Halotolerant plant growth-promoting rhizobacteria and application thereof

Abstract

The application provides a salt-tolerant plant rhizosphere growth-promoting bacterium and application thereof, and belongs to the technical field of plant growth-promoting bacteria. Rossellomorea marisflavi The salt-tolerant plant rhizosphere growth-promoting bacterium is classified as Rm-FG10-5, has been named as Rm-FG10-5, and has been preserved in the China General Microbiological Culture Collection Center (CGMCC) on July 3, 2024, and the address is No. 3, Beichen West Road, Chaoyang District, Beijing, and the preservation number is CGMCC No. 31158. The Rm-FG10-5 is a salt-tolerant plant rhizosphere growth-promoting bacterium isolated and screened from pepper rhizosphere soil, and can be cultured by using nutrient broth medium. The Rm-FG10-5 strain can significantly improve the antioxidant enzyme activity of plant roots, the expression amount of an antioxidant-related gene of plant roots or the expression amount of an ion balance-related gene of plant roots, so that it can stably colonize in plant roots and rhizosphere soil, relieve salt stress, improve root activity, improve the stress resistance of plants, promote plant growth, and thus achieve the purpose of improving yield and quality.

Description

Technical Field

[0001] This invention belongs to the field of microbiology, specifically relating to a salt-tolerant plant rhizosphere growth-promoting bacterium and its application. Background Technology

[0002] Plant growth-promoting rhizobacteria (PGPR) are beneficial bacteria that exist in the rhizosphere environment of plants and promote plant growth through direct effects such as producing plant hormones and dissolving inorganic phosphorus, as well as indirect effects such as competing for ecological niches and inducing systemic resistance. Recent studies have shown that PGPR strains can effectively colonize plant roots and rhizosphere soil, exhibiting significant growth-promoting, disease-preventing, and yield-increasing effects. They also regulate the microecological environment of the rhizosphere soil and alleviate ecological pollution, making them an effective approach for the sustainable development of organic ecological agriculture with broad application prospects.

[0003] Soil salinization is a major stressor limiting the yield and quality of greenhouse vegetables. Soil salinization refers to the excessive accumulation of salt in the soil, leading to increased soil pH and ion imbalance. Salt stress affects plant growth and development, reduces photosynthetic efficiency, and causes symptoms such as yellowing and wilting of leaves. During fruit development, salt stress can also cause fruit deformation and cracking, severely impacting yield and market value. Plant rhizosphere growth-promoting bacteria play a crucial role in regulating the rhizosphere environment, controlling growth and development, and enhancing systemic resistance. In recent years, the regulation of soil microbial communities and microecology by plant rhizosphere growth-promoting bacteria to maintain soil health and improve plant stress tolerance has received widespread attention. Identifying and utilizing plant growth-promoting bacteria that interact with vegetable crops to alleviate stress provides a new strategy for improving the stress resistance of greenhouse vegetables and opens new avenues for discovering new mechanisms related to stress tolerance.

[0004] Chinese invention patent application CN 111979149 A discloses a halophilic Bacillus SY1836 and its applications. The halophilic Bacillus SY1836, with accession number CGMCC No. 20080, exhibits good antagonistic effects against various plant pathogens. When applied to chili pepper growth, it can effectively reduce the disease index of chili peppers, demonstrating significant control over chili pepper blight. Simultaneously, this halophilic Bacillus SY1836 can also significantly increase the plant height and fresh weight of chili peppers during their growth.

[0005] However, there are few reports on salt-tolerant plant rhizosphere growth-promoting bacteria belonging to Rossellomorea marisflavi in ​​the existing technology. Summary of the Invention

[0006] In view of this, the first objective of the present invention is to provide a salt-tolerant plant rhizosphere growth-promoting bacterium belonging to *Rossellomorea marisflavi*. Specifically, a salt-tolerant plant rhizosphere growth-promoting bacterium, *Rossellomorea marisflavi* Rm-FG10-5, was deposited on July 3, 2024, at the China General Microbiological Culture Collection Center (CGMCC), located at No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing, with accession number CGMCC No. 31158.

[0007] Rm-FG10-5 bacteria was isolated in August 2021 from the rhizosphere soil of chili peppers that had been continuously cropped for 5 years in Fugou County, Henan Province. It was screened through the TSA streak plate method containing NaCl, the double-layer filter paper method, and the pot salt tolerance effect test. It is a plant rhizosphere bacterium with salt tolerance and salt stress relief function and can be cultured in nutrient broth medium.

[0008] The Rm-FG10-5 strain has rod-shaped cells, 0.5–0.8 μm in diameter and 2.5–3.2 μm in length. It produces spores, is Gram-positive, and grows into yellow, opaque, smooth, nearly circular colonies with relatively regular edges on nutrient gravy (NA) medium. Turbidity appears after 24 hours of culture in NB medium. The growth temperature range is 5–45℃, with an optimum growth temperature of 30℃. The maximum salt tolerance is 16%. It can utilize sucrose, glucose, galactose, maltose, tannic acid, and mannitol, but cannot utilize citric acid. It is positive for nitrite reduction, but negative for nitrate reduction, gelatin liquefaction, and H2S reaction. The 16S rRNA sequence of this strain, as shown in SEQ No. 1, is 1457 bp in length and shows 99.72% homology with the 16S rRNA sequence of *Rosellomorea marisflavi*. In summary, based on the colony morphology, culture conditions, and molecular biological identification results, this strain is classified and named Rossellomorea marisflavi, with the name Rm-FG10-5.

[0009] A second objective of this invention is to provide a bacterial suspension containing rhizosphere growth-promoting bacteria for salt-tolerant plants, comprising the aforementioned Rm-FG10-5 strain. Preferably, the concentration of Rm-FG10-5 in the bacterial suspension is (1-5) × 10⁻⁶. 8 CFU / mL. This bacterial culture was mainly prepared by inoculating the above-mentioned Rm-FG10-5 strain into nutrient broth medium and fermenting it at 28-32℃ for 16-72 hours.

[0010] Furthermore, the bacterial solution also includes magnesium sulfate. Preferably, the concentration of magnesium sulfate in the bacterial solution is 0.05–0.1 mol / L.

[0011] A third objective of this invention is to provide an application of the above-mentioned salt-tolerant plant rhizosphere growth-promoting bacteria or its bacterial solution in promoting the colonization of the Rm-FG10-5 strain in vegetable roots or vegetable rhizosphere soil.

[0012] The fourth objective of this invention is to provide an application of the above-mentioned salt-tolerant plant rhizosphere growth-promoting bacteria or their bacterial solutions in promoting the salt tolerance of vegetables or alleviating salt stress.

[0013] The fifth objective of this invention is to provide a method for promoting the growth of the above-mentioned salt-tolerant plant rhizosphere bacteria or their bacterial solutions in promoting the activity of antioxidant enzymes, the expression levels of antioxidant-related genes, or the expression levels of ion balance-related genes in the roots of vegetables.

[0014] The vegetables mentioned include fruit vegetables such as chili peppers, tomatoes, and cucumbers.

[0015] The sixth objective of this invention is to provide a method for promoting the growth of vegetable plants as described above, comprising:

[0016] Applying the above-mentioned salt-tolerant plant rhizosphere growth-promoting bacteria or their bacterial solution to the plants of the vegetables, wherein the total viable count of the salt-tolerant plant rhizosphere growth-promoting bacteria strain Rm-FG10-5 is not less than 1×10⁻⁶. 8 CFU / mL. Preferably, the total viable count of the rhizosphere growth-promoting bacteria strain Rm-FG10-5 is 1–5 × 10⁻⁶. 8 CFU / mL. Preferably, the vegetable is cucumber, pepper, or tomato.

[0017] Based on the above method, the application is applied to the rhizosphere of the vegetable plants. Specifically, the vegetable seedlings are first soaked in water before transplanting, and then drenched in water within 20 days after transplanting; or the vegetable seedlings are drenched in water immediately after transplanting, and then drenched in water again 20 days after transplanting.

[0018] Therefore, the salt-tolerant rhizosphere growth-promoting bacterium Rm-FG10-5 provided by this invention exhibits strong salt tolerance, growing normally on both liquid and solid media with a high salt concentration of 16%, and still able to alleviate salt stress and promote plant growth under high salt stress conditions of 300 mmol / L NaCl solution. Furthermore, this strain also possesses the functions of protein decomposition, heparin production, and indoleacetic acid production. The Rm-FG10-5 strain has a stable colonization ability in plant roots and rhizosphere soil.

[0019] The method for promoting vegetable plant growth provided by this invention utilizes the salt-tolerant plant rhizosphere growth-promoting bacteria Rm-FG10-5 or its bacterial solution to soak the roots of vegetable seedlings, soak the roots of plants to be transplanted, and irrigate the rhizosphere soil of the transplanted plants. Because the Rm-FG10-5 strain can significantly increase the activity of antioxidant enzymes in plant roots, the expression level of antioxidant-related genes in plant roots, or the expression level of ion balance-related genes in plant roots, it can stably colonize in plant roots and rhizosphere soil, alleviate salt stress, improve root vitality, enhance the plant's resistance to adverse conditions, and promote plant growth, thereby achieving the goal of increasing yield and quality. Attached Figure Description

[0020] Figure 1 Figures show the cell morphology (A) and colony morphology (B) of Rm-FG10-5 bacteria;

[0021] Figure 2 This is a phylogenetic tree of Rm-FG10-5 constructed based on the 16S rRNA sequence;

[0022] Figure 3 Figure 1 shows the salt tolerance of strain Rm-FG10-5 in liquid culture (A) and solid culture medium (B).

[0023] Figure 4 A diagram illustrating the biological characteristics of strain Rm-FG10-5;

[0024] Figure 5 Diagram showing the colonization density of Rm-FG10-5 in the root system and rhizosphere soil of chili peppers;

[0025] Figure 6 The image shows the mitigation effect of Rm-FG10-5 on salt damage in chili seedlings;

[0026] Figure 7 The image shows the mitigation effect of Rm-FG10-5 on salt damage in cucumber seedlings.

[0027] Figure 8 The image shows the mitigation effect of Rm-FG10-5 on salt damage in tomato seedlings.

[0028] Figure 9 Figure showing the effect of Rm-FG10-5 on the activity of antioxidant enzymes in pepper roots;

[0029] Figure 10 The effect of Rm-FG10-5 on antioxidant genes in pepper roots is shown in the figure.

[0030] Figure 11 The effect of Rm-FG10-5 on genes related to ion balance in pepper roots is shown in the figure. Detailed Implementation

[0031] The technical solution of the present invention will be further described in detail below through specific embodiments.

[0032] Unless otherwise specified, all terms used in this invention are commonly used in the relevant field. The technical means employed in the embodiments, such as cultivation methods, identification methods, and testing methods, are all conventional methods well-known to those skilled in the art. All reagents and products used are commercially available. The source, trade name, and, where necessary, the components of the reagents are indicated upon their first appearance.

[0033] Example 1: Isolation and Screening of Rm-FG10-5 Strains

[0034] In August 2021, rhizosphere soil was collected from a field in Fugou County, Henan Province, where chili peppers had been continuously cropped for 5 years. The soil was mixed and cultured in 100 mL of sterile water for 30 minutes, then diluted 1000 to 10000 times with sterile water. The diluted mixture was evenly spread on TSA agar plates containing 10% NaCl and incubated upside down in a 28°C incubator for 48 to 72 hours. After colony formation, bacterial colonies of different sizes, colors, and morphologies were picked and purified by streaking on TSA agar plates containing 10% NaCl. Salt-tolerant bacteria were screened out. Then, a double-layer filter paper method was used: chili pepper seeds soaked in a suspension of salt-tolerant bacteria for 1 hour were placed on filter paper and covered with another layer of filter paper. The filter paper was moistened with 10 mL of 200 mmol / L NaCl solution and incubated in an incubator for 7 days. The root length of the chili pepper embryonic root was investigated to determine the mitigation effect on salt damage. The salt-tolerant plant rhizosphere bacteria strain Rm-FG10-5 was obtained. The Rm-FG10-5 strain was stored in an ultra-low temperature freezer at -80°C.

[0035] Example 2 Identification of Rm-FG10-5 strain

[0036] Morphological characteristics: Please refer to Figure 1 The cells of strain Rm-FG10-5 are rod-shaped. Figure 1 A), 0.5–0.8 μm in diameter and 2.5–3.2 μm in length, produces spores, is Gram-positive, and grows on nutrient broth (NA) medium as yellow, opaque, smooth, nearly circular colonies with relatively regular edges. Figure 1 B).

[0037] Physiological and biochemical characteristics: The physiological and biochemical characteristics of strain Rm-FG10-5 were identified by referring to the conventional bacteriological identification methods in Dong Xiuzhu's "Handbook for Systematic Identification of Common Bacteria". The results are shown in Table 1.

[0038] Table 1. Physiological and biochemical characteristics of strain Rm-FG10-5

[0039] Identification indicators Rm-FG10-5 Identification indicators Rm-FG10-5 Bacterial morphology rod-shaped maltose + Bacterial size 0.5~0.8μm × 2.5~3.2μm Tannic acid + Gram staining Positive Mannitol + Growth temperature range 5-45℃ Citric acid - Salt concentration ≤16％ nitrate reduction reaction - Glucose oxidation, fermentation, and motility Fermented type, sports type nitrite reduction reaction + sucrose + Gelatin liquefaction - glucose + <![CDATA[Production of H2S]]> - Galactose +

[0040] As shown in Table 1, the growth temperature range of Rm-FG10-5 strain is 5-45℃, the optimal growth temperature is 30℃, the maximum salt concentration tolerance is 16%, it can utilize sucrose, glucose, galactose, maltose, tannic acid and mannitol, but cannot utilize citric acid. It is positive for nitrite reduction, and negative for nitrate reduction, gelatin liquefaction and H2S reaction.

[0041] 16S rRNA sequence homology identification: The full-length 16S rRNA sequence of strain Rm-FG10-5 is 1457 bp, and it shares 99.72% homology with the 16S rRNA sequence of *Rosellomorea marisflavi*. A phylogenetic tree constructed based on the 16S rRNA sequence is shown below. Figure 2 As shown, from Figure 2 It can be seen that it clusters in one branch with Rossellomorea marisflavi (NR 025240.1).

[0042] Therefore, based on the colony morphology, physiological and biochemical characteristics, and molecular biological identification results of strain Rm-FG10-5, this strain is classified and named Rossellomorea marisflavi (Rm-FG10-5), and was deposited on July 3, 2024, at the China General Microbiological Culture Collection Center (CGMCC), located at No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing, with accession number CGMCC No. 31158.

[0043] Example 3: Biological functions of strain Rm-FG10-5

[0044] (1) Salt tolerance test: Rm-FG10-5 strain was inoculated onto TSB medium supplemented with NaCl and cultured at 28℃ with shaking for 48 hours. Growth of Rm-FG10-5 was then observed. Additionally, Rm-FG10-5 strain was inoculated onto TSA medium supplemented with NaCl and streaked. Growth of Rm-FG10-5 was then observed after 48 hours of incubation at 28℃. The NaCl concentrations in TSB and TSA media were 0%, 14%, and 16%, respectively. The results are as follows: Figure 3 As shown.

[0045] from Figure 3 As can be seen from A and 3B, strain Rm-FG10-5 has a strong salt tolerance and can grow normally on both liquid and solid media with a high salt concentration of 16%.

[0046] (2) Protein degradation performance was determined using the plate transparency method. Rm-FG10-5 strain was inoculated onto protein identification medium and incubated at 28℃ for 72 hours. The presence or absence of a transparency zone was then observed. The presence of a transparency zone indicated protein degradation. The results are as follows: Figure 4 As shown. The protein identification culture medium consists of 3.0 g casein, 5.0 g beef extract powder, 2.0 g sodium chloride, 0.05 g dipotassium hydrogen phosphate, 18 g agar and 1000 mL distilled water.

[0047] (3) The ferroptophilic production performance was determined using the clear zone method. Rm-FG10-5 strain was inoculated onto chromool CAS medium and cultured in a 28℃ incubator for 3–5 days. The presence or absence of a clear zone was observed; the presence of a clear zone indicated ferroptophilic production. The results were as follows: Figure 4 As shown.

[0048] (4) The performance of indoleacetic acid production was determined by using... Method of et al. (2011): Rm-FG10-5 strain was inoculated into LB broth supplemented with a final concentration of 100 mg / L tryptophan. After incubation at 28℃ and 160 rpm for 48–72 h, the culture was centrifuged at 10000 rpm for 5 min. 2 mL of the supernatant was collected and 4 mL of Salkawski chromogenic reagent (50 mL, 35% perchloric acid, 1 mL 0.5 M ferric chloride) was added. The mixture was allowed to react in the dark for 15–30 min, and the color change was observed. Results are as follows: Figure 4 As shown.

[0049] from Figure 4 It can be seen that the Rm-FG10-5 strain has the functions of decomposing proteins, producing heptaphiles and indoleacetic acid.

[0050] Example 4: Colonization ability of Rm-FG10-5 strain

[0051] This embodiment provides an Rm-FG10-5 bacterial suspension, comprising a concentration of 1×10⁻⁵. 8 The bacterial suspension was prepared using CFU / mL of Rm-FG10-5 strain and 0.075 mol / L magnesium sulfate. The preparation method included: inoculating Rm-FG10-5 strain into TSB medium, fermenting at 28℃ for 48 h to obtain the fermentation broth, centrifuging at 5000 rpm to obtain a precipitated bacterial block, and adding magnesium sulfate to it to obtain the Rm-FG10-5 bacterial suspension.

[0052] Population density was determined using a pot experiment: Healthy, uniformly grown pepper seedlings with 4-5 true leaves were transplanted into pots (9cm in diameter), and then irrigated with Rm-FG10-5 bacterial suspension (100mL / plant). The plants were then cultivated in a greenhouse. Roots and rhizosphere soil were collected every two days after treatment to determine the population density. Population density was determined using the dilution plating method. Pepper roots were washed in running water, 1g was cut, ground, and diluted with sterile water to measure root population density. 1g of rhizosphere soil was diluted with sterile water to measure rhizosphere soil population density. The root and rhizosphere soil dilutions were spread separately on TSA agar plates containing rifampicin and incubated at 28℃ for 48-72 hours until colonies formed. The colony count was then measured and the population density calculated. The results are shown below. Figure 5 As shown.

[0053] from Figure 5 It can be seen that strain Rm-FG10-5 has a stable colonization ability in the root system and rhizosphere soil of peppers, with a colonization density maintained at 102. 5 cfu / g and 10 6 CFU / g or higher.

[0054] Example 5: Effect of Rm-FG10-5 strain on alleviating salt stress

[0055] Healthy, uniformly growing pepper and tomato seedlings with 4-5 true leaves, and cucumber seedlings with 1-2 true leaves, were transplanted into flowerpots (9 cm in diameter). Each seedling was irrigated with 100 mL of the Rm-FG10-5 bacterial suspension provided in Example 4. After 24 hours, 100 mL of 300 mmol / L NaCl solution was irrigated, and after 3 days, 100 mL of 300 mmol / L NaCl solution was irrigated again. Water was used as a control, and each treatment was replicated in triplicate. The salt damage level was investigated after 15 days of cultivation in a greenhouse, and the salt damage index, mitigation effect, aboveground growth and chlorophyll content, root growth and root activity were calculated for pepper, cucumber, and tomato seedlings, respectively. The results are as follows: Figures 6-8 As shown in Tables 2-7.

[0056] Salt damage severity assessment grading standards: Grade 0: Normal plant growth, no symptoms of damage; Grade 1: Plant growth inhibited by 10%–30%, or bottom leaves showing reversible wilting or shedding, or a few plants with slight yellowing of cotyledons; Grade 2: Plant growth inhibited by 31%–50%, or lower leaves showing irreversible wilting; Grade 3: Plant growth inhibited by 51%–70%, or more than 1 / 2 of leaves showing irreversible wilting, shedding, or slight curling; Grade 4: Plant growth inhibited by 71%–90%, or more than 2 / 3 of leaves showing curling or shedding, or heart leaves curling; Grade 5: Plant growth completely inhibited, or all true leaves necrotic or shedding, or heart leaves necrotic.

[0057] Salt damage index = ∑(number of salt damage cases at each level × number of representative cases at each level) / (total number of surveys × highest representative value) × 100;

[0058] Relief effect (%) = (Control salt damage index - Treatment salt damage index) / Control salt damage index × 100.

[0059] Figures 6-8 The results showed that the chili pepper, cucumber, and tomato seedlings treated with clean water (CK) were significantly stunted, yellowed, and their leaves curled, fell off, and eventually died after salt stress treatment. The salt damage index of the chili pepper seedlings was 73.33, while the salt damage index of the chili pepper seedlings treated with Rm-FG10-5 was 30.95. The Rm-FG10-5 treatment achieved a 57.79% relief effect on salt stress in chili peppers; a 71.15% relief effect on salt stress in cucumbers; and a 46.73% relief effect on salt stress in tomatoes.

[0060] Table 2. Effects of Rm-FG10-5 on aboveground growth and chlorophyll content of pepper under salt stress.

[0061]

[0062] Table 3. Effects of Rm-FG10-5 on root growth and root activity of chili peppers under salt stress.

[0063]

[0064] Table 4. Effects of Rm-FG10-5 on aboveground growth and chlorophyll content of cucumber under salt stress.

[0065]

[0066] Table 5. Effects of Rm-FG10-5 on cucumber root growth and root activity under salt stress.

[0067]

[0068] Table 6. Effects of Rm-FG10-5 on aboveground growth and chlorophyll content of tomato under salt stress.

[0069]

[0070] Table 7. Effects of Rm-FG10-5 on root growth and root activity in tomato under salt stress.

[0071]

[0072] Tables 2-7 show that under salt stress, treatment with Rm-FG10-5 significantly promoted plant growth indicators such as plant height, stem diameter, fresh weight, and dry weight of peppers, cucumbers, and tomatoes, promoted root growth, improved root vitality, and increased chlorophyll content and chlorophyll fluorescence parameter Fv / Fm.

[0073] Example 6: Mechanism of action of strain Rm-FG10-5

[0074] Healthy chili seedlings with 4-5 true leaves of uniform growth were transplanted into flowerpots (9cm in diameter). The seedlings were then irrigated with the Rm-FG10-5 bacterial suspension provided in Example 4 (100mL / seedling). After 24 hours, 100mL of 300mmol / L NaCl solution was applied. After 24 hours of NaCl treatment, chili root samples were collected to determine the activity of antioxidant enzymes and the expression levels of antioxidant-related genes and ion balance-related genes. The results are as follows: Figures 9-11 As shown. Superoxide dismutase (SOD) activity was determined by the nitrogen-tetrazole photochemical reduction method, peroxidase (POD) activity was determined by the guaiacol method, catalase (CAT) activity was determined by the hydrogen peroxide method (Li Hesheng, 2000), and gene expression levels were determined by qRT-PCR analysis.

[0075] from Figure 9 It can be seen that Rm-FG10-5 treatment can increase the activity of antioxidant enzymes such as SOD, POD, CAT and APX in pepper roots. Figure 10 This indicates that increasing the expression levels of antioxidant-related genes and Figure 11 This shows the expression levels of genes related to ion balance in chili peppers.

[0076] Therefore, the Rm-FG10-5 strain can stably colonize the plant roots and rhizosphere soil. Based on the increased activity of antioxidant enzymes in the plant roots and the increased expression of antioxidant-related genes in the plant roots, it enhances the plant's resistance. Based on the increased expression of ion balance-related genes in the plant roots, it maintains the ion balance in the plant, exhibits high salt tolerance, alleviates salt stress, and improves the plant's stress resistance.

[0077] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them; although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications can still be made to the specific implementation of the present invention or equivalent substitutions can be made to some technical features without departing from the spirit of the technical solutions of the present invention, and all such modifications and substitutions should be covered within the scope of the technical solutions claimed in the present invention.

Claims

1. A rhizosphere growth-promoting bacterium for a salt-tolerant plant, characterized in that, The salt-tolerant plant rhizosphere growth-promoting bacteria are Rossellomorea marisflavi Rm-FG10-5, with accession number CGMCC No. 31158.

2. A bacterial solution of rhizosphere-promoting bacteria for salt-tolerant plants, characterized in that, Including the one described in claim 1 Rossellomorea marisflavi Rm-FG10-5 strain; the bacterial solution contained Rossellomorea marisflavi The concentration of Rm-FG10-5 is 1 to 5 × 10⁻⁵. 8 CFU / mL.

3. The rhizosphere growth-promoting bacterial solution for salt-tolerant plants according to claim 2, characterized in that, The bacterial solution also includes magnesium sulfate at a concentration of 0.05–0.1 mol / L.

4. A method for preparing the rhizosphere growth-promoting bacterial solution of salt-tolerant plants according to claim 2, comprising the step of: [preparing the solution of the bacteria described in claim 1]. Rossellomorea marisflavi The Rm-FG10-5 strain was inoculated into nutrient broth medium and fermented at 28-32 ℃ for 16-72 h.

5. The application of a rhizosphere growth-promoting bacterium for salt-tolerant plants as described in claim 1, or a bacterial solution of a rhizosphere growth-promoting bacterium for salt-tolerant plants as described in claim 2 or 3, in promoting salt tolerance in vegetables or alleviating salt stress; wherein, The vegetables mentioned are chili peppers, tomatoes, or cucumbers.

6. A method for promoting vegetable growth, comprising: Applying the salt-tolerant plant rhizosphere-promoting bacteria of claim 1 or the salt-tolerant plant rhizosphere-promoting bacteria solution of claim 2 or 3 to the rhizosphere of vegetable plants, wherein the... Rossellomorea marisflavi The total viable count of strain Rm-FG10-5 is not less than 1×10⁻⁵. 8 CFU / mL, wherein the vegetable is a chili pepper, tomato, or cucumber; The application involves first soaking the roots of the vegetable seedlings before transplanting, and then drenching them within 20 days after transplanting; or drenching the roots of the vegetable seedlings immediately after transplanting, and then drenching them again 20 days after transplanting.

7. The method according to claim 6, characterized in that, The Rossellomorea marisflavi The total viable count of strain Rm-FG10-5 was 1–5 × 10⁻⁵. 8 CFU / mL.

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