A strain of Paracoccus maseri, a salt-tolerant growth-promoting agent and its application

Abstract

This invention discloses a strain of *Paragonimus masculinus*, a salt-tolerant growth-promoting bacterial agent, and their applications, belonging to the field of microbial technology. This invention screened a strain of *Paragonimus masculinus* CZJ5 that promotes plant growth and enhances plant salt stress tolerance. It is deposited at the China General Microbiological Culture Collection Center (CGMCC) with accession number CGMCC No. 36255. Experimental results show that *Paragonimus masculinus* CZJ5 possesses salt tolerance characteristics and functions such as nitrogen fixation, phosphorus solubilization, silicate solubilization, and siderophore production. It can effectively promote the absorption and utilization of nitrogen, phosphorus, and iron by plants, thereby promoting plant growth. *Paragonimus masculinus* CZJ5 significantly enhances the growth of wild barley plants under salt stress and their salt tolerance. This invention provides a new growth-promoting bacterial agent for improving plant salt tolerance and offers a new technical means for crop cultivation in saline-alkali land.

Description

Technical Field

[0001] This invention relates to the field of microbial technology, and in particular to a strain of Paracoccus martensii, a salt-tolerant growth-promoting agent, and their applications. Background Technology

[0002] Soil salinity in agricultural soils refers to the high concentration of soluble salts in the root soil moisture. These soluble salts create high osmotic pressure, which limits plant water absorption and the balanced absorption of basic nutrient ions by the roots, thus affecting plant growth. The formation of saline-alkali land is the result of multiple factors, commonly including long-term over-cultivation leading to soil structure damage, excessive fertilization causing salt accumulation in the soil, and drought causing groundwater salts to rise to the surface with evaporation. The most direct impact of soil salinization is reduced grain yields; annual crop failures due to salinization threaten food security. Improving and rationally utilizing saline-alkali land can not only transform previously low-yield "stagnant soil" into arable land but also directly increase the cultivated land area, playing an irreplaceable role in ensuring stable food supply and maintaining ecological security.

[0003] Beneficial microbial communities in microbial inoculants, through a series of decomposition and synthesis processes such as nitrogen fixation and phosphorus solubilization, can transform soil substances into various nutrients, improving soil fertility and promoting plant growth. Beneficial microorganisms can also secrete various antibiotics and other antibacterial substances, inhibiting the growth and reproduction of pathogens, inducing systemic disease resistance in plants, reducing disease occurrence, and enhancing plant stress resistance. In recent years, the application of microbial technology in saline-alkali soil remediation has received increasing attention and strengthening, mainly focusing on research into enhancing plant salt and alkali tolerance through microorganisms. Existing studies have found that salt-tolerant microorganisms can improve the rhizosphere environment of plants, reduce the inhibitory effect of salt on crop growth, and achieve the goal of improving saline-alkali soil. Studies have also found that strains can promote the emergence rate, increase biomass, and reduce disease incidence of mung beans under NaCl stress. Therefore, microbial activity can, to a certain extent, improve the survival rate and retention rate of vegetation in saline-alkali soils, playing an important role in the long-term improvement of saline-alkali soils, restoring soil physicochemical properties, and reconstructing the ecological environment of saline-alkali soils. Summary of the Invention

[0004] The purpose of this invention is to provide a strain of Paracoccus martensii, a salt-tolerant growth-promoting agent, and their applications to solve the problems existing in the prior art. Paracoccus martensii CZJ5 has a significant effect on improving the growth of wild barley plants under salt stress and the ability of wild barley plants to tolerate salt stress. This invention provides a new growth-promoting agent for improving the salt tolerance of plants and provides a new technical means for the cultivation of crops in saline-alkali land.

[0005] To achieve the above objectives, the present invention provides the following solution:

[0006] This invention provides a Paracoccus marcusii CZJ5 strain, which has been deposited at the China General Microbiological Culture Collection Center (CGMCC) with accession number CGMCC No. 36255, deposited on October 20, 2025, at the Institute of Microbiology, Chinese Academy of Sciences, No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing.

[0007] The present invention also provides the application of the above-mentioned Paracoccus martensii CZJ5 in the preparation of growth-promoting agents that improve the salt stress tolerance of plants.

[0008] The present invention also provides a growth-promoting agent, with the above-mentioned Paracoccus martensii CZJ5 as the active ingredient.

[0009] Furthermore, the growth-promoting agent has an absorbance of not less than 0.6 at a wavelength of 600 nm.

[0010] The present invention also provides the use of the above-mentioned Paracoccus martensii CZJ5 or the above-mentioned growth-promoting agent in any of the following:

[0011] (1) Desilicates;

[0012] (2) Iron-producing carrier.

[0013] The present invention also provides the application of the above-mentioned Paracoccus martensii CZJ5 or the above-mentioned growth-promoting agent in promoting plant growth.

[0014] The present invention also provides a method for promoting plant growth, comprising the step of applying the above-mentioned Paracoccus martensii CZJ5 or the above-mentioned growth-promoting bacterial agent to the plant growth environment.

[0015] The present invention also provides the application of the above-mentioned Paracoccus martensii CZJ5 or the above-mentioned growth-promoting agent in improving the salt stress tolerance of plants.

[0016] The present invention also provides a method for improving the salt stress tolerance of plants, comprising the step of applying the above-mentioned Paracoccus martensii CZJ5 or the above-mentioned growth-promoting bacterial agent to the plant growth environment.

[0017] Furthermore, the plant grows in a saline environment.

[0018] The present invention discloses the following technical effects:

[0019] This invention screened a strain of *Paragonimus masculinii* CZJ5 that promotes plant growth and enhances plant salt stress tolerance. It is deposited at the China General Microbiological Culture Collection Center (CGMCC) with accession number CGMCC No. 36255. Experimental results show that *Paragonimus masculinii* CZJ5 possesses salt tolerance characteristics and functions such as nitrogen fixation, phosphorus solubilization, silicate solubilization, and siderophore production. It can effectively promote the absorption and utilization of nitrogen, phosphorus, and iron by plants, thereby promoting plant growth. *Paragonimus masculinii* CZJ5 significantly enhances the growth of wild barley plants under salt stress and their salt tolerance. This invention provides a new growth-promoting bacterium for improving plant salt tolerance and offers a new technical means for crop cultivation in saline-alkali land. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a colony morphology diagram of Paracoccus maltii CZJ5.

[0022] Figure 2 Phylogenetic tree diagram of Paracoccus martensii CZJ5;

[0023] Figure 3 The growth curves of Paracoccus martensii CZJ5 at different salt concentrations are shown.

[0024] Figure 4 Plate dissolution zone for phosphate solubilization of Paracoccus maseri CZJ5;

[0025] Figure 5 Plate dissolution zone for silicate hydrolysis of Paracoccus maseri CZJ5;

[0026] Figure 6 Plate dissolution zone of Paracoccus maseri CZJ5 as an iron-producing carrier;

[0027] Figure 7 The figure shows the phenotypic observation results of the effect of Paracoccus martensii CZJ5 on the growth of wild barley under saline-alkali or non-saline-alkali conditions.

[0028] Figure 8 This is a statistical chart showing the effects of Paracoccus martensii CZJ5 on the plant height, root length, dry weight, and fresh weight of wild barley under saline-alkali or non-saline-alkali conditions.

[0029] Preservation Information: Paracoccus marcusii CZJ5 has been deposited at the China General Microbiological Culture Collection Center (CGMCC) with accession number CGMCC No. 36255, deposit date October 20, 2025, and address: Institute of Microbiology, Chinese Academy of Sciences, No. 3, No. 1 Beichen West Road, Chaoyang District, Beijing. Detailed Implementation

[0030] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0031] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0032] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0033] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0034] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0035] LB solid medium: tryptone 10 g / L, yeast extract 5 g / L, sodium chloride 10 g / L, agar 18 g / L, pH adjusted to 7.0-7.2.

[0036] LB liquid medium: yeast extract 5 g / L, tryptone 10 g / L, NaCl 10 g / L, pH adjusted to 7.

[0037] Nitrogen-fixing medium (nitrogen-free medium): mannitol 10.0 g / L, CaCO3 5 g / L, KH2PO4 0.2 g / L, MgSO4·7H2O 0.2 g / L, NaCl 0.2 g / L, CaSO4·2H2O 0.2 g / L, agar 20 g / L, pH adjusted to 7.0-7.2.

[0038] Monkina Organic Phosphorus Solid Medium: Glucose 10.0 g / L, yeast extract 0.4 g / L, (NH4)2SO4 0.5 g / L, MnSO4·4H2O 0.03 g / L, KCl 0.3 g / L, FeSO4·7H2O 0.03 g / L, NaCl 0.3 g / L, CaCO3 5 g / L, egg yolk lecithin 0.2 g / L, agar 20 g / L, pH adjusted to 7.0.

[0039] Silicate-solubilizing bacteria culture medium: sucrose 5.0 g / L, MgSO4 0.5 g / L, CaCO3 0.1 g / L, Na2HPO4 2.0 g / L, FeCl3 0.005 g / L, glass powder 1.0 g / L, agar 15.0 g / L, pH adjusted to 7.0-7.2.

[0040] CAS detection medium: Chromium azurite S (CAS) 60.5 mg / L, hexadecyltrimethylammonium bromide 72.9 mg / L, FeCl3·6H2O 2.645 mg / L, NaH2PO4·2H2O 295.25 mg / L, Na2HPO4·12H2O 1213.5 mg / L, NH4Cl 125.0 mg / L, KH2PO4 37.5 mg / L, NaCl 62.5 mg / L, agar 9000.0 mg / L, pH adjusted to 6.7-6.9.

[0041] Example 1: Isolation and Identification of Growth-Promoting Bacterial Strains

[0042] 1. Sample collection

[0043] Soil samples were collected from saline-alkali soil in Linze County, Zhangye City, Gansu Province. The soil collection method adopted was a five-point sampling method. Five sampling points were determined in the selected area. Soil samples of 10-20 cm were collected from saline-alkali soil of different degrees. Equal amounts of soil were collected from each point, mixed, and then placed in sterile bags and sealed. The collection number, collection location, date and other key information were marked. The samples were brought back to the laboratory and stored at 4℃.

[0044] 2. Soil sample enrichment treatment

[0045] Soil samples were sieved through a 20-mesh sieve (approximately 1 mm in diameter). 10 g of the sample was weighed and placed in an Erlenmeyer flask containing 90 mL of sterile aqueous solution (containing 10-15 sterile glass beads). The flask was incubated at 28°C and 150 rpm for 2-3 hours, then allowed to stand for 10 minutes to obtain a soil suspension diluted 10 times. This suspension was recorded as 10 g. -1 Diluent. Use a pipette to draw 1 mL of 10... -1 Add the diluent to a test tube containing 9 mL of sterile water, mix well by pipetting, and dilute to a 10:1 ratio. -2 Diluent, then dilute in the same manner to prepare 10. -3 10 -4 10 -5 10 -6 10 -7 Prepare a series of gradient dilutions; take 0.1 mL of each gradient dilution and spread it evenly on LB agar plates, repeating each concentration in 3 plates, and incubate the plates upside down in a 28℃ incubator for 2-3 days.

[0046] 3. Strains Isolation and Screening

[0047] Select plates with suitable colony density (30-300 / plate), pick single colonies of different types from the above LB agar plates and streak them onto LB agar plates for isolation, incubate at 28℃ for 2-3 days, pick single cells again for streaking, and repeat the single cell streaking 2-3 times to obtain single cell pure cultures of each strain; pick single cells of each strain and inoculate them into LB liquid medium, incubate at 28℃ and 150 rpm for 12-24 hours, and screen for strains that show obvious growth in the medium for strain purification and preservation.

[0048] 4. Strain purification and preservation

[0049] The pure bacterial culture was cryopreserved in 30% glycerol at low temperature. The culture was named L172.

[0050] Example 2 Morphological identification of growth-promoting bacterial strains

[0051] The purified strain L172 was selected and cultured on LB agar using the streak plating method at 28°C for 2 days. Colony morphology was then observed; the colony morphology of the growth-promoting bacteria is shown below. Figure 1 As shown.

[0052] The colonies of the growth-promoting bacteria strain L172 are smooth, with neat, slightly raised edges and a glossy appearance.

[0053] Example 3 Molecular biological identification and preservation of growth-promoting bacterial strains

[0054] The isolated and purified strain L172 was subjected to molecular biological identification. This was achieved through DNA extraction, PCR amplification, and 16S rRNA gene sequencing.

[0055] Forward primer 27F: 5'-AGAGTTTGATCCTGGCTCAG-3', SEQ ID NO.1;

[0056] Reverse primer 1492R: 5'-TACGGCTACCTTACGACTT-3', SEQ ID NO.2.

[0057] The PCR product of the amplified 16S rRNA was sent to Sangon Biotech (Shanghai) Co., Ltd. for sequencing.

[0058] By performing nucleic acid sequence homology alignment (Blastn) in the GenBank database on NCBI, strain L172 was preliminarily identified as Paracoccus sp.

[0059] Phylogenetic tree comparison results showed that strain L172 is evolutionarily close to several species in the genus *Paracoccus*, especially *Paracoccus marcusii*. This further validated the preliminary identification results based on 16S rRNA gene sequencing and homology comparison, namely that strain L172 belongs to *Paracoccus marcusii* of the genus *Paracoccus*. This provides important taxonomic basis for further in-depth research and application development of this strain. Figure 2 As shown.

[0060] Paracoccus marcusii L172 has been renamed CZJ5. Paracoccus marcusii CZJ5 is deposited at the China General Microbiological Culture Collection Center (CGMCC) with accession number CGMCC No. 36255, deposited on October 20, 2025, at the Institute of Microbiology, Chinese Academy of Sciences, No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing.

[0061] Example 4: Salt tolerance of Paracoccus martensii CZJ5

[0062] Preparation of seed culture: A single colony of Paracoccus martensii CZJ5 was picked and inoculated into a test tube of LB liquid medium and cultured at 28℃ and 180 rpm for 24 h to prepare the mycelial seed culture.

[0063] Saline-alkali culture media (NaCl:Na2SO4=1:1) containing mass concentrations of 0 mmol / L, 200 mmol / L, 400 mmol / L, 600 mmol / L, and 800 mmol / L were prepared. *Paragonimus malathi* CZJ5 seed culture was inoculated at a 3% inoculum and cultured for 40 h. The growth curves of *Paragonimus malathi* CZJ5 at different salt concentrations were then determined.

[0064] Growth curves as follows Figure 3 As shown. By Figure 3 It can be seen that: as the salt concentration in the culture medium increases, the time required for *Paragonimus westermani* CZJ5 to enter the logarithmic phase increases; the CZJ5 strain exhibits the best growth at a salt concentration of 200 mmol / L, entering the logarithmic phase after 2 hours of culture and reaching its peak after 24 hours; the CZJ5 strain can tolerate a salt concentration of 400 mmol / L, and at this concentration, the bacterial concentration OD200 reaches a stationary phase. 600 With a value above 0.6, it can be concluded that *Paragonimus westermani* CZJ5 can grow normally in culture media with salt concentrations not exceeding 400 mmol / L, maintaining stable viability and tolerance. Furthermore, *Paragonimus westermani* CZJ5 can also grow at salt concentrations of 600 mmol / L and 800 mmol / L, indicating that it can grow and reproduce normally in high-salt concentration culture media, maintaining its viability. This demonstrates that *Paragonimus westermani* CZJ5 can adapt to high-salt, high-osmotic-pressure environments, opening up a wider range of applications, such as the biological treatment of high-salt wastewater and the improvement of saline-alkali soils.

[0065] Example 5: Nitrogen fixation, phosphorus solubilization, silicate solubilization, and siderogenic characteristics of Paracoccus martensii CZJ5

[0066] 1. Nitrogen fixation detection experiment

[0067] Nitrogen-free medium test: Pick a small number of single colonies of Paracoccus martensii CZJ5, streak them on a nitrogen-free medium plate, and observe whether the strain can grow and form colonies on the nitrogen-free medium.

[0068] Nitrogenase activity assay (acetylene reduction method): Seed culture of *Paracoccus malathi* CZJ5 was inoculated into LB liquid medium at a 3% inoculum volume and cultured at 28°C and 180 rpm with shaking for 24 h. The culture was then transferred to centrifuge tubes and centrifuged at 4°C and 8000 rpm for 10 min to collect the bacterial cells. The cells were washed 2-3 times with physiological saline and resuspended to adjust the OD concentration. 600 =1.0, prepare a bacterial suspension; take 1 mL of bacterial suspension and add it to a centrifuge tube containing 9 mL of nitrogen-free medium and react for 1 h and send it to Shanghai Zhuocai Biotechnology Co., Ltd.; the nitrogenase activity of Paracoccus martensii CZJ5 of the present invention is 74.7471 nmol / (mL×h).

[0069] This indicates that the fermentation products of Paracoccus martensii CZJ5 have high nitrogenase activity.

[0070] 2. Detection experiment of dissolved phosphorus (organic phosphorus)

[0071] Take 5 μL of *Paragonimus westermani* CZJ5 seed culture and spot it onto the center of a Monkina organophosphate medium plate. Repeat the process three times and incubate at 28°C for 3-5 days. Observe whether a clear zone is formed around the colony.

[0072] The results are as follows Figure 4 As shown, Paracoccus martensii CZJ5 produces a clear zone of phosphorus solubilization on organic phosphorus culture medium, indicating that Paracoccus martensii CZJ5 has a significant effect on solubilizing organic phosphorus.

[0073] 3. Silicate detection experiment

[0074] Take 5 μL of Paracoccus martensii CZJ5 seed culture and spot it onto the center of a silicate-solubilizing bacteria agar plate. Repeat 3 times and incubate at 28℃ for 3-5 days. Observe whether oil droplets are produced around the colonies.

[0075] The results are as follows Figure 5 As shown, Paracoccus martensii CZJ5 can produce oil droplets on silicate-solubilizing bacteria culture medium, indicating that Paracoccus martensii CZJ5 has obvious silicate-solubilizing properties.

[0076] 4. Experiment on the characteristics of iron-producing carriers

[0077] Take 5 μL of Paracoccus martensii CZJ5 seed culture and spot it onto the center of a CAS detection medium plate. Repeat the process 3 times and incubate at 28℃ for 3-5 days. Observe whether an orange-yellow halo appears around the colony.

[0078] The results are as follows Figure 6 As shown, Paracoccus maseri CZJ5 produces a yellow halo on the siderogenic detection medium, indicating that Paracoccus maseri CZJ5 has siderogenic properties.

[0079] In summary, the *Paracoccus martensii* CZJ5 isolated by this invention possesses the characteristics of nitrogen fixation, phosphorus solubilization, silicate solubilization, and acting as a iron-carrier strain. It can promote the decomposition and transformation of nutrients (nitrogen, phosphorus, silicates, and iron) in the soil, which is beneficial for promoting the absorption of nutrients by plants.

[0080] Example 6: Paracoccus martensii CZJ5 promotes the growth of wild barley

[0081] Simulated saline-alkali planting system: A mixed salt solution was added to the loess culture system to simulate the saline-alkali planting environment, and the growth-promoting effect of Paracoccus martensii CZJ5 on the seedling growth of wild barley was verified by an experiment.

[0082] (1) Disinfect the surface of wild barley seeds, soak them in 95% alcohol for 2 min, stir them in 1% sodium hypochlorite solution for 3 min, rinse them 10 times with sterile water, keep them moist, germinate them in the dark at 25℃ for 2 days, and select germinated seeds with a sprout length of about 1 cm for sowing.

[0083] (2) Select seeds with relatively uniform sprout length after germination and sow them in loess pots. Inoculate and do not inoculate the seeds, with 9 seedlings planted for each treatment. A salt-free control system was also set up, and inoculate and do not inoculate the seeds in the same way. After sowing, wild barley was conventionally cultivated until the seedling stage.

[0084] (3) Experimental strain: Paracoccus martensii CZJ5; LB liquid medium, 28℃, 180 rpm, cultured for 36 h; the bacterial suspension was centrifuged at 8000 rpm for 10 min to obtain bacterial cells, washed once with physiological saline and then resuspended, and the OD was adjusted. 600 Within the range of 0.6-0.8, the inoculation amount is 50 mL / pot, and it is repeated twice every 3 days.

[0085] A control group was set up by watering wild barley plants with 50 mL of sterile water per pot.

[0086] (4) Prepare salt solutions with salt concentrations of 0 mmol / L, 200 mmol / L, 400 mmol / L, 600 mmol / L, and 800 mmol / L (NaCl:Na2SO4=1:1). After adding the bacterial culture, add 50 mL of salt solution per basin each time.

[0087] After treatment, the plants were placed in a smart greenhouse and given appropriate water every two days. After 7 days of cultivation, the plant height, fresh weight, dry weight, and root length of wild barley seedlings were measured to evaluate the effect of Paracoccus martensii CZJ5 on the growth phenotype of wild barley.

[0088] The results are as follows Figure 7 and Figure 8 As shown. According to Figure 7 It was found that under normal conditions (0 mmol / L saline solution), the barley plants treated with CZJ5 (L172) had significantly higher plant height than the control group. The control group of barley plants with saline solution concentrations greater than 200 mmol / L all showed obvious wilting, yellowing, and reduced plant height, while the barley plants treated with CZJ5 (L172) exhibited significantly better phenotypes than the control group plants at the corresponding concentrations.

[0089] according to Figure 8It can be seen that under normal conditions (0 mmol / L salt solution) and salt stress conditions, the wild barley plants inoculated with CZJ5 (L172) had better plant height, root length, fresh weight and dry weight than the control group wild barley plants with the corresponding salt solution concentration.

[0090] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A type of Paracoccus martensii ( Paracoccus marcusii CZJ5, characterized in that, The Paracoccus martensii CZJ5 has been deposited at the China General Microbiological Culture Collection Center (CGMCC) with accession number CGMCC No. 36255, deposited on October 20, 2025, at the Institute of Microbiology, Chinese Academy of Sciences, No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing.

2. The application of *Paragonimus westermani* CZJ5 as described in claim 1 in the preparation of a growth-promoting bacterial agent to improve plant salt stress tolerance, characterized in that... The plant in question is wild barley.

3. A growth-promoting agent, characterized in that, The active ingredient is Paracoccus martensii CZJ5 as described in claim 1.

4. The growth-promoting bacterial agent as described in claim 3, characterized in that, The growth-promoting agent has an absorbance of not less than 0.6 at a wavelength of 600 nm.

5. The use of the *Paragonimus westermani* CZJ5 according to claim 1 or the growth-promoting agent according to claim 3 or 4 in any of the following: (1) Desilicates; (2) Iron-producing carrier.

6. The application of *Paragonimella maltii* CZJ5 as described in claim 1 or the growth-promoting agent as described in claim 3 or 4 in promoting plant growth, characterized in that... The promotion of plant growth refers to promoting the growth of wild barley in a saline-alkali planting environment.

7. A method for promoting plant growth, characterized in that, The step includes applying the Paracoccus martensii CZJ5 of claim 1 or the growth-promoting bacterial agent of claim 3 or 4 to the plant growth environment; The promotion of plant growth refers to promoting the growth of wild barley in a saline-alkali planting environment.

8. The application of the *Paragonimus malathi* CZJ5 as described in claim 1 or the growth-promoting agent as described in claim 3 or 4 in improving the salt stress tolerance of wild barley.

9. A method for improving the salt stress tolerance of wild barley, characterized in that, The method includes the step of applying the Paracoccus martensii CZJ5 of claim 1 or the growth-promoting agent of claim 3 or 4 to the wild barley growing environment.

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