A strain of Microbacterium salsa 7-6 and its application

Abstract

The invention discloses a strain of Microbacterium suaedae 7-6 and its application, belonging to the field of microorganisms. The Microbacterium suaedae 7-6 provided by the invention has a preservation number of CGMCC No.31312. The strain can tolerate 120g L ‑1 The strain can produce IAA, iron carriers and form biofilms, and has the potential to promote plant growth. The strain can promote the germination of rice and tomato seeds under salt stress. The strain was inoculated into the rhizosphere of potted tomatoes and improved the growth index of tomatoes under 450mM salt stress. The strain can be used to make functional microbial fertilizers to enhance crop tolerance to salt stress and increase crop yields in saline-alkali land, which is of great significance for the improvement of saline-alkali land.

Description

Technical Field

[0001] The invention belongs to the field of microorganisms, and specifically relates to a strain of Microbacterium salsa 7-6 and an application thereof. Background Art

[0002] Saline-alkali land is a special type of soil widely distributed around the world. It is characterized by high salinity and alkalinity, which seriously restricts the sustainable development of agricultural production and ecosystems. In saline-alkali land, the high salt concentration in the soil will cause water imbalance in plants, affect the normal growth and development of plants, and ultimately lead to reduced crop yields or even crop failure. With the impact of global climate change and human activities, the area of ​​saline-alkali land is constantly expanding. There is an urgent need to find effective strategies to improve the salt tolerance of plants under saline-alkali conditions to ensure food security and ecological environment stability.

[0003] In recent years, microbial agents have received extensive attention because of their ability to improve soil environment, promote plant growth, and enhance plant stress resistance. In saline-alkali land, some specific microbial strains can significantly improve the salt tolerance of plants through various mechanisms, such as producing growth hormones, regulating ion balance in plants, activating antioxidant systems in plants, fixing nitrogen, and dissolving phosphorus. These microbial agents can not only directly promote plant growth and development, but also play a long-term regulatory role in the soil, improve the physical and chemical properties of the soil, and reduce the impact of salt-alkali stress on plants.

[0004] However, although microbial agents have shown great potential in promoting salt-tolerant growth of plants, existing types of agents and application technologies still have limitations, such as inaccurate strain screening, poor stability of agents under different saline-alkali conditions, and unclear interaction mechanisms with plants. Therefore, the development of microbial agents for saline-alkali land that can effectively promote the salt-tolerant growth of plants has important scientific significance and application prospects for increasing the yield of saline-alkali land crops and promoting the sustainable utilization of saline-alkali land. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a bacterial strain capable of enhancing the salt stress tolerance of crops, thereby increasing the biomass of crops on saline-alkali land and realizing the effective utilization of saline-alkali land.

[0006] The technical solution of the present invention is: a strain of Microbacterium suaedae 7-6, which was deposited in the General Microbiology Center of China Microbiological Culture Collection Administration on July 16, 2024, at the Institute of Microbiology, Chinese Academy of Sciences, No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing; the deposit number is CGMCC No.31312.

[0007] A bacterial agent containing the above-mentioned Microbacterium suaedae 7-6.

[0008] The use of the above-mentioned Microbacterium suaedae 7-6 or bacterial agent in improving the salt tolerance of plants.

[0009] The application of the above-mentioned Microbacterium suaedae 7-6 or bacterial agent in increasing the biomass of plants in saline-alkali land.

[0010] Furthermore, the plant is rice or tomato.

[0011] The invention provides a strain capable of improving the salt stress tolerance of tomatoes. The strain can significantly improve the germination rate and root length of rice and tomato seeds under salt stress, significantly reduce the malondialdehyde (MDA) content in the root system of tomato seeds, and significantly improve the activities of catalase (CAT), peroxidase (POD) and superoxide dismutase (SOD) in the root system of tomato seeds. The strain was inoculated into the rhizosphere of potted tomatoes. Under salt stress, it can significantly improve the growth indicators of tomatoes (plant height, aboveground fresh weight, root weight, total fresh weight, root length, etc.); significantly improve the photosynthetic efficiency of tomato leaves; significantly increase the relative water content (DW), proline and soluble sugar content in tomato leaves; significantly reduce the malondialdehyde (MDA) content in tomato leaves, increase the catalase (CAT) activity and peroxidase (POD) activity in tomato leaves, and reduce the superoxide dismutase (SOD) activity; significantly reduce the malondialdehyde (MDA) content in tomato roots, and increase the catalase (CAT) activity and superoxide dismutase (SOD) activity in tomato roots. In addition, Suaeda salsa 7-6 also has the ability to tolerate 120g L -1 It has the potential plant growth-promoting abilities of creating a strong alkaline environment of NaCl and pH=11, producing IAA and siderophores, and is a rhizospheric growth-promoting microbacterium.

[0012] Compared with the prior art, the present invention has the following beneficial effects:

[0013] 1. The effective strain in the present invention originates from saline-alkali soil, has strong adaptability to saline-alkali environment, and has the characteristics of producing IAA and siderophore. The hemolytic reaction of the strain is negative and harmless to humans.

[0014] 2. The Microbacterium 7-6 provided by the present invention exhibits a significant growth-promoting effect on tomatoes under extremely high salt stress (450 mM NaCl) conditions, and the microbial agent developed using this strain shows broad application potential in improving saline-alkali land and ensuring crop growth.

[0015] Collection information:

[0016] Microbacterium suaedae 7-6 was deposited on July 16, 2024 at the General Microbiology Center of China Culture Collection Administration, address: No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing, Institute of Microbiology, Chinese Academy of Sciences; the deposit number is CGMCC No.31312. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The following are photos of the strain colony phenotype and cell phenotype.

[0018] Figure 2 This is the growth curve of the strain.

[0019] Figure 3 To test the salt and alkali tolerance of the strain.

[0020] Figure 4 To test the biofilm forming ability of strains.

[0021] Figure 5 To test the hemolytic ability of strains.

[0022] Figure 6 It is the rice seed growth index under different treatments in the strain-promoted salt-tolerance germination test in Example 4.

[0023] Figure 7 It is the tomato seed growth index under different treatments in the strain-promoted salt-tolerance germination test in Example 4.

[0024] Figure 8 These are the malondialdehyde content and antioxidant enzyme activity indicators of tomato seeds under different treatments in the strain salt-tolerance germination test in Example 4.

[0025] Fig. 9 These are the phenotypic photos and growth indicators of tomatoes under different treatments in the salt tolerance pot experiment in Example 5.

[0026] Fig.10 It is the photosynthesis efficiency of tomatoes under different treatments in the salt tolerance pot experiment in Example 5.

[0027] Fig.11 The water content and osmotic regulating substance content of tomato cells under different treatments in the salt tolerance pot experiment in Example 5.

[0028] Fig.12 These are the malondialdehyde content and antioxidant enzyme activity indicators of tomatoes under different treatments in the salt tolerance pot experiment in Example 5. DETAILED DESCRIPTION

[0029] The experimental methods in the following examples are conventional methods unless otherwise specified. The experimental materials used in the following examples are purchased from commercial channels unless otherwise specified.

[0030] Rice variety Nanjing 46: Available from various fruiting stores and online stores.

[0031] Tomato variety Cooperation 903: Available from various fruit stores and online stores.

[0032] Example 1. Strain origin, morphology, growth ability test and preservation

[0033] 1. Sample collection and strain isolation

[0034] Rhizosphere soil of Qinghai desert halophytes was collected, the soil suspension was gradient diluted, and a suitable gradient was selected to be spread on TSB medium, cultured at 30°C overnight, and the strains on the plate were separated and purified to screen strain 7-6.

[0035] 2. Molecular identification of Microbacterium 7-6

[0036] The 16S rDNA sequence of strain 7-6 was amplified and sequenced, and the sequencing result is shown in SEQ ID No. 1. After identification, it can be determined that strain 7-6 belongs to Microbacterium suaedae. Microbacterium suaedae 7-6 is referred to as Microbacterium 7-6. Microbacterium 7-6 has only 2 genomes in the Genome database of NCBI (National Center for Biotechnology Information), and is a rare species that has been rarely studied.

[0037] 3. Morphological observation of Microbacterium 7-6

[0038] 1. Colony phenotype observation

[0039] Use an inoculation loop to dip the strain storage solution of Microbacterium 7-6 in the glycerol tube, streak it on a TSB solid plate, place it in a 30℃ biochemical incubator for constant temperature culture and activation until a single colony grows, take a photo and record the colony phenotype. Figure 1 As shown in middle A, the colonies of Microbacterium 7-6 are round and raised, milky white, smooth, shiny, slightly transparent, sticky, and have complete edges.

[0040] 2. Cell phenotype observation

[0041] 2.1. Strain preparation: After activating Microbacterium 7-6, take 1% of the inoculum into TSB liquid culture medium and culture at 30°C and 200 rpm for 1 day.

[0042] 2.2. Sample preparation:

[0043] (1) Pre-fixation: fix in 2.5% glutaraldehyde solution at 4°C overnight;

[0044] (2) Rinsing: Pour off the fixative solution and rinse the sample three times with 0.1 M phosphate buffer (pH 7.0), 15 min each time;

[0045] (3) Refixation: Fix the sample with 1% osmium acid solution for 1-2 hours;

[0046] (4) Rinse: Pour off the fixative solution and rinse the sample three times with 0.1 M phosphate buffer (pH 7.0), 15 min each time;

[0047] (5) Dehydration: Dehydrate the samples with ethanol solutions of gradient concentrations (including 50%, 70%, 80%, 90% and 95%), with each concentration treated for 15 min; then treat with 100% ethanol twice, each time for 20 min;

[0048] (6) Overtreatment: Treat the sample with a mixture of ethanol and isoamyl acetate (V / V = 1 / 1) for 30 min, and then treat the sample with pure isoamyl acetate for 1-2 h;

[0049] (7) Critical point drying;

[0050] (8) Coating and observation.

[0051] 2.3. Electron microscopy: Use Hitachi 8100 electron microscope to observe and take photos of the strain morphology.

[0052] The electron microscopic results of Microbacterium 7-6 are as follows Figure 1 As shown in B, the cells are approximately 1.0 μm in diameter, short rod-shaped, with a smooth surface and uniform cell morphology.

[0053] 4. Growth ability test of strains

[0054] 1. Use an inoculation loop to dip the Microbacterium 7-6 preservation solution in the glycerol tube, streak it on a TSB solid plate, and place it in a 30℃ biochemical incubator for constant temperature culture and activation until a single colony grows.

[0055] 2. Use a sterile pipette tip to pick up a single colony, inoculate it into a test tube containing 3 mL of TSB liquid culture medium, and culture it in a 30°C constant temperature shaker for 24 hours to prepare the seed solution.

[0056] 3. Inoculate the seed solution into fresh TSB liquid medium at a 1% inoculum volume, and dispense 200 μL per well into a sterile 100-well plate dedicated to the bacterial automatic growth curve analyzer. Place the well plate in the instrument, shake and culture at 30°C, and measure the OD every 30 minutes. 600 The value was obtained and cultured for 25 hours. Five replicates were set up and blank TSB medium without strain seed solution was used as control. After the experiment, the data were exported and analyzed and graphed using Excel software.

[0057] Specific results such as Figure 2 As shown, the growth curve of strain 7-6 is S-shaped, with 0-2h as the lag phase, 5-20h as the logarithmic growth phase, and reaching the plateau phase after 20h. The strain has a short lag phase, grows rapidly, can reach a high population density in the plateau phase, is easy to culture, and is convenient for liquid fermentation of microbial agents.

[0058] V. Storage of strain 7-6

[0059] The Microbacterium suaedae 7-6 provided by the present invention has been deposited in the General Microbiology Center of the China Microorganism Culture Collection Committee (referred to as CGMCC; address: No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing, Institute of Microbiology, Chinese Academy of Sciences; Postal Code: 100101) on July 16, 2024, and the deposit number is CGMCC No.31312.

[0060] Example 2: Test of plant growth-promoting related indicators of Microbacterium 7-6

[0061] 1. Test of salt and alkali resistance

[0062] a. Salt tolerance test

[0063] The seed solution of Microbacterium 7-6 was prepared by the method in Example 1, and inoculated with 1% inoculum into the NaCl contents of 5, 20, 40, 60, 80, 100, and 120 g L -1 The culture medium was added to fresh TSB medium and dispensed into 96-well plates at 200 μL per well. The plates were placed in a shaking culture at 30°C and 170 rpm. After 48 h, the OD value of the bacterial solution was measured using an ELISA reader. 600 Data analysis and chart drawing were performed using Excel software.

[0064] b. Alkali resistance test

[0065] The seed solution of Microbacterium 7-6 was prepared by the method in Example 1, and inoculated into fresh TSB medium with pH values ​​of 6, 7, 8, 9, 10, and 11 at a 1% inoculum, and dispensed into 96-well plates at 200 μL per well. The well plates were placed at 30°C and 170 rpm for shaking culture. After 48 h, the OD value of the bacterial solution was measured using an ELISA reader. 600 Data analysis and chart drawing were performed using Excel software.

[0066] Specific test results such as Figure 3 The results showed that Microbacterium 7-6 had the ability to tolerate 120 g L -1 The ability to tolerate NaCl and a strong alkaline environment of pH = 11 can ensure the normal survival of Microbacterium 7-6 in saline-alkali environments and the stable performance of its plant growth-promoting function.

[0067] 2. IAA production capacity determination

[0068] Microbacterium 7-6 was inoculated in a medium containing 1 g L -1 The culture medium was incubated in Landy medium containing L-tryptophan at 25°C and 140 rpm for 72 h. 1 mL of the culture medium was centrifuged at 12,000 × g for 5 min and the supernatant was collected for determination using an Elisa kit. Calculation of IAA production (mg L) of Microbacterium 7-6 -1 ).

[0069] IAA is a type of plant auxin that regulates plant growth and development. The IAA produced by the strain can directly promote plant growth and development and is one of the important plant growth-promoting indicators of the strain. The results showed that Microbacterium 7-6 has a certain ability to produce IAA, and the yield can reach 14.40±0.22nmol L -1 , indicating that it has certain plant growth promoting potential.

[0070] 3. Determination of iron carrier production capacity

[0071] The seed solution of Microbacterium 7-6 was prepared by the method in Example 1, and inoculated into TSB liquid medium at a 1% inoculum, cultured at 30°C, 170 rpm for 24 h, centrifuged at 12000 rpm for 15 min, and the supernatant was sterilized by membrane, mixed with an equal volume of CAS detection solution, reacted fully, and the OD was measured. 630 , and the absorbance value As was obtained, and double distilled water was used as a control to adjust the value to zero; uninoculated culture medium and CAS detection solution were mixed in equal volumes, and OD was measured. 630, and the absorbance value Ar was obtained. The As / Ar value represents the relative content of siderophore in the sample. The siderophore content determination was repeated 3 times. As / Ar ranged from 1.0 to 0 with an interval of 0.2. Every time As / Ar decreased by 0.2, a "+" was added. There were five levels from "+" to "+++++". The higher the level, the stronger the siderophore production ability of the strain.

[0072] CAS blue test solution formula:

[0073] Solution A: Dissolve 60.5 mg CAS in 50 mL deionized water, add 10 mL FeCl3 solution (containing 1 mM FeCl3·6H2O, 10 mM HCl); Solution B: Dissolve 72.9 mg HDTMA (hexadecyltrimethylammonium bromide) in 40 mL deionized water; slowly inject solution A into solution B along the wall of the beaker to obtain CAS blue detection solution.

[0074] Most beneficial bacteria can secrete low-molecular-weight, strong-chelating iron carriers when iron is scarce, which improves the absorption and transportation of iron ions by microorganisms, increases the mobility of iron ions in the environment, and promotes the growth of plants in iron-deficient environments. In addition, the iron carrier affinity of bacteria is generally higher than that of fungal iron carriers, and bacteria can use the iron carriers they produce to deprive pathogenic fungi of the iron ions chelated by the iron carriers. Therefore, the ability to produce iron carriers is an important evaluation indicator of the growth-promoting / disease-resistant ability of probiotic microorganisms. The iron carrier production capacity of Microbacterium 7-6 is at the first level "+", indicating that it has the ability to produce iron carriers, but the ability is weak, suggesting that its plant growth-promoting effect may not be dominated by iron carrier production.

[0075] 4. Biofilm formation ability test

[0076] The seed solution of Microbacterium 7-6 was prepared by the method in Example 1, and inoculated into a 48-well plate containing 1 mL of fresh TSB medium at a 1% inoculum. The plate was sealed with plastic wrap and cultured statically in a 30° C. biochemical incubator. The biofilm formation was observed at different time points and photographed and recorded.

[0077] The biofilm-forming ability of a strain is directly proportional to its ability to colonize on the plant root surface. Figure 4 As shown in the figure, Microbacterium 7-6 has the ability to form biofilm, but the biofilm-forming ability is weak. Therefore, it is speculated that the plant growth-promoting ability of the strain does not rely on root surface colonization, but may rely on root colonization or the production of signal substances in the rhizosphere.

[0078] Example 3, hemolytic reaction of Microbacterium 7-6

[0079] Microbacterium 7-6 was inoculated on a sheep blood plate (Haibo Biotech) and incubated at 30°C for 48 hours. No hemolysis zone was observed ( Figure 5), that is, the hemolytic reaction is negative, and it can be used for the development and utilization of microbial fertilizers.

[0080] Example 4: Experiment on promoting salt-tolerant germination of seeds by Microbacterium 7-6

[0081] a. Preparation of bacterial suspension

[0082] After the strain was activated, it was inoculated into TSB liquid medium at an inoculum volume of 1% and cultured at 30°C and 200 rpm with shaking. The supernatant was removed by centrifugation to collect the bacteria, and the bacteria were washed 3 times with a 250 mM sterile NaCl solution to a final concentration of OD = 1. The bacterial suspension with OD = 1 was diluted with a 250 mM sterile NaCl solution to obtain the test bacterial suspensions: the original concentration bacterial suspension (7-6_1), the bacterial suspension diluted 10 times (7-6_2), and the bacterial suspension diluted 100 times (7-6_3).

[0083] b. Seed treatment

[0084] Select an appropriate amount of rice / tomato seeds with full grains and comparable grain size, clean the surface dust with distilled water, soak them in 1% NaClO solution for 2 minutes, soak them in 75% alcohol for 5 minutes, rinse them with sterile deionized water for 5-7 times, and soak the sterilized rice / tomato seeds in sterile deionized water at room temperature for 24 hours for later use.

[0085] c. Germination test

[0086] Take 20 rice / tomato seeds and place them evenly in a 9 cm culture dish covered with two layers of filter paper. Five treatments were set up in the experiment: ddH2O treatment (10 mL sterile ddH2O), NaCl treatment (10 mL sterile 250 mM NaCl solution), 7-6_1 treatment (10 mL 7-6_1 bacterial suspension), 7-6_2 treatment (10 mL 7-6_2 bacterial suspension), 7-6_3 treatment (10 mL 7-6_3 bacterial suspension). Each treatment was repeated 3 times, and the culture dish was placed in a light incubator (25°C, 80% RH) for cultivation. When the germination rate of the seeds in the ddH2O group reached more than 90%, the experiment was terminated, and a series of data such as germination rate, seed root length (seeds germinate first and then germinate, so the seed root length is counted), and root enzyme activity were recorded and measured.

[0087] High-salt environment will form hyperosmotic stress and inhibit the germination of plant seeds. Microbacterium 7-6 can significantly alleviate the inhibition of high-salt environment on the germination of rice and tomato seeds, and improve the germination rate and root length of seeds in high-salt environment. The lower the concentration of bacterial suspension, the better the effect ( Figure 6 , Figure 7 ).

[0088] Salt stress can also lead to oxidative stress in plants, causing a series of oxidative substances to be produced in the plant body, resulting in oxidative damage to tissues. Malondialdehyde (MDA) is a toxic substance produced in plants due to oxidative stress. It is a sign of plant tissue damage. The higher its content, the more serious the damage to plant tissues. Microbacterium 7-6 can reduce the content of malondialdehyde (MDA) in the roots of tomato seeds during the germination stage, reducing the degree of damage to plant tissues under salt stress ( Figure 8 ). Catalase (CAT), peroxidase (POD) and superoxide dismutase (SOD) are antioxidant enzyme systems in plants that are responsible for removing reactive oxygen species (ROS). Microbacterium 7-6 can significantly increase the activities of catalase (CAT), peroxidase (POD) and superoxide dismutase (SOD) in the roots of tomato seeds during the germination stage, alleviating the oxidative damage caused by salt stress inside tomato seeds.

[0089] Example 5: Potted plant experiment on bacterial strains promoting salt tolerance growth

[0090] 1. After surface disinfection, the Hezuo 903 tomato seeds were sown in moist vermiculite and placed in a light incubator for seedling cultivation (25°C, 70% RH, 2500LUX). Seedlings with uniform growth were selected at the cotyledon stage and transplanted into pots (1 L in volume, with a tray containing 800 mL of substrate) filled with seedling cultivation peat.

[0091] 2. 5 days after transplanting the tomato seedlings, treat the potted plants as follows:

[0092] H2O group: Only tap water was added during the planting period, and 100 mL of tap water was added every 3 days, for a total of 10 times.

[0093] NaCl group: A total of 21.21 g NaCl was added (making the final salt concentration in the substrate about 450 mM), and each addition was made by pouring the salt solution into the root system. The experiment adopted the interval multi-frequency salt addition method: 100 mL of 360 mM NaCl solution was added every 3 days, for a total of 10 times.

[0094] NaCl+7-6 group: In addition to adding NaCl to the NaCl treatment group, Microbacterium 7-6 was inoculated when the NaCl solution was first added, so that the final concentration of Microbacterium 7-6 was 1×10 7 CFU g -1 earth.

[0095] 3. The potted plants were cultured in a light incubator for 5 weeks, and the growth indexes of tomato plants (plant height, root length, fresh weight of aboveground part and fresh weight of underground part), plant photosynthesis indexes (photosynthetic efficiency), plant cell osmosis-related indexes (proline content, soluble sugar content, relative water content of leaves), plant oxidative damage and antioxidant enzyme system (MDA content, CAT activity, POD activity and SOD activity of aboveground part, MDA content, CAT activity, POD activity and SOD activity of underground part) were observed, recorded and measured. The photosynthetic efficiency of tomato leaves was measured by advanced photosynthetic fluorescence meter LI-6800; the relative water content of leaves was calculated by the following formula: {(fresh weight of leaves - dry weight of leaves) / (water-saturated weight of leaves - dry weight of leaves)}×100%; the proline content, soluble sugar content, MDA content, CAT activity, POD activity and SOD activity of aboveground and underground parts were measured by commercial kits (all purchased from Solebow Biotechnology Co., Ltd.), and the measurement method is detailed in the kit instructions.

[0096] The results showed that Microbacterium 7-6 could improve the growth indexes of tomatoes (plant height, root length, fresh weight of aboveground parts, fresh weight of underground parts, etc.) under salt stress, ensuring the normal growth of tomatoes. Its biomass was even higher than that of tomatoes in the control group without salt addition ( Fig. 9 ). It shows that Microbacterium 7-6 has a superior growth-promoting effect on tomatoes under extremely severe salt stress (450mM NaCl), and the microbial agent developed using it has broad prospects in saline-alkali land improvement and crop growth guarantee.

[0097] Microbacterium 7-6 can significantly improve the photosynthetic efficiency of tomato leaves under salt stress ( Fig.10 ), the improvement of photosynthesis is a prerequisite for the good growth and development of plants.

[0098] In a high-salt environment, the water potential of plant cells will be higher than the water potential of the soil solution, causing the water molecules in the plant body to lose to the outside of the cell, resulting in physiological drought and water shortage in the plant. In response to this stress, plants will synthesize organic substances to regulate their own cellular osmotic pressure, such as proline and soluble sugars. Microbacterium 7-6 can significantly increase the relative water content (DW), proline content and soluble sugar content in tomato leaves under salt stress. Proline and soluble sugars can increase the osmotic pressure in plant tissues, ensure the stability of the internal water content of plants under hyperosmotic stress, and even make their growth ability better (compared with the water treatment group) ( Fig.11 ).

[0099] Microbacterium 7-6 can reduce the content of malondialdehyde (MDA) in tomato leaves and roots, and reduce the degree of damage to plant tissues under salt stress. In addition, Microbacterium 7-6 also significantly increased the activity of catalase (CAT) and peroxidase (POD) in tomato leaves under salt stress, reduced the activity of superoxide dismutase (SOD), and significantly increased the activity of catalase (CAT) and superoxide dismutase (SOD) in tomato roots under salt stress. This shows that Microbacterium 7-6 can relieve the stress effect of tomato plants under salt adversity by regulating the above three antioxidant enzyme systems ( Fig.12 ).

Claims

1. A strain of Suaeda salsa Microbacterium suaedae )7-6, deposited in the General Microbiology Center of China Microorganism Culture Collection Administration, with the deposit number CGMCC No.31312.

2. Containing the Microbacterium salsarum described in claim 1 ( Microbacterium suaedae )7-6 of the bacterial agent.

3. The Microbacterium salsarum according to claim 1 ( Microbacterium suaedae ) 7-6 or the use of the bacterial agent described in claim 2 for improving the salt tolerance of plants, wherein the plant is rice or tomato.

4. The Microbacterium salsarum according to claim 1 ( Microbacterium suaedae ) 7-6 or the use of the bacterial agent described in claim 2 to increase the biomass of plants in saline-alkali land.

5. The use according to claim 4, characterized in that: The plant is rice or tomato.

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