Growth-promoting and antibacterial microbial organic fertilizer for rice

Abstract

The invention relates to a growth-promoting and antibacterial microbial organic fertilizer for rice, which promotes absorption and utilization of plants to nitrogen and phosphorus nutrient elements by remarkably up-regulating expression of specific functional genes in the plants, enhances the disease resistance of the plants, and has a wide application prospect in agricultural production.

Description

Technical Field

[0001] This application belongs to the field of agricultural biotechnology, and particularly relates to a microbial organic fertilizer for promoting the growth and antibacterial activity of rice. Background Art

[0002] As one of the most important food crops in the world, the yield and quality of rice are directly related to human food security. With the continuous growth of the population and the increasing tension of arable land resources, improving the yield and disease resistance of rice has become an important topic in agricultural scientific research. Although the application of traditional chemical fertilizers can increase the rice yield in the short term, long-term excessive application will lead to problems such as soil compaction, fertility decline, and environmental pollution, which is not conducive to the sustainable development of agriculture. Therefore, it is particularly urgent to explore green, environmentally friendly, and efficient compound fertilizers (such as organic fertilizers and microbial fertilizers).

[0003] Traditional research has focused on the direct effects of compound fertilizers on plant growth phenotypes, and the effects may often vary due to the application of compound fertilizers to crops under different growth conditions. Without understanding the internal mechanisms of plant responses to fertilizers, such as which functional gene expressions are regulated by fertilizers, it is difficult to find the root causes of the differences in effects and impossible to quickly find solutions to problems. Studying the effects of compound fertilizers on plant gene regulation and analyzing phenotypic changes can deepen people's understanding of plant growth mechanisms, have more profound application values, and provide important theoretical support for precision agriculture, genetic engineering, and the sustainable development of agriculture.

[0004] There are thousands of functional genes in rice. Among them, the genes OsMGD2 and OsMGD3 encode monogalactosyldiacylglycerol synthase MGD, which are mainly involved in the synthesis of galactolipids (MGDG and DGDG) in non-photosynthetic tissues (such as roots and flowers), and can improve photosynthetic efficiency and biomass. The gene OsSAE1a is involved in the absorption, transport, and redistribution of phosphorus and nitrogen, and may play a key role in rhizosphere phosphorus activation and nitrogen assimilation. The gene OsSIZ2 regulates nitrogen metabolism-related genes (such as nitrate transporters and glutamine synthases), affecting nitrogen absorption, transport, and redistribution in the later growth stage. The gene OsNR1 encodes nitrate reductase, which is the core enzyme of nitrogen metabolism, catalyzes the conversion of nitrate to nitrite, and enhances the carbon-nitrogen synergistic efficiency. Summary of the Invention

[0005] To solve the above technical problems, this application first provides a strain of Pseudomonas sp. SJA1, which was deposited at the China General Microbiological Culture Collection Center on November 11, 2022, and the deposit number is: CGMCC No. 26128.

[0006] The present application also provides a biological agent, including one or more mixtures of the bacterial liquid, bacterial suspension, bacterial powder, fermentation product of the bacterium (such as fermentation broth), culture of the bacterium or filtrate of the culture, or metabolite of the Pseudomonas sp. SJA1 described above.

[0007] The present application also provides a composite flora, including the Pseudomonas sp. SJA1 and Bacillus megaterium JSY3 described above; the JSY3 was deposited at the General Microbiological Center of the China Committee for Culture Collection of Microorganisms on August 10, 2023, with the deposit number: CGMCC No. 28153 (CN117586914B). In some embodiments, SJA1 and JSY3 are mixed in equal proportions (such as 1:1), and the proportion can be a mass ratio or a volume ratio.

[0008] The present application also provides a biological agent, including the above-mentioned composite flora, and one or more mixtures of the bacterial suspension, metabolite of the flora, fermentation product of the bacterium (such as fermentation broth), culture of the bacterium or filtrate of the culture, or metabolite of the bacterium.

[0009] In some embodiments, the biological agent can be a suitable preparation such as a bacterial agent or a fertilizer. In some embodiments, the bacterial agent is an antibacterial agent (such as an antibacterial agent against Xanthomonas oryzae pv. oryzae); or the fertilizer is a compound fertilizer made of microbial bacterial fertilizer, organic fertilizer and / or inorganic fertilizer. In some specific embodiments, the fertilizer is a compound fertilizer prepared by mixing organic fertilizer and microbial bacterial fertilizer. In some specific embodiments, the fertilizer is a compound fertilizer prepared by mixing inorganic fertilizer and microbial bacterial fertilizer. In some specific embodiments, the compound fertilizer is directly applied to plants (such as rice). In some specific embodiments, the microbial bacterial fertilizer and other fertilizers (such as organic fertilizer or inorganic fertilizer) are applied to plants (such as rice) successively. In some specific embodiments, the application is root application or above-ground application (such as foliar spraying).

[0010] The present application also provides a bacterial agent, including the above-mentioned Pseudomonas or composite flora and acceptable auxiliaries.

[0011] In some embodiments, the auxiliaries are, for example, a culture medium suitable for the growth of the composite flora or a microbial protectant, etc.

[0012] Examples of the microbial protectant are alginate oligosaccharide, arctium oligosaccharide, vegetable oil, ectoine, fumaric acid, etc.

[0013] The present application also provides a method for upregulating the expression levels of OsMGD2, OsMGD3, OsSIZ2, OsSAE1a, and / or OsNR1 genes in plants, or a method for promoting plant growth, or a method for promoting nitrogen and phosphorus accumulation in plants, or a method for promoting resistance to Xanthomonas oryzae pv. oryzae in plants, including applying a composite bacterial community or applying a biological agent containing the composite bacterial community; the composite bacterial community includes a strain of Pseudomonas sp. SJA1 and Bacillus megaterium JSY3; SJA1 was deposited at the General Microbiology Center of the China Microbial Culture Collection Center on November 11, 2022, with the deposit number: CGMCC No. 26128; JSY3 was deposited at the General Microbiology Center of the China Microbial Culture Collection Center on August 10, 2023, with the deposit number: CGMCC No. 28153.

[0014] In some embodiments, the OsMGD2, OsMGD3, OsSIZ2, OsSAE1a, and / or OsNR1 genes are located in the leaves or roots of plants.

[0015] In some embodiments, promoting plant growth is promoting the biomass of the above-ground and underground parts of plants.

[0016] In some embodiments, the biomass of the above-ground and underground parts includes one or more of plant height, fresh weight or dry weight of leaves, and fresh weight or dry weight of roots.

[0017] In some embodiments, promoting nitrogen and phosphorus accumulation in plants is promoting nitrogen and phosphorus accumulation in the leaves and roots of plants.

[0018] In the art, obtaining a bacterial solution, bacterial suspension, bacterial powder, fermentation product of bacteria (such as fermentation broth), culture of bacteria or filtrate of the culture, or metabolite of bacteria of a single bacterium or a composite bacterial community is a conventional technique. Nevertheless, the present application still gives some examples: The activated strains SJA1 and JSY3 are respectively inoculated into a liquid medium for culture to obtain single-bacterium bacterial solutions; after centrifuging these bacterial solutions, they are resuspended with sterile water to obtain single-bacterium bacterial suspensions; the bacterial cells obtained after centrifuging these bacterial solutions or bacterial suspensions are dried and ground into powder to obtain single-bacterium bacterial powders; SJA1 and JSY3 are respectively or simultaneously inoculated into a fermentation medium for fermentation to obtain a single-bacterium fermentation broth or a fermentation broth of a composite bacterium; the single-bacterium bacterial solutions or single-bacterium bacterial suspensions of the two strains SJA1 and JSY3 are mixed in equal volume, or the single-bacterium bacterial powders of the two strains are mixed in equal mass to obtain a composite bacterium agent or a biological agent. The composite bacterium agent or biological agent can be a solid product or a liquid product.

[0019] Microbial bacterial fertilizer: includes the above-mentioned Pseudomonas or composite bacterial community.

[0020] The present application also provides a compound fertilizer prepared using the above-mentioned biological agent.

[0021] The present application also provides a fertilizer prepared using the above-mentioned Pseudomonas or complex bacterial community. In some embodiments, the fertilizer is a compound fertilizer. In some embodiments, the fertilizer includes the above-mentioned microbial fertilizer, organic fertilizer, and / or inorganic fertilizer.

[0022] In some embodiments, the inorganic fertilizer is inorganic nitrogen fertilizer, inorganic phosphorus fertilizer, and / or inorganic potassium fertilizer. In some embodiments, the inorganic nitrogen fertilizer includes urea and / or ammonium sulfate; in some embodiments, the inorganic phosphorus fertilizer includes monoammonium phosphate and / or diammonium phosphate; in some embodiments, the inorganic potassium fertilizer includes potassium sulfate and / or potassium chloride.

[0023] The present application also provides an antibacterial agent prepared using the above-mentioned biological agent, such as an antibacterial agent for resisting Xanthomonas oryzae pv. oryzae.

[0024] Since the genes OsMGD2, OsMGD3, OsSIZ2, OsSAE1a, or OsNR1 are ubiquitous in plant tissues and have similar functions, the research results on the expression of these genes in the present application are expected to be extended to more plant types other than rice. The plant can be a monocotyledonous plant or a dicotyledonous plant, a herbaceous plant or a woody plant, a crop (such as rice), a vegetable plant, or a fruit plant, etc.

[0025] The present application also provides an application of the above-mentioned bacteria, complex bacterial community, bacterial agent, complex bacterial agent, biological agent, the above-mentioned compound fertilizer, or the above-mentioned antibacterial agent in the field of agricultural planting, especially in the planting of crops (such as rice), vegetables, or fruits.

[0026] The present application also provides a plant growth promoter prepared from the above-mentioned bacteria, complex bacterial community, bacterial agent, complex bacterial agent, biological agent, the above-mentioned compound fertilizer, or the above-mentioned antibacterial agent. The uses of plant growth promotion include, for example, promoting the biomass of the above-ground and underground parts of rice.

[0027] In some embodiments, the biomass of the above-ground and underground parts is at least one of the following: plant height, fresh weight or dry weight of leaves, fresh weight or dry weight of roots.

[0028] The present application also provides an application of the above-mentioned biological agent, the above-mentioned compound fertilizer, or the above-mentioned antibacterial agent in increasing the expression levels of the genes OsMGD2, OsMGD3, OsSIZ2, OsSAE1a, and / or OsNR1 in rice leaves and roots.

[0029] The present application also provides an application of the above-mentioned biological agent, the above-mentioned compound fertilizer, or the above-mentioned antibacterial agent in promoting the nitrogen and phosphorus accumulation amounts in rice leaves and roots.

[0030] The present application also provides the use of the above-mentioned biological agent, the above-mentioned compound fertilizer, or the above-mentioned antibacterial agent in promoting rice resistance to Xanthomonas oryzae pv. oryzae. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 : Plant height of rice under different treatments.

[0032] Figure 2 : Fresh weight and dry weight of rice leaves under different treatments.

[0033] Figure 3 : Fresh weight and dry weight of rice roots under different treatments.

[0034] Figure 4 : Nitrogen and phosphorus accumulation in rice leaves under different treatments.

[0035] Figure 5 : Nitrogen and phosphorus accumulation in rice roots under different treatments.

[0036] Figure 6 : Relative expression levels of the OsMGD2 gene in rice leaves and roots under different treatments.

[0037] Figure 7 : Relative expression levels of the OsMGD3 gene in rice leaves and roots under different treatments.

[0038] Figure 8 : Relative expression levels of the OsSIZ2 gene in rice leaves and roots under different treatments.

[0039] Figure 9 : Relative expression levels of the OsSAE1a gene in rice leaves and roots under different treatments.

[0040] Figure 10 : Relative expression levels of the OsNR1 gene in rice leaves and roots under different treatments.

[0041] Figure 11 : Determination of the growth ability of Xanthomonas oryzae pv. oryzae after JS and MC treatments. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0042] To specifically illustrate the general design concept of the present application, only rice is taken as an example for display below, but it should not be used as a reason to limit the protection scope of the present application.

[0043] Unless otherwise specified, the experimental methods used in the following examples are all conventional methods. Unless otherwise specified, the materials, reagents, etc. used in the following examples can all be obtained from commercial channels.

[0044] Example 1 Experimental Design

[0045] I. Experimental Materials:

[0046] Rice variety: Huruang 1212 was selected, which is a common rice variety in this region and has certain representativeness and adaptability.

[0047] Soil: The soil used in the experiment was taken from the paddy soil of the CK in the large field treatment of Qingpu Modern Agricultural Park to ensure consistent soil background and reduce the impact of soil differences on the experimental results. The basic physical and chemical properties of the soil were as follows: Before the experiment, the basic physical and chemical properties of the soil were total nitrogen 1.70 g·kg -1 , total phosphorus 0.95 g·kg -1 , available potassium 0.11 g·kg -1 , organic matter 29.60 g·kg -1 , pH was 7.02.

[0048] Organic fertilizer: Provided by Qingpu Modern Agricultural Park, rich in various organic matters and nutrient elements, providing basic nutrients for rice growth.

[0049] Bacterial fertilizer: ① Compound bacteria (fertilizer): SJA1 Pseudomonas and JSY3 were used in combination to explore their synergistic effects. ② Commercial Bacillus (fertilizer) and commercial Pseudomonas (fertilizer): Commercially available products, used as a comparison to evaluate the relative advantages of compound bacterial fertilizers.

[0050] II. Experimental design: In this study, the method of pot experiment was adopted, with 7 different treatment combinations set, and 3 replicates were set for each treatment, totaling 21 pots. Specifically as follows:

[0051] Blank treatment (CK): Applied the organic fertilizer from Qingpu Modern Agricultural Park as the control group to evaluate the relative effects of other treatments.

[0052] Bacterial fertilizer treatment (JS): Applied the organic fertilizer from Qingpu Modern Agricultural Park, and at the same time added JSY3 (CGMCC No.28153) Bacillus megaterium bacterial fertilizer and SJA1 (CGMCC No.26128) Pseudomonas bacterial fertilizer, aiming to explore the growth-promoting effect of compound bacterial fertilizer.

[0053] Bacterial fertilizer treatment (JC): Applied the organic fertilizer from Qingpu Modern Agricultural Park, combined with JSY3 Bacillus megaterium and commercial Pseudomonas to compare the differences between compound bacterial fertilizer and commercial bacterial fertilizer.

[0054] Bacterial fertilizer treatment (SC): Applied the organic fertilizer from Qingpu Modern Agricultural Park, combined with the purchased commercial Bacillus fertilizer and SJA1 Pseudomonas to further compare the effects of different bacterial fertilizer combinations.

[0055] Bacterial fertilizer treatment (MC): Applied the organic fertilizer from Qingpu Modern Agricultural Park, added the purchased commercial Bacillus fertilizer and commercial Pseudomonas as the representative treatment of commercial bacterial fertilizer.

[0056] Bacterial fertilizer + Xanthomonas oryzae pv. oryzae treatment (JS+B): On the basis of the bacterial fertilizer treatment (JS), inoculate with Xanthomonas oryzae pv. oryzae to evaluate the disease resistance effect of the compound bacterial fertilizer.

[0057] Bacterial fertilizer + Xanthomonas oryzae pv. oryzae treatment (MC+B): On the basis of the bacterial fertilizer treatment (MC), inoculate with Xanthomonas oryzae pv. oryzae to compare the disease resistance capabilities of different bacterial fertilizer treatments.

[0058] Experimental method of Example 2

[0059] The collected fresh soil was naturally air-dried after manually removing residues, and then screened through a 20-mesh sieve to remove larger particles and impurities. Select white plastic buckets as the potting containers, with a bottom diameter of 13.5 cm and a height of 16 cm. Before transplanting rice, according to the treatment groups, each bucket was filled with 1.5 kg of sieved dry soil and thoroughly mixed with organic fertilizer. The application rate of the organic fertilizer was converted according to the standard of 240 kg·hm-2 N to ensure the consistency of nutrient supply among different treatments. After potting, water was applied 1 day in advance to make the soil fully absorb water and reach an appropriate moisture state. For rice transplanting, select rice seedlings with consistent growth and good health for transplanting, with 3 plants in 1 hole per pot. During transplanting, pay attention to keeping the root systems of the seedlings intact to avoid damage, so as to facilitate their rapid recovery of growth in the pots.

[0060] The activated strains JSY3 and SJA1 were inoculated into LB liquid medium and placed on a shaker for culturing at a speed of 140 revolutions per minute for 24 h. Then, 3 liters of LB liquid medium was prepared and sterilized to ensure the sterility of the culture environment. Subsequently, 50 ml of the bacterial liquid was taken, added to 3 liters of LB liquid medium, and then transferred to a fermenter for further shaking culture. In the fermenter, the bacterial liquid was cultured under suitable conditions for three days to promote the large-scale proliferation of the strains. After the fermentation culture was completed, the bacterial liquid was poured into a sterile bottle for subsequent use. According to a 1:1 ratio, JSY3 was mixed with SJA1, JSY3 was mixed with commercial Pseudomonas, and SJA1 was mixed with commercial Bacillus. 25 ml of the mixed bacterial liquid was watered on each rice plant, and it was watered twice, on the first day and the seventh day after rice transplanting respectively.

[0061] Disease inoculation: When the rice grew to an appropriate stage (about two weeks after transplanting), for the JS+B and MC+B treatments, the spray inoculation method was used to evenly spray the Xanthomonas oryzae pv. oryzae bacterial liquid with OD600 = 1.5 on the rice leaves. Observation was carried out three days later and samples were taken for determination of the bacterial growth ability.

[0062] During the entire growing season, no drainage is carried out, and the water layer height in the pot is always maintained at 1 - 3 cm. Regularly check the moisture status of the potted plants and replenish water in a timely manner to meet the water requirements for rice growth. Regularly record the growth status of rice and check the occurrence of rice diseases, and take pictures to record the leaf morphology, so as to analyze the growth and development of rice subsequently, calculate the disease index according to the degree of disease occurrence, and evaluate the disease resistance effects of different treatments.

[0063] When the experiment reaches the tillering stage of rice potted plants, collect rice samples. Rice leaves and roots are used to analyze the nitrogen and phosphorus contents in the plants and detect the expression of nitrogen and phosphorus-related genes by qPCR technology, providing basic data for in-depth research.

[0064] Determination of physical and chemical properties of roots and leaves: Total phosphorus is determined by the molybdenum antimony anti-colorimetric method; total nitrogen is determined by the Kjeldahl method.

[0065] Study on the expression of functional genes in roots and leaves: Use the plant rapid extraction kit of Beijing BestGene Biotechnology Co., Ltd. to extract total RNA from rice leaves and roots, detect the concentration of RNA using a NanoDrop2000 spectrophotometer, and then perform quality detection of total RNA by agarose gel electrophoresis. Take 0.5 - 1 μg of total RNA to reverse transcribe into cDNA, and use cDNA as a template to perform qRT-PCR to determine the relative expression levels of nitrogen and phosphorus-related genes. The reaction system is 20 μl, and the reaction program is: 95°C for 30 s; 95°C for 10 s; 60°C for 30 s; 40 cycles. Each sample is repeated 3 times for qRT-PCR. The relative gene expression levels are calculated using the 2-ΔΔCt method, with OsActin and OsUbq as internal reference genes.

[0066] Method for measuring the growth ability of bacteria: Resuspend the bacterial solution with 10 mM MgCl2 and dilute it to make the OD600 of the bacterial solution = 0.2. Dilute the bacterial solution with an OD600 of 0.2 by 1000 times. Put the removed rice leaves into 1.2 ml of 10 mM MgCl2 solution, add 3 sterilized small steel beads, place the sample in an automatic sample grinder for grinding, each time for 30 s, with a frequency of 50 Hz, repeat six times. After grinding, take 40 μl of the bacterial solution and add it to 160 μl of 10 mM MgCl2 solution for dilution, and repeat gradient dilution until the bacterial concentration is convenient for counting. Pipette 10 μl of each concentration of the bacterial solution and drop it on the NA medium. After there is no obvious liquid on the medium, seal the medium and place it in an incubator at 28°C for 40 h. The number of bacteria is expressed by colony-forming units CFU. Select the concentration gradient with CFU in the range of 20 - 100 for counting, and set three replicates for the bacterial solution of each concentration gradient.

[0067] Rice disease statistics method: 15 days after spray inoculation, the diseased area of rice leaves is statistically analyzed. At least 15 leaves of each rice plant are statistically analyzed, and they are classified and recorded according to the degree of the diseased area of the leaves. According to the survey results, the disease index of rice is calculated. Disease index = [(number of diseased leaves at each level * relative level value) / (total number of surveyed leaves * 11)] * 100.

[0068] Example 3 Growth situation of rice and response situation of functional genes OsMGD2 and OsMGD3 I. Influence on functional genes:

[0069] Relative expression levels of OsMGD2 gene under different treatments: As Figure 6 can be seen, in leaves, the relative expression levels of OsMGD2 gene are relatively high in both JSY3 + SJA1 treatment and SJA1 + commercial bacteria treatment, significantly higher than that in commercial bacterial fertilizer treatment. In roots, the relative expression level of OsMGD2 gene is also the highest in JSY3 + SJA1 treatment, and the relative expression level of SJA1 + commercial bacteria treatment is also significantly higher than that of commercial bacterial fertilizer.

[0070] Relative expression levels of OsMGD3 gene under different treatments: As Figure 7 can be seen, in leaves, the expression level of OsMGD3 gene is the highest in JSY3 + SJA1 treatment, significantly higher than that in commercial bacterial fertilizer treatment, and the relative expression levels of JSY3 + commercial bacteria and SJA1 + commercial bacteria are also significantly higher than that in commercial bacterial fertilizer treatment. In roots, the relative expression level of JSY3 + SJA1 treatment is also the highest, significantly higher than other treatments.

[0071] II. Influence on rice growth:

[0072] Plant height of rice under different treatments: As Figure 1 shown, among all treatments, the plant height of JS treatment is the longest, which is 36.4 cm. The JS treatment and SC treatment are significantly higher than other groups; the plant height of JC treatment is the shortest, which is 22.9 cm, slightly lower than that of CK treatment. The JS treatment significantly promotes the growth of rice seedlings. The promotion of plant height by JC, SC, and MC treatments is not as good as that of JS treatment. Among them, the comparison between JS treatment and MC treatment shows extremely significant difference, indicating that the growth promotion effect of JS treatment on rice seedlings is significantly better than that of MC treatment.

[0073] Fresh weight and dry weight of rice leaves under different treatments: As Figure 2 can be seen, the fresh weight and dry weight of rice leaves in JS treatment are significantly higher than other groups, indicating that the JS treatment has a significant growth promotion effect on rice leaves. The fresh weight and dry weight of rice leaves in CK treatment are the lowest, serving as the control group. The fresh weight and dry weight of rice leaves in JC, SC, and MC treatments are higher than those in CK treatment, but lower than those in JS treatment, indicating that the growth promotion effect of commercial bacterial fertilizer on plants is not as good as that of JS treatment. There is a significant difference between JS treatment and MC treatment.

[0074] Fresh and dry weights of rice roots under different treatments: As can be seen from Figure 3 , in terms of fresh and dry weights of roots, the JS treatment is higher than other groups and significantly higher than the CK treatment, indicating that the JS treatment has the best growth-promoting effect on rice roots. The fresh weight of rice roots in the JC treatment is similar to that of CK, while the dry weight is significantly higher than that of the CK treatment; the fresh and dry weights of rice roots in the SC treatment are higher than those of the CK treatment but lower than those of the JS treatment; the fresh and dry weights of rice roots in the MC treatment are similar to those of CK, indicating that the commercial bacterial fertilizer has no obvious growth-promoting effect on rice roots, and the application of JSY3 or SJA1 bacteria combined with the commercial bacteria can still show a growth-promoting effect. There is a highly significant difference between the JS treatment and the MC treatment.

[0075] Example 4 Nitrogen and phosphorus accumulation in rice and the responses of functional genes OsSIZ2, OsSAE1a, and OsNR1

[0076] I. Effects on functional genes:

[0077] Relative expression levels of the OsSIZ2 gene under different treatments: As can be seen from Figure 8 , in leaves, the relative expression level of the OsSIZ2 gene is the highest in the JSY3 + commercial bacterial fertilizer treatment, significantly higher than that in the commercial bacterial fertilizer treatment. Among them, the relative expression level in the JSY3 + SJA1 treatment is also significantly higher than that in the commercial bacterial fertilizer treatment. In roots, the expression level of the OsSIZ2 gene is the highest in the JSY3 + SJA1 treatment, significantly higher than other treatments.

[0078] Relative expression levels of the OsSAE1a gene under different treatments: As can be seen from Figure 9 , in leaves, the relative expression levels of the OsSAE1a gene are the highest in the JSY3 + SJA1 treatment and the SJA1 + commercial bacteria treatment, significantly higher than other treatments. In roots, the relative expression level of the OsSAE1a gene in the JSY3 + commercial bacteria treatment is significantly higher than that in other treatment groups, and there is no significant difference between the JSY3 + SJA1 treatment and the commercial bacterial fertilizer treatment.

[0079] Relative expression levels of the OsNR1 gene under different treatments: As can be seen from Figure 10 , in leaves, the relative expression level of the OsNR1 gene is the highest in the SJA1 + commercial bacteria treatment, significantly higher than other treatments, and the relative expression level of the gene in the JSY3 + SJA1 treatment is significantly higher than that in the commercial bacterial fertilizer treatment. In roots, the relative expression level of the gene in the SJA1 + commercial bacteria treatment is the highest, significantly higher than the relative expression levels of the commercial bacterial fertilizer treatment and CK.

[0080] II. Nitrogen and phosphorus accumulation in rice:

[0081] Nitrogen and phosphorus accumulation amounts in rice leaves under different treatments: As can be seen from Figure 4It can be seen that the highest nitrogen and phosphorus accumulation in leaves was observed in the JS treatment, far higher than that in other treatments, showing significant differences. The nitrogen and phosphorus accumulation in leaves of the CK treatment was the lowest, serving as the control group. The nitrogen accumulation in leaves of the MC treatment was higher than that of the CK treatment; while the phosphorus accumulation in leaves of the JC, SC, and MC treatments was significantly higher than that of the CK treatment. This indicates that commercial organic bacterial fertilizers can promote the nitrogen and phosphorus accumulation in rice leaves, but not as effectively as the JS treatment, which significantly increases the nitrogen and phosphorus accumulation in rice leaves.

[0082] Nitrogen and phosphorus accumulation in the roots of rice under different treatments: From Figure 5 It can be observed that the highest nitrogen and phosphorus accumulation in the roots of rice was in the JS treatment, showing significant differences. The nitrogen and phosphorus accumulation in the roots of the CK and MC treatments was relatively low. The nitrogen and phosphorus accumulation in the roots of the JC and SC treatments was higher than that of the CK and MC treatments, but lower than that of the JS treatment. This indicates that commercial bacterial fertilizers may have an obvious effect on the nitrogen and phosphorus accumulation in the roots of rice, but the increase in the nitrogen and phosphorus accumulation in the roots is not obvious. There are significant differences between the JS treatment and other treatments. In the JC and SC treatments, it may be due to the combination of commercial bacteria with the JSY3 or SJA1 bacteria in this study, showing the ability to increase the nitrogen and phosphorus accumulation in the roots of rice.

[0083] Example 5 Disease resistance of rice

[0084] Through the experiment of inoculating Xanthomonas oryzae pv. oryzae and measuring the growth ability of Xanthomonas oryzae pv. oryzae after the JS and MC treatments, it can be seen from Table 1 and Figure 11 that the growth quantity of Xanthomonas oryzae pv. oryzae in the MC treatment was extremely significantly higher than that in the JS (JSY3 + SJA1) treatment. This indicates that the compound bacterial fertilizer has a significant effect on enhancing the disease resistance of rice.

[0085] Table 1 Results of Xanthomonas oryzae pv. oryzae disease index

[0086]

[0087] In summary, the combined application of organic fertilizer and microbial bacterial fertilizer can significantly improve the growth index and nutrient element content of rice, and at the same time enhance the disease resistance of rice. In particular, the JS treatment group has significant advantages in promoting rice growth and increasing nutrient element content.

[0088] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Thus, if these modifications and variations of this application fall within the scope of the claims of this application and their equivalent technologies, this application is also intended to include these modifications and variations.

Claims

1. A strain of Pseudomonas sp. SJA1, characterized in that: The SJA1 was deposited in the General Microbiology Center of China Microorganism Culture Collection Administration on November 11, 2022, with the deposit number: CGMCC No.26128.

2. A biological agent, characterized in that: The method comprises one or more mixtures of a bacterial liquid, a bacterial suspension, a bacterial powder, a bacterial fermentation product, a bacterial culture or a filtrate of the culture, or a bacterial metabolite of the Pseudomonas sp. SJA1 according to claim 1.

3. The biological agent according to claim 2, characterized in that The biological agent is a bacterial agent or a fertilizer.

4. The biological agent according to claim 3, characterized in that The bacterial agent is an antibacterial agent; or the fertilizer is a compound fertilizer made of microbial fertilizer, organic fertilizer and / or inorganic fertilizer.

5. A composite bacterial community, comprising Pseudomonas sp. SJA1 and Bacillus megaterium JSY3 described in claim 1; the JSY3 was deposited in the General Microbiology Center of China National Microbiological Culture Collection Administration on August 10, 2023, with the deposit number: CGMCC No.28153.

6. The composite bacterial flora according to claim 5, characterized in that The ratio of the Pseudomonas sp. SJA1 to the Bacillus megaterium JSY3 is 1:

1.

7. A biological agent, characterized in that: The invention comprises the composite bacterial community as claimed in claim 5 or 6, and a bacterial suspension of the bacterial community, a bacterial metabolite, a bacterial fermentation broth, a bacterial culture or a filtrate of the culture, or one or more mixtures of bacterial metabolites.

8. The biological agent according to claim 6, characterized in that The biological agent is a bacterial agent or a fertilizer.

9. The biological agent according to claim 7, characterized in that The bacterial agent is an antibacterial agent; or the fertilizer is a composite bacterial fertilizer made of microbial fertilizer, organic fertilizer and / or inorganic fertilizer.

10. The antibacterial agent according to claim 4 or claim 9, characterized in that It is an antibacterial agent against bacterial blight.

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