them, A shows the effects of the five functional bacteria on the plant height of maize under 5‰ salt concentration; B shows the effects of the five functional bacteria on the plant height of maize under 8‰ salt concentration.

[0101] Figure 7 Graph showing the effects of five functional bacteria on the root length of maize; among them, A shows the effects of the five functional bacteria on the root length of maize under 5‰ salt concentration; B shows the effects of the five functional bacteria on the root length of maize under 8‰ salt concentration.

[0102] Figure 8 Graph showing the effects of five functional bacteria on the fresh weight of the aboveground part of maize; among them, A shows the effects of the five functional bacteria on the fresh weight of the aboveground part of maize under 5‰ salt concentration; B shows the effects of the five functional bacteria on the fresh weight of the aboveground part of maize under 8‰ salt concentration.

[0103] Figure 9 Graph showing the effects of five functional bacteria on the fresh weight of maize roots; among them, A shows the effects of the five functional bacteria on the fresh weight of maize roots under 5‰ salt concentration; B shows the effects of the five functional bacteria on the fresh weight of maize roots under 8‰ salt concentration.

[0104] Figure 10 Graph showing the effects of five functional bacteria on the dry weight of the aboveground part of maize; among them, A shows the effects of the five functional bacteria on the dry weight of the aboveground part of maize under 5‰ salt concentration; B shows the effects of the five functional bacteria on the dry weight of the aboveground part of maize under 8‰ salt concentration.

[0105] Figure 11 Graph showing the effects of five functional bacteria on the dry weight of maize roots; among them, A shows the effects of the five functional bacteria on the dry weight of maize roots under 5‰ salt concentration; B shows the effects of the five functional bacteria on the dry weight of maize roots under 8‰ salt concentration.

[0106] Figure 12 Graph showing the effects of five functional bacteria on the malondialdehyde content of maize; among them, A shows the effects of the five functional bacteria on the malondialdehyde content of maize under 5‰ salt concentration; B shows the effects of the five functional bacteria on the malondialdehyde content of maize under 8‰ salt concentration.

[0107] Table 1 Detection results (mean values) of various physiological and biochemical indexes of corn plants in each treatment group under 15‰ salt concentration

[0108]

[0109]

[0110] Table 2 Detection results (mean values) of various physiological and biochemical indexes of corn plants in each treatment group under 5‰ salt concentration

[0111]

[0112] From Table 1 - 2 and Figures 2 to 12 it can be obtained that the experimental results are as follows

[0113] I. As Figure 2 shown, under the influence of salt stress, the growth and development of corn are severely inhibited. Under 5‰ salt concentration, the growth of corn basically stagnates, while inoculating with the functional bacterium TJ1-185 can help corn resume growth; under 8‰ salt concentration, the growth of corn is severely inhibited, with yellowing and curling of leaves, and inoculating with the functional bacterium TJ1-185 can help corn survive.

[0114] II. As Figure 6 shown, with the increase of salt concentration, the plant height of corn under high salt stress (8‰) is significantly lower than that under low salt stress (5‰). Under both salt concentrations, the plant height of corn seedlings treated with bacteria inoculation is significantly higher than that of the blank control treatment (CK) and the corn plant height under SQR9 treatment.

[0115] 1. Under 5‰ salt concentration, compared with the control group, the plant height of corn inoculated with the functional bacterium TJ1-185 increased by 65.5% compared with the blank control.

[0116] 2. Under 8‰ salt concentration, compared with the control group, the plant height of corn inoculated with the functional bacterium TJ1-185 increased by 75.0% compared with the blank control.

[0117] III. As Figure 7 shown, with the increase of salt concentration, the root length of corn under high salt stress (8‰) is significantly lower than that under low salt stress (5‰). Under both salt concentrations, the root length of corn seedlings treated with bacteria inoculation is significantly higher than that of the blank control treatment (CK) and the corn root length under SQR9 treatment.

[0118] 1. Under 5‰ salt concentration, compared with the control group, the root length of corn inoculated with the functional bacterium TJ1-185 increased by 124.2% compared with the blank control.

[0119] 2. At a salt concentration of 8‰, compared with the control group, the root length of maize inoculated with the functional bacterium TJ1-185 increased by 200.9% compared to the blank control.

[0120] IV. As Figure 8 shown, with the increase in salt concentration, the fresh weight of the above-ground part of maize under high salt stress (8‰) was significantly lower than that under low salt stress (5‰). At both salt concentrations, the fresh weight of the above-ground part of maize seedlings treated with inoculation was significantly higher than that of the blank control treatment (CK) and the maize above-ground part fresh weight under SQR9 treatment.

[0121] 1. At a salt concentration of 5‰, compared with the control group, the fresh weight of the above-ground part of maize inoculated with the functional bacterium TJ1-185 increased by 314.0% compared to the blank control.

[0122] 2. At a salt concentration of 8‰, compared with the control group, the fresh weight of the above-ground part of maize inoculated with the functional bacterium TJ1-185 increased by 266.7% compared to the blank control.

[0123] V. As Figure 9 shown, with the increase in salt concentration, the fresh weight of the roots of maize under high salt stress (8‰) was significantly lower than that under low salt stress (5‰). At both salt concentrations, the fresh weight of the roots of maize seedlings treated with inoculation was significantly higher than that of the blank control treatment (CK) and the maize root fresh weight under SQR9 treatment.

[0124] 1. At a salt concentration of 5‰, compared with the control group, the fresh weight of the roots of maize inoculated with the functional bacterium TJ1-185 increased by 110.1% compared to the blank control.

[0125] 2. At a salt concentration of 8‰, compared with the control group, the fresh weight of the roots of maize inoculated with the functional bacterium TJ1-185 increased by 50.5% compared to the blank control.

[0126] VI. As Figure 10 shown, with the increase in salt concentration, the dry weight of the above-ground part of maize under high salt stress (8‰) was significantly lower than that under low salt stress (5‰). At both salt concentrations, the dry weight of the above-ground part of maize seedlings treated with inoculation was significantly higher than that of the blank control treatment (CK) and the maize above-ground part dry weight under SQR9 treatment.

[0127] 1. At a salt concentration of 5‰, compared with the control group, the dry weight of the above-ground part of maize inoculated with the functional bacterium TJ1-185 increased by 168.5% compared to the blank control.

[0128] 2. At a salt concentration of 8‰, compared with the control group, the dry weight of the above-ground part of maize inoculated with the functional bacterium TJ1-185 increased by 84.7% compared to the blank control.

[0129] VII. AsFigure 11 As shown in the figure, with the increase of salt concentration, the dry weight of maize roots under high salt stress (8‰) was significantly lower than that under low salt stress (5‰). At both salt concentrations, the dry weight of maize seedling roots treated with inoculation was significantly higher than that of the blank control treatment (CK) and the maize roots treated with SQR9.

[0130] 1. At a salt concentration of 5‰, compared with the control group, the dry weight of maize roots inoculated with the functional bacterium TJ1-185 increased by 58.7% compared with the blank control.

[0131] 2. At a salt concentration of 8‰, compared with the control group, the dry weight of maize roots inoculated with the functional bacterium TJ1-185 increased by 84.7% compared with the blank control.

[0132] When plants are stimulated, a large amount of superoxide free radicals will be produced, 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.

[0133] VIII. As Figure 12 shown, under salt stress conditions, the malondialdehyde content in plant leaves increased significantly. At both salt concentrations, the malondialdehyde content in maize leaves treated with inoculation was significantly lower than that of the blank control treatment (CK) and the malondialdehyde content in maize treated with SQR9.

[0134] 1. At a salt concentration of 5‰, compared with the control group, the malondialdehyde (MDA) content in maize inoculated with the functional bacterium TJ1-185 decreased by 28.1% compared with the blank control.

[0135] 2. At a salt concentration of 8‰, compared with the control group, the malondialdehyde (MDA) content in maize inoculated with the functional bacterium TJ1-185 decreased by 32.6% compared with the blank control.

[0136] Example 4 16S Phylogenetic Identification of Strain TJ1-185

[0137] I. The 16S rDNA sequence of strain TJ1-185 was amplified and sequenced, and the sequencing results are shown in SEQ ID NO.1.

[0138] GATGGGGCGGCCTACACATGCAGTCGAGCGGATGAAGGGAGCTTGCTCCC

[0139] TGATTTAGCGGCGGACGGGTGAGTAATGCCTAGGAATCTGCCTGGTAGTGG

[0140] GGGATAACGTTCCGAAAGGAACGCTAATACCGCGTACGTCCTACGGGAGA

[0141] AAGCAGGGGACCTTCGGGCCTTGCGCTATCAGATGAGCCTAGGTCGGATTA

[0142] GCTAGTTGGTGAGGTAATGGCTCACCAAGGCGACGATCCGTAACTGGTCT

[0143] GAGAGGATGATCAGTCACACTGGAACTGAGACACGGTCCAGACTCCTACG

[0144] GGAGGCAGCAGTGGGGAATATTGGACAATGGGCGAAAGCCTGATCCAGCC

[0145] ATGCCGCGTGTGTGAAGAAGGTCTTCGGATTGTAAAGCACTTTAAGTTGGG

[0146] AGGAAGGGCTGCTGGTTAATACCCTGCAGTTTTGACGTTACCAACAGAATA

[0147] AGCACCGGCTAACTTCGTGCCAGCAGCCGCGGTAATACGAAGGGTGCAAG

[0148] CGTTAATCGGAATTACTGGGCGTAAAGCGCGCGTAGGTGGTTCGTTAAGTT

[0149] GGATGTGAAAGCCCCGGGCTCAACCTGGGAACTGCATCCAAAACTGGCGA

[0150] GCTAGAGTACGGTAGAGGGTGGTGGAATTTCCTGTGTAGCGGTGAAATGC

[0151] GTAGATATAGGAAGGAACACCAGTGGCGAAGGCGACCACCTGGACTGATA

[0152] CTGACACTGAGGTGCGAAAGCGTGGGGAGCAAACAGGATTAGATACCCTG

[0153] GTAGTCCACGCCGTAAACGATGTCAACTAGCCGTTGGAATCCTTGAGATTT

[0154] TAGTGGCGCAGCTAACGCATTAAGTTGACCGCCTGGGGAGTACGGCCGCA

[0155] AGGTTAAAACTCAAATGAATTGACGGGGGCCCGCACAAGCGGTGGAGCAT

[0156] GTGGTTTAATTCGAAGCAACGCGAAGAACCTTACCTGGCCTTGACATGCTG

[0157] AGAACTTTCCAGAGATGGATTGGTGCCTTCGGGAACTCAGACACAGGTGC

[0158] TGCATGGCTGTCGTCAGCTCGTGTCGTGAGATGTTGGGTTAAGTCCCGTAA

[0159] CGAGCGCAACCCTTGTCCTTAGTTACCAGCACCTCGGGTGGGCACTCTAA

[0160] GGAGACTGCCGGTGACAAACCGGAGGAAGGTGGGGATGACGTCAAGTCA

[0161] TCATGGCCCTTACGGCCAGGGCTACACACGTGCTACAATGGTCGGTACAAA

[0162] GGGTTGCCAAGCCGCGAGGTGGAGCTAATCCCATAAAACCGATCGTAGTC

[0163] CGGATCGCAGTCTGCAACTCGACTGCGTGAAGTCGGAATCGCTAGTAATCG

[0164] TGAATCAGAATGTCACGGTGAATACGTTCCCGGGCCTTGTACACACCGCCC

[0165] GTCACACCATGGGAGTGGGTTGCTCCAGAAGTAGCTAGTCTAACCTTCGGGGGGACGGTACCACGGAGATCCTGG。

[0166] II. The sequencing results were analyzed by BLAST alignment to construct a phylogenetic tree ( Figure 13 ), and the genus and species of the strain were preliminarily identified according to the name with higher homology to the strain to be tested. The strain TJ1-185 belongs to Pseudomonas bacteria, so it was renamed Pseudomonas TJ1-185.

[0167] III. Preservation of Pseudomonas TJ1-185

[0168] Pseudomonas (Pseudomonas sp) TJ1-185 provided by the present invention was deposited at the Guangdong Provincial Culture Collection of Microorganisms (abbreviation: CDMCC No. 64979; address: 5th Floor, Experimental Building, No. 100 Compound, Xianlie Middle Road, Yuexiu District, Guangzhou, Guangdong Province) on May 8, 2024, and the deposit number is CDMCC No. 64979.

[0169] Example 5

[0170] 1. Pseudomonas TJ1-185 and Pseudomonas putida PLW1 (deposit number: CCTCC NO: M 20241352) were inoculated into TSB liquid medium and cultured at 30 °C and 170 rpm.

[0171] 2. After 24 h, the bacterial solution was centrifuged, and then the bacterial cells were resuspended with sterile water to make the OD 600 value of 1.0, obtaining Pseudomonas TJ1-185 bacterial suspension and Pseudomonas putida PLW1 bacterial suspension respectively.

[0172] 3. The surface-sterilized corn seeds were placed in a 280 mM sodium chloride solution and soaked in the dark at 25 °C for 4 hours.

[0173] 4. The soaked seeds in step 3 were placed in a petri dish containing sterile water and 280 mM sodium chloride solution and lined with filter paper for cultivation. There were 3 seeds in each petri dish and six replicates.

[0174] 5. 100 μL of the Pseudomonas TJ1-185 bacterial suspension prepared in step 2 was added dropwise directly above the corn seeds in step 4 as the Pseudomonas TJ1-185 treatment group; 100 μL of the Pseudomonas putida PLW1 bacterial suspension prepared in step 2 was added dropwise directly above the corn seeds in step 4 as the Pseudomonas putida PLW1 treatment group. At the same time, a treatment group without adding the microbial agent was set as the negative control (adding sterile water equal to the amount of the bacterial solution in the Pseudomonas putida PLW1 treatment group). They were placed in a 25 °C light incubator to germinate, and cultured for 4 d with a day-night ratio of 16 h / 8 h.

[0175] 6. Observe the germination of different treatment groups in step 5 as shown in Table 3.

[0176] Germination status (mean) of different treatment groups in Table 3

[0177] Group Germination rate Negative control group 0 Pseudomonas sp. TJ1-185 treatment group 78.6％ Pseudomonas putida PLW1 treatment group 37.3％

[0178] As can be seen from Table 3, at a salt concentration of 280 mM, the germination rate of corn treated with the bacterial suspension of strain TJ1-185 was 78.6%, while that of corn treated with the bacterial suspension of Pseudomonas putida PLW1 was 37.3%. This shows that, compared with Pseudomonas putida PLW1, strain TJ1-185 can more significantly improve the germination rate of corn and enhance the salt tolerance of corn.

[0179] 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 Pseudomonas sp. TJ1-185, characterized in that: The deposit number is CDMCC No.64979.

2. A bacterial agent, characterized in that It includes the Pseudomonas bacterium TJ1-185 described in claim 1.

3. The bacterial agent according to claim 2, characterized in that: The OD of Pseudomonas bacteria TJ1-185 in the bacterial agent 600 The value of is ≥1.

0.

4. The method for preparing the bacterial agent according to claim 2 or 3, characterized in that: include: The Pseudomonas bacteria TJ1-185 is cultured in a culture medium to obtain a bacterial agent.

5. The preparation method according to claim 4, characterized in that: The culture temperature is 30-37° C.; the culture time is 18-30 hours; and the culture rotation speed is 150-250 rpm.

6. Use of the Pseudomonas bacterium TJ1-185 described in claim 1, the bacterial agent described in claim 2 or 3, or the bacterial agent prepared by the preparation method described in claim 4 or 5 in promoting plant growth and / or improving plant salt tolerance.

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

8. The use according to claim 6, characterized in that: The promoting plant growth includes any one or more of increasing plant height, increasing plant root length, increasing plant aboveground fresh weight, increasing plant root fresh weight, increasing plant aboveground dry weight and increasing plant 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 plant salt stress tolerance, characterized in that: include: The bacterial agent comprising the Pseudomonas bacteria TJ1-185 according to claim 1 is applied during the growth of the plants.

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