Plant growth-promoting rhizosphere strain dy58 and application thereof

Abstract

The invention relates to the technical field of microorganisms, and particularly discloses a plant growth-promoting rhizosphere strain dy58 and application thereof. The plant growth-promoting rhizosphere bacterial strain dy58 is preserved in the China General Microbiological Culture Collection Center on March 26, 2024, the classification name of the plant growth-promoting rhizosphere bacterial strain dy58 is Pseudomonas resinovorans, and the preservation number of the plant growth-promoting rhizosphere bacterial strain dy58 is CGMCC No.30150. The plant growth-promoting rhizosphere bacterial strain dy58 can be used for preparing the plant growth-promoting rhizosphere bacterial strain dy58. The strain dy58 has high siderophore secretion capacity and is widely applied as an agricultural soil inoculant. In a water culture experiment, the growth speed, the leaf chlorophyll content and the overground part fresh weight of the plant can be effectively improved by exogenously applying an inoculation bacterium liquid preparation of the strain dy58. In a pot experiment, when an inoculation bacterium liquid preparation of the strain is externally applied, the growth speed, the leaf chlorophyll content and the single plant yield of plants can be effectively increased, the Fe and Zn contents of potato blocks are increased, and the quality of the potato blocks is improved.

Description

Technical Field

[0001] The present invention belongs to the field of microbial technology, and particularly relates to a plant growth promoting rhizobacterium dy58 and its uses. Background Art

[0002] Potato ( Solanum tuberosum L. ) is one of the important food crops globally. Its tubers are rich in carbohydrates, proteins, vitamins, and mineral elements, and are the main food source in many regions. However, during the growth process of potato, the absorption efficiency of mineral elements such as iron (Fe) and zinc (Zn) is relatively low. Especially when the availability of these elements in the soil is insufficient, it is likely to lead to a decrease in potato yield and quality. Iron and zinc are essential micronutrients for plant growth and development, and are involved in various physiological metabolic processes, such as photosynthesis, respiration, and enzyme activity regulation. The deficiency of iron and zinc not only affects plant growth, but also causes a decrease in the content of mineral elements in tubers, thereby affecting their nutritional value and edible quality.

[0003] Traditionally, chemical fertilizers are applied to supplement iron and zinc elements in the soil, but this method has problems such as high cost, low utilization rate, and environmental pollution. In addition, the long-term use of chemical fertilizers may cause negative impacts such as soil compaction and microbial community imbalance. Therefore, it is crucial to develop an efficient microbial fertilizer suitable for potato and utilize it reasonably.

[0004] Plant growth promoting rhizobacteria (PGPR) are a group of microorganisms growing in the rhizosphere of plants, which can promote crop growth through direct and indirect mechanisms. PGPR provide the three basic essential macronutrients required by plants, namely nitrogen, phosphorus, and potassium, through nitrogen fixation, phosphorus solubilization, and potassium solubilization, directly increasing the content of nutrient elements in the soil and promoting the nutrient absorption and growth and development of plants. In addition, PGPR synthesize different plant hormones and other molecules, such as indole-3-acetic acid (IAA), cytokinins, gibberellins, and siderophores, etc., to antagonize plant pathogens and enhance the disease resistance of the host. PGPR can help plants absorb elements such as iron and zinc in the soil more effectively and convert them into forms that can be utilized by plants. This effect can not only increase the yield of crops, but also increase the nutritional value of crops.

[0005] Under natural conditions, the rhizosphere environment of plants is intricate. The inoculated microbial inoculants can be regarded as "invaders" and have to withstand multiple environmental stresses. They must compete for ecological niches with populations in the native microbial community, and only by successfully colonizing can they exert their efficacy. There is a series of special bacterial communities naturally present in the soil microbial community, which can adapt to extreme environments and win in the competition for the same ecological niche, thereby helping plants resist adversity.

[0006] Screening and identifying PGPR strains with high-efficiency siderophore secretion ability and other plant growth-promoting characteristics from potato rhizosphere, and developing microbial fertilizers suitable for potatoes can not only improve the absorption efficiency of mineral elements such as iron and zinc by potatoes, but also promote plant growth, increase yield and improve tuber quality. This method has the advantages of environmental friendliness, strong sustainability, low cost, etc., meeting the needs of the green development of modern agriculture. Therefore, screening and developing high-efficiency PGPR strains and their fertilizer products suitable for potatoes is of great significance for solving the problem of low absorption efficiency of mineral elements by potatoes, and also provides a reference for the development of microbial fertilizers for other crops.

[0007] Pseudomonas resinovorans ( Pseudomonas resinovorans ) is an aerobic Gram-negative bacterium of the genus Pseudomonas. It has been reported that Pseudomonas resinovorans has a high-efficiency degradation effect on aliphatic ester pollutants and can convert pollutants into harmless substances such as CO2 and H2O relatively completely. It can be used to repair the pollution of aliphatic ester pollutants in environmental media such as polluted water bodies and polluted soils. There are literature reports that Pseudomonas resinovorans can be used to produce a long-chain dibasic acid (DCn), an important chemical intermediate. There are also literature reports that Pseudomonas resinovorans can be used to produce borneol dehydrogenase (PrBDH). However, there are few reports on the promotion of plant growth by Pseudomonas resinovorans. Summary of the Invention

[0008] The object of the present invention is to provide a plant growth-promoting rhizobacterium dy58 and its uses in view of the above deficiencies of the prior art. The strain dy58 is a Pseudomonas resinovorans with good siderophore secretion ability. Through experiments, it has been found that it has an obvious promoting effect on potato growth and has prospects in potato cultivation and the application of agricultural soil inoculants.

[0009] To achieve the above object, the present invention adopts the following technical solutions: The first aspect of the present invention is to provide a plant growth-promoting rhizobacterium dy58, which was deposited with the China General Microbiological Culture Collection Center on March 26, 2024, and is classified and named Pseudomonas resinovorans Pseudomonas resinovorans , and the deposit number is CGMCC No. 30150.

[0010] The second aspect of the present invention is to provide a microbial agent, which contains the above-mentioned plant growth-promoting rhizobacterium dy58.

[0011] Further, the microbial agent is a microbial agent for promoting plant growth and / or a microbial agent for improving soil.

[0012] Further, the improvement of the soil is manifested as the production of siderophores.

[0013] Furthermore, the promotion of plant growth is embodied in all or part of the following: increasing the plant height growth rate, the chlorophyll content in plant leaves, the yield per plant, and / or the iron and zinc contents in plant fruits.

[0014] Furthermore, the plant is a potato.

[0015] The third aspect of the present invention is to provide the application of the above-mentioned plant rhizosphere growth-promoting strain dy58 or the microbial agent, including any of the following applications: A1) Application in improving soil; A2) Application in promoting plant growth; A3) Application in siderophore production; A4) Application in preparing products for siderophore production.

[0016] Furthermore, the promotion of plant growth is embodied in all or part of the following: increasing the plant height growth rate, the chlorophyll content in plant leaves, the yield per plant, and / or the iron and zinc contents in plant fruits, and the plant is a potato.

[0017] The fourth aspect of the present invention is to provide a method for promoting plant growth, including the following steps: applying the above-mentioned plant rhizosphere growth-promoting strain dy58 or the microbial agent to plant plants, plant seeds, or plant rhizosphere soil.

[0018] The fifth aspect of the present invention is to provide a method for improving soil, including the following steps: applying the above-mentioned plant rhizosphere growth-promoting strain dy58 or the above-mentioned microbial agent to the soil to be improved; the improvement of the soil is embodied as siderophore production.

[0019] Compared with the prior art, the beneficial effects brought by the technical solution provided by the present invention are as follows: The plant rhizosphere growth-promoting strain dy58 screened by the present invention has a high siderophore secretion ability and has broad application prospects as an agricultural soil inoculant. In the hydroponic experiment, the inoculation bacterial liquid preparation of strain dy58 applied exogenously can effectively increase the plant growth rate, the chlorophyll content in leaves, and the fresh weight of the above-ground part. In the pot experiment, the inoculation bacterial liquid preparation of this strain applied exogenously can effectively increase the plant growth rate, the chlorophyll content in leaves, the yield per plant, increase the Fe and Zn contents in potato tubers, and improve the quality of potato tubers. Description of the Drawings

[0020] Figure 1 It is a light yellow transparent circle diagram of strain dy58 on CAS medium; Figure 2 It is a colony diagram of strain dy58 on TSA medium; Figure 3It is the microscopic examination picture (10×100) of the colony of strain dy58; Figure 4 It is the electrophoresis result picture of the PCR product of the 16S rDNA of strain dy58; Note: M is the Maker DNA DL2000 marker (the band distribution of DL2000: 2000, 1000, 750, 500, 250, 100 bp), and 1 and 2 are the PCR products; Figure 5 It is the phylogenetic evolution tree diagram of dy58 based on the 16S rDNA sequence; Figure 6 It is the annotation analysis diagram of the homologous protein cluster (COG) of the whole genome sequencing of strain dy58; Figure 7 It is the gene ontology annotation (GO annotation) analysis diagram of the whole genome sequencing of strain dy58; Figure 8 It is the KEGG annotation analysis diagram of the whole genome sequencing of strain dy58; Figure 9 It is the virulence factor analysis diagram of the whole genome sequencing of strain dy58; Figure 10 It is the drug resistance gene analysis diagram of the whole genome sequencing of strain dy58; Figure 11 It is the annotation diagram of the core synthesis genes of the siderophore of the whole genome sequencing of strain dy58; Figure 12 It is the growth situation picture of the whole plant in the control group in hydroponics in Example 2; Figure 13 It is the growth situation picture of the whole plant of the experimental group of DES plants inoculated with strain dy58 in hydroponics in Example 2; Figure 14 It is the comparison picture of the growth situation of the whole plant of the experimental group and the control group of DES plants inoculated with strain dy58 in potting in Example 3. Specific implementation manners

[0021] To make the objectives, technical solutions and advantages of the present invention clearer, the following further describes the specific implementation manners of the present invention in detail in combination with specific embodiments and drawings. For those not specified in the embodiments in terms of specific technologies or conditions, they shall be carried out according to the technologies or conditions described in the literature in the field or according to the product specifications. For reagents or instruments not specified in terms of the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0022] Example 1 Isolation, identification and preservation of the plant growth-promoting rhizobacterium dy58.

[0023] 1. Isolation, purification and screening of the plant growth-promoting rhizobacterium dy58 The effective nutrient element content in the rhizosphere soil of potatoes with relatively low content was obtained by the random sampling method in Dayao County, Yunnan Province (25.85°N, 101.25°E). The collected rhizosphere soil was resuspended with sterile water and diluted at a 10-fold gradient. At a dilution concentration of 1×10 -4 the soil suspension was evenly spread on TSA medium, and single colony strains were isolated and purified. The single colony strains were inoculated onto CAS solid medium, and the strains with effects were selected to further repeat the siderophore production experiment.

[0024] The preparation method of the medium used in the process of strain isolation, purification and screening is as follows: Tryptic Soy Broth Medium (TSB Medium): 30 g / L of TSB, and adding 15 g / L of agar is Tryptic Soy Agar Medium (TSA Medium).

[0025] CAS Medium: 30 g / L of TSA medium, adding 10×CAS detection solution sterilized by filtration.

[0026] Determination of the siderophore secretion ability of the plant growth-promoting rhizobacteria strain dy58.

[0027] Qualitative determination of the siderophore secretion ability of strain dy58: The test strains were inoculated on CAS solid medium after overnight culture and activation, and inoculated three times repeatedly. After the bacterial liquid on the solid plate medium was air-dried, it was statically cultured at 30°C for 2 d. Since the iron ions in the plate were competitively chelated by the siderophores secreted by the strains, the original bright blue chelate showed a light yellow color due to the loss of iron ions. The strength of the siderophore secretion ability of the strain was calculated according to the ratio (D / d) of the diameter (D) of the light yellow halo to the diameter (d) of the colony. The diameter of the light yellow halo and the diameter of the transparent dissolution-promoting circle were accurately measured and the dissolution-promoting index SI was calculated.

[0028] SI = diameter D (mm) of the light yellow halo / diameter d (mm) of the colony Figure 1 The siderophore secretion ability of strain dy58 is shown. After inoculation on CAS solid medium and static culture for 2 d, a light yellow halo can be produced, indicating that this strain has the ability to secrete siderophores. The size of the light yellow halo was measured by the cross method, and the ratio D / d of the diameter (D) of the light yellow halo to the diameter (d) of the colony was calculated to be 2.87 ± 0.38, indicating that strain dy58 has a strong siderophore secretion ability.

[0029] Quantitative determination of the siderophore secretion ability of strain dy58: After the tested strain was activated by overnight culture, it was inoculated on TSB liquid medium, inoculated in triplicate, and cultured in a shaker at 180 rpm at 30 °C for 48 h. The culture solution was centrifuged at 12,000 rpm for 5 min to collect the supernatant. Using 3 mL of distilled water as a control for zero adjustment, 3 mL of the supernatant was taken as the experimental group, and 3 mL of the TSB medium without inoculated strain was taken as the control group. An equal volume of CAS color reagent was added, and after mixing, it was left to stand in the dark for 30 min. Measure the absorbance value (As) of the experimental group and the absorbance value (Ar) of the control group at 630 nm, and calculate the relative content of siderophore in the culture solution according to the following formula.

[0030] Relative content of siderophore (%) = [(Ar - As) / Ar] × 100% After measurement, the As value was 1.204 and the Ar value was 1.616. After calculation, the relative content of siderophore in the culture solution of strain dy58 was 25.50%. Strain dy58 has a strong ability to secrete siderophores.

[0031] A bacterium was isolated and purified from the potato rhizosphere soil sample collected from Dayao County, Yunnan Province by the dilution coating plate method, the plate streaking method and the determination of siderophore secretion ability, and named dy58. It has a high ability to secrete siderophores.

[0032] 2. Strain identification 2.1 Identification of the bacterial morphology and physiological and biochemical characteristics of strain dy58 Refer to the "Common Bacteria System Identification Manual" and the "Bergey's Manual of Determinative Bacteriology" to observe and describe the colony morphology, color and physiological and biochemical determination of strain dy58.

[0033] Colony morphology: Figure 2 This is the colony morphology of strain dy58 on TSA medium. The colonies of strain dy58 are light yellow opaque colonies, with a smooth surface, slightly convex in the middle, and regular colony edges. Figure 3 This is the colony morphology of strain dy58 observed under an optical microscope. Strain dy58 is a rod-shaped bacterium with a straight or slightly curved shape.

[0034] Physiological and biochemical characteristics: Strain dy58 is Gram-negative, with a capsule and no endospores.

[0035] 2.2 Molecular identification of strain dy58 The genomic DNA of strain dy58 was extracted as a PCR template, and universal primers for bacterial 16S rDNA were used. Their sequences are shown in SEQ ID NO: 2 and SEQ ID NO: 3, 27F: 5'-AGAGTTTGATCCTGGCTCAG-3', 1492R: 5'-TACGGCTACCTTGTTACGACTT-3', perform PCR amplification. Figure 4 The PCR products shown were sent to Majorbio Bio-Pharm Technology Co., Ltd. for sequencing after being detected by gel electrophoresis. The raw sequences at both ends obtained by Sanger sequencing were respectively subjected to quality control to remove low-quality bases. After obtaining the clean sequences, they were assembled to obtain the assembled sequence, and the species with the highest similarity obtained by blasting against the NT database was used as the result of bacterial identification. And the 16S rDNA gene sequences of closely related species within the same genus were selected for homology analysis, and a phylogenetic tree was constructed using MEGA 11.0, as Figure 5 shown.

[0036] 2.3, Whole genome analysis of strain dy58 Strain culture collection: The test strain was cultured overnight for activation. A single colony was picked and inoculated into 500 mL of TSB medium, and cultured overnight at 30 °C with 220 rpm. When the OD 600 value was 0.5 - 0.7, the cells were collected by centrifugation at 5000 rpm for 10 min. The cells were washed twice with sterile 0.9% NaCl solution and collected. The cell weight reached 0.5 - 1.0 g. After the collected cells were quickly frozen in liquid nitrogen, they were transported at low temperature with dry ice and sent to Majorbio Bio-Pharm Technology Co., Ltd. for whole-genome sequencing of the strain. The company's sequencing strategy was to use a method that combines the second-generation (Illumina Hiseq) sequencing and the third-generation (PacBio) sequencing for complementary sequencing. The preliminary sequencing results were quality-corrected using GC-depth distribution analysis, K-mer frequency distribution analysis, and genome coverage analysis to obtain the complete chromosomal and plasmid sequences. Further, COG, GO, KEGG annotations, and predictions of virulence genes, drug resistance genes, and siderophore genes were carried out.

[0037] COG (clusters of orthologous groups of proteins) annotation: COG can predict and classify the functions of individual microbial proteins and the proteins in the complete genome through phylogenetic relationships. Figure 6 It shows that a total of 5420 proteins of strain dy58 were functionally annotated by COG, accounting for 96.83% of all its genes. The number of genes with the annotation functions of amino acid transport, metabolic gene transcription, and general function prediction were 603, 503, and 457 respectively. In addition, 413 signal transduction mechanism function genes and 310 inorganic ion transport and metabolism function genes were annotated.

[0038] GO (Gene Ontology) Annotation: GO is an internationally standardized gene function classification system, which is divided into three ontologies, namely molecular function, cellular component, and biological process, to describe the functions of genes. Each gene corresponds to one or more GO functions. GO annotation can be used to annotate the genes in the whole genome of a strain, verify the known functions of the strain, and discover unknown hidden functions. Figure 7 It shows that 3,317 genes in strain dy58 are annotated by GO, accounting for 67.23% of all genes. Among them, 2,613, 1,612, and 1,603 genes are annotated to molecular function, cellular component, and biological process respectively, accounting for 78.77%, 48.59%, and 48.32% of all GO-annotated genes. Among them, 296 genes are annotated to functions related to metal ion binding, and 71 genes are annotated to zinc ion binding.

[0039] KEGG (Kyoto Encyclopedia of Genes and Genomes) Annotation: The KEGG database is often used to comprehensively understand the cell metabolic pathways of the secreted products of a strain and the functional roles of gene metabolites. Figure 8 It shows that the genes annotated in strain dy58 fall into six major categories: cellular processes, environmental information processing, genetic information processing, human diseases, metabolism, and organismal systems. A large number of genes are enriched in environmental response. In dy58, 245 membrane transport genes and 248 signal transduction genes are enriched.

[0040] Prediction of Virulence Genes: Microorganisms can invade and attach to specific host plants through specific virulence genes and virulence factors, thus forming an interaction microenvironment between microorganisms and host plants. Figure 9 It shows that a total of 747 virulence genes are annotated in dy58. Virulence factors can be divided into four major categories: offensive, defensive, non-specific, and conventional virulence factors. Among them, there are 145 genes related to iron uptake, 7 genes related to magnesium ion uptake, and 46 genes related to the secretion system.

[0041] Prediction of Drug Resistance Genes: Comparative analysis of the drug resistance genes of strain dy58 Figure 10 It shows that 326 total drug resistance genes are enriched in dy58. The drug resistance genes are annotated to 10 different types of antibiotics. There are more genes recruited for tetracycline antibiotics, macrolide antibiotics, and fluoroquinolone antibiotics, with the number of genes being 113, 101, and 97 respectively. Strain dy58 has broad-spectrum environmental resistance and strong environmental adaptability, and may have broad-spectrum applicability.

[0042] Siderophore gene prediction: The whole genome sequence of strain dy58 was analyzed for secondary metabolite synthesis gene clusters on the antiSAMSH website, which was rich in siderophore synthesis gene clusters (NRP-metallophore). The core siderophore synthesis genes of strain dy58 were annotated. Figure 11 It was shown that strain dy58 was annotated with 5 core siderophore synthesis genes (2335, 2336, 2341, 2344, 2350).

[0043] According to the bacterial morphology, physiological and biochemical characteristics, and molecular detection results of strain dy58, this strain was identified as Pseudomonas ( Pseudomonas resinovorans ), and its 16S rDNA gene sequence was as shown in SEQ ID NO: 1.

[0044] 3. Strain preservation The plant growth-promoting rhizobacterium dy58, classified and named as Pseudomonas resinovorans ( Pseudomonas resinovorans ), has been preserved in the China General Microbiological Culture Collection Center, located at No. 3, Building 1, Beichen West Road, Chaoyang District, Beijing, Institute of Microbiology, Chinese Academy of Sciences. The preservation number is CGMCC No. 30150, and the preservation date is March 26, 2024.

[0045] Example 2 A hydroponic experiment was conducted to investigate the growth-promoting effect of the plant growth-promoting rhizobacterium dy58 on potato plants.

[0046] 1. Hydroponic experiment Test plants: Sterile tissue culture seedlings of potato ( Solanum tuberosum L.) cultivar Desiree (hereinafter referred to as DES for short). The tissue culture seedlings were propagated through axillary buds and grown in an artificial climate chamber using MS30 solid medium. The culture temperature was set at 20°C ± 1°C, humidity 60% ± 5%, light intensity 3000 - 4000 lx, and photoperiod 16 h light / 8 h dark. After 15 - 20 days of tissue culture seedling propagation, potato plants with normal growth and uniform growth vigor were selected for planting.

[0047] 1 / 2 Hoagland nutrient solution was used as the basal medium, and 50 mL centrifuge tubes with planting baskets were used as hydroponic colonization devices for planting; 35 ml of nutrient solution was added to each centrifuge tube, and 1 potato seedling with similar growth vigor was planted in each centrifuge tube. According to 20 replicates for each treatment, they were randomly grouped.

[0048] One week after hydroponics, the original plant height of the plants was measured with a vernier caliper, and after the hydroponic experiment ended, the top bud and young leaves of the potato plants were sampled to measure the chlorophyll content of the leaves.

[0049] The specific measurement method is as follows: Plant height: Use a ruler to measure the height from the top of each potato plant to the surface of the absorbent cotton in the planting basket. Measure in parallel and repeat, and calculate the mean value, which is the plant height of the potato plant. Calculate the Δ7 d growth rate according to the following formula: Δ7d growth rate = (plant height at 7 d - initial plant height) / initial plant height.

[0050] Chlorophyll content: After 21 d of inoculated hydroponics, sample the apical young leaves of the potato plants. Use a punching sampler with an 8 mm aperture to collect the young leaves of the plants. Add 1 mL of chlorophyll extraction solution (acetone: absolute ethanol: water = 4.5∶4.5∶1) to every two samples, and let it stand in the dark until the leaf tissue becomes transparent. Take the extract and measure the absorbance at wavelengths of 645 nm and 663 nm. Calculate the chlorophyll content according to the following formula: Total chlorophyll content (mg / gFW1) = (20.2×Abs645 nm + 8.02×Abs 663 nm)×V / (1000×W) V is the volume of the extraction solution used (mL); W is the leaf sampling area (dm 2 ) or the sampled fresh weight (g).

[0051] Bacterial liquid preparation: (1) After overnight culture and activation of the strain dy58, pick a single colony into LB medium and culture it at 30 °C with 200 rpm for 10 - 12 h as the seed inoculation solution. Transfer the seed solution to LB medium at 1% (volume ratio) and culture it overnight with shaking at 36 °C and 200 rpm.

[0052] (2) Centrifuge at 6000 rpm for 5 min to collect the bacterial cells. Resuspend and wash the bacterial cells 1 - 2 times with sterile 0.9% sodium chloride solution, and then resuspend the bacterial cells with sterile 0.9% sodium chloride solution to adjust the OD 600 to 1.0 as the bacterial liquid inoculation preparation.

[0053] Inoculate 1 mL of the bacterial liquid inoculation preparation into each tube of potato plants, and mix the bacterial liquid inoculation preparation with the liquid culture medium.

[0054] Table 1 shows the measurement results of the growth indexes of potato DES seedlings in the control group and the experimental group in the hydroponics experiment. According to the data in the table, it can be calculated that, compared with the control group, the 7 d plant height growth rate and the chlorophyll content per unit area of potato DES in the experimental group increased by approximately 148.04% and 123.53% respectively. Table 1 Growth status of potato DES seedlings in the hydroponics experiment

[0055] As Figure 12 andFigure 13 As shown, a comparison diagram of the experimental group and the control group of potato DES plants after inoculating the strain dy58 by hydroponics is presented. It can be seen from the figure that the growth rate of potato DES plants in the experimental group is faster, the plants are taller, and the leaves are greener. The above results indicate that inoculating the strain dy58 by hydroponics can significantly increase the plant height growth rate and chlorophyll content per unit area of potato DES plants.

[0056] Example 3 A pot experiment was conducted to investigate the growth-promoting effect of the plant growth-promoting rhizobacterium dy58 on potato plants.

[0057] Test plants: Potato ( Solanum tuberosum L.) common commercial cultivation variety Desiree potato tubers.

[0058] Treatment of potato tubers before cultivation: Select potato tubers with uniform size, healthy and without mechanical damage, soak the tubers in a gibberellin solution with a concentration of 10 mg / L for 1 h, take out the tubers, dry the surface, and store them in the dark and ventilated place until bud eyes and small buds appear, then they can be used for pot cultivation.

[0059] The germinated potato tubers were sown in hard plastic flower pots filled with 15 L of field soil from the potato planting base, and the tubers were buried 10 cm deep for cultivation. Two treatments, the control group (DES-CK) and the experimental group dy58 (DES-dy58), were set up, and 15 pots were designed in parallel for each treatment.

[0060] 1. Preparation of the bacterial suspension inoculation preparation: The method is the same as that in Example 2.

[0061] Application of the strain: The application amount of the bacterial suspension inoculation preparation is 10 mL per potato plant. When applying, the bacterial suspension inoculation preparation is diluted to 250 mL and poured into the roots of the potato plants. For the blank treatment, 10 mL of sterile 0.9% NaCl solution is diluted in the same proportion and applied to the roots of the plants.

[0062] Application period: The bacterial suspension inoculation preparation was applied 7 days after all the plants emerged from the soil. Each application was carried out every 14 days for a total of 3 consecutive applications. The application time was in the morning, evening or on cloudy days to avoid the failure of applying the bacterial suspension inoculation preparation due to direct sunlight at high temperature at noon.

[0063] 2. Determination of potato yield and quality.

[0064] Plant height: Use a ruler to measure the height of the plant from the ground to the top at the start of inoculation, and measure it once every 14 days. Calculate the Δ14 d growth rate according to the following formula: Δ14 d growth rate = (plant height at 14 d - initial plant height) / initial plant height Chlorophyll content: During the full bloom stage of the potato plants and the period of high nutrient demand when potatoes are forming, a hole puncher is used to take samples by punching holes in the young leaves at the top of the plants. The method for measuring chlorophyll content is the same as that in the hydroponic experiment.

[0065] Yield per plant: After the above-ground parts of the potato plants wither, the tubers are collected. All plants in each treatment are harvested individually, and the yield of each plant is measured using a one-percent balance.

[0066] Determination of mineral element content: Medium-sized tubers are randomly selected from each individual plant, peeled, and freeze-dried powder is prepared for the detection of mineral elements such as iron and zinc. A quantitatively weighed 0.3 g of the freeze-dried potato powder sample is placed in a polytetrafluoroethylene digestion tank, 7 mL of super-grade pure nitric acid and 2 mL of 30% hydrogen peroxide are added. After sealing the above sample, it is digested in a microwave digestion instrument according to the procedure in Table 3. After digestion, the digestion tube is opened and placed in an infrared acid expelling device for acid expelling (180 °C, 30 - 60 min) until the remaining sample is about 2 mL, then the acid expelling is ended. The sample is diluted to 25 mL and then prepared for on-machine detection of mineral element content. The content of the sample to be detected is measured using a flame atomic absorption spectrophotometer according to the instrument-set parameters; the standard curve method is adopted to determine the content of iron and zinc elements in the sample.

[0067] Table 3. Microwave digestion procedure

[0068] Table 3 shows the measurement results of the growth indexes of potato DES in the control group and the experimental group in the pot experiment. According to the data in the table, it can be calculated that, compared with the control group, the 14-day plant height growth rate, chlorophyll content per unit area, yield per plant, Fe and Zn contents in tubers of potato DES in the experimental group increased by approximately 66.34%, 18.67%, 36.67%, 30.83% and 171.24% respectively.

[0069] Table 3. Growth status of potato DES seedlings in the pot experiment.

[0070]

[0071] As Figure 14As shown in the figure, it is a comparison diagram of potato DES plants in the experimental group and the control group after inoculating the strain dy58 in the pot experiment. It can be seen from the figure that the potato plants in the control group showed phenomena such as yellowing of the top leaves and smaller plant size. By adding the strain dy58 externally, the yellowing of the top leaves of the plants was improved. The growth-promoting effect of the strain during the plant growth process was reflected from three indicators: plant height growth rate, chlorophyll content, and yield per plant. After the potatoes were harvested, relevant indicators such as the Fe content and Zn content of the potato tubers were measured to reflect the effect of exogenous inoculation with the strain dy58 on the nutritional quality of potatoes. The above results showed that inoculating the strain dy58 in the pot experiment could significantly increase the plant height growth rate, chlorophyll content per unit area, yield per plant, and the Fe and Zn contents of the potato tubers of potato DES plants.

[0072] Without conflict, the above-mentioned embodiments and the features in the embodiments in this article can be combined with each other.

[0073] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A plant growth-promoting rhizobacterium strain, characterized in that, The strain mentioned above is the plant growth-promoting rhizobacterium dy58, which was deposited on March 26, 2024 at the General Microbiological Center of the China National Center for Culture Collection of Microorganisms, and was taxonomically named Pseudomonas resinovorans. Pseudomonas resinovorans The deposit number is CGMCC No. 30150.

2. A bacterial agent, characterized in that, The microbial agent contains the plant growth-promoting rhizobacterium dy58 described in claim 1.

3. The microbial agent according to claim 2, characterized in that, The microbial agent is a microbial agent for promoting plant growth and / or a microbial agent for improving soil.

4. The bacterial agent according to claim 3, characterized in that, The improvement of the soil is manifested as the production of siderophores.

5. The microbial agent according to claim 3, characterized in that The promotion of plant growth is manifested as all or part of the following: increasing the plant height growth rate of plants, the chlorophyll content in plant leaves, the yield per plant, and / or the iron and zinc contents in plant fruits.

6. The microbial agent according to claim 5, characterized in that, The plant is potato.

7. Use of the plant growth-promoting rhizobacteria strain dy58 according to claim 1 or the microbial agent according to claim 2, characterized in that, It includes any of the following applications: A1) Application in improving soil; A2) Application in promoting plant growth; A3) Application in the production of siderophores; A4) Application in the production of products containing siderophores.

8. The application according to claim 7, wherein The promotion of plant growth is manifested as all or part of the following: increasing the plant height growth rate of plants, the chlorophyll content in plant leaves, the yield per plant, and / or the iron and zinc contents in plant fruits, and the plant is potato.

9. A method for promoting plant growth, characterized in that, It includes the following steps: applying the plant growth-promoting rhizobacterium dy58 described in claim 1 or the microbial agent described in claim 2 to plant plants, plant seeds, or the rhizosphere soil of plants.

10. A method for improving soil, characterized in that, It includes the following steps: applying the plant growth-promoting rhizobacterium dy58 described in claim 1 or the microbial agent described in claim 2 to the soil to be improved; the improvement of the soil is manifested as the production of siderophores.

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