Methylbacterium strain YM05 and application thereof in promoting plant growth and increasing plant yield

Abstract

The application discloses a methylobacterium YM05 and application of the methylobacterium YM05 in promoting plant growth and increasing plant yield. Methylorubrum The classification name of the methylobacterium YM05 is methylobacterium sp., and the preservation number is CGMCC No.32294; the colony of the methylobacterium YM05 is orange, round, upward protruding, with neat edges and a film-like surface. The methylobacterium YM05 has the abilities of efficiently synthesizing indole acetic acid IAA, ACC deaminase, iron carrier and nitrogen fixation, the bacteria and a bacterial agent prepared from the bacteria can significantly promote the seedling growth of corn and sorghum and increase the yield, and the effect is stable after being applied for many years and many points, so that the methylobacterium YM05 has important significance for protecting the farmland environment and developing green agriculture.

Description

Technical Field

[0001] This invention belongs to the fields of microbial technology and modern agricultural technology, specifically relating to a strain of Methylobacterium YM05 and its application in promoting plant growth and increasing plant yield. Background Technology

[0002] Microbial inoculants are green, sustainable, and environmentally friendly live bacterial preparations with increasingly widespread applications in agricultural production. Methylbacillus acts as a biostimulant, biopesticide, and biofertilizer; epiphytic / endophytic in the rhizosphere and foliage, it releases phytostimulants and mitogens, promoting root development and nutrient absorption, enhancing leaf photosynthetic efficiency, and promoting flowering / fruit retention / quality improvement; it also enhances plant immunity and releases various disease-resistant factors; and it fixes nitrogen, solubilizes phosphorus and potassium, and supplements root and foliar nutrition. Methylbacillus can be applied through seed treatment, drip irrigation, and foliar spraying, making it suitable for vast farmlands and facility agriculture; foliar spraying is suitable for special agricultural scenarios such as saline-alkali tidal flats. Methylbacillus uses methanol, a byproduct of plant growth, as a carbon source, without competing for nutrients needed for plant growth. While promoting crop growth, it also sequesters carbon dioxide and methanol, contributing to carbon sequestration and emission reduction. Some methylbacteria, such as endophytic nitrogen-fixing methylbacterium symbioticum, methylbacterium hispanicum, methylbacterium oryzea, methylbacterium radiotolerans, and methylbacterium gregans, have been reported to promote the growth of crops such as corn, sorghum, soybeans, and peanuts, and have been applied in agricultural production.

[0003] Corn is not only a major food crop but also an important feed and industrial raw material, serving as a crucial source for food processing, light industry, and pharmaceuticals. In my country, its planting area exceeds 600 million mu (approximately 40 million hectares), making it the largest food crop. my country is a major corn consumer and trader, ranking second globally in total consumption, and its corn imports account for over 10% of the global total, indicating a relatively high dependence on the international market. In 2019, the US corn yield was 10,532.3 kg / ha, while my country's corn production was only 6,317.1 kg / ha (FAO, 2020), indicating significant room for improvement. Sorghum is an important economic crop. In the past five years, my country's sorghum planting area has exceeded 7.5 million mu (approximately 433,000 hectares) per year, with a yield reaching 2.5 million tons per year. It has diverse uses, including food, sugar production, and medicinal applications, and is in high demand. Companies such as Newleaf and Corteva in the US have applied for patent protection for the application of Methylbacillus in promoting growth and disease resistance in crops such as corn, soybeans, potatoes, and sorghum. Currently, there are no domestically developed Methylbacillus agents and related products with completely independent intellectual property rights, and corresponding patent protection is also lacking. Therefore, there is an urgent need to develop Methylbacterium and its related products with completely independent intellectual property rights, which can effectively promote the growth of corn and sorghum, increase yield per unit area, and provide a green and environmentally friendly approach for modern agriculture. Summary of the Invention

[0004] The purpose of this invention is to provide a strain of *Methylobacterium* YM05 and its application in promoting plant growth and increasing plant yield. The *Methylobacterium* YM05 provided by this invention has the ability to efficiently synthesize indoleacetic acid (IAA), ACC deaminase, siderophores, and fix nitrogen from the air, effectively promoting the growth and increasing the yield of maize and sorghum.

[0005] To achieve the above-mentioned objectives, the present invention employs the following technical solution:

[0006] This invention provides a strain of Methylorubrum YM05, classified as Methylorubrum sp., with accession number CGMCC No. 32294.

[0007] Furthermore, the colonies of the Methylobacterium strain YM05 are orange-red, round, upward-protruding, with neat edges and a membrane-like surface.

[0008] The present invention also provides a methylbacterium inoculant containing the aforementioned methylbacterium strain YM05.

[0009] This invention also provides the application of Methylbacillus YM05 and / or Methylbacillus inoculants in promoting plant growth.

[0010] This invention also provides the application of Methylbacillus YM05 and / or Methylbacillus inoculants in improving plant yield.

[0011] Furthermore, the plants include corn and sorghum.

[0012] Furthermore, the corn includes regular corn, sweet corn, black corn, waxy corn, and high-oil corn.

[0013] Furthermore, the sorghum includes white sorghum, red sorghum, and yellow sorghum.

[0014] Furthermore, the application methods of the aforementioned Methylobacterium strain YM05 include seed dressing, drip irrigation, root irrigation, and foliar spraying.

[0015] Furthermore, the methylbacterium YM05 is capable of efficiently synthesizing indoleacetic acid, ACC deaminase, siderophores, and nitrogen gas that can fix air.

[0016] Furthermore, the methylbacterium inoculant is used to treat corn and sorghum seeds, and the methylbacterium strain YM05 contains no less than 10% bacteria. 9 CFU / mL.

[0017] Furthermore, the bacterial count should be no less than 10. 9 The dosage of CFU / mL methylbacterium inoculant is 5-25 mL per kilogram of seeds. The seed mixing temperature is 18-22℃, the mixing time is 5-10 min, and the drying time is 0.5-2 h.

[0018] Furthermore, the methylbacterium inoculant is sprayed during the seedling stage of corn and sorghum, wherein the methylbacterium inoculant contains no less than 10 bacteria. 9 The concentration of CFU / mL is 10-25 mL per acre for spraying.

[0019] Compared with existing technologies, this invention has the following advantages and beneficial effects: This invention screened a *Methylobacterium* strain YM05 from corn leaves, which possesses the ability to efficiently synthesize indoleacetic acid (IAA), ACC deaminase, siderophores, and nitrogen fixation. This strain and its prepared inoculum can significantly promote the seedling growth and yield increase of corn and sorghum, exhibiting high stability and good efficacy. For corn and sorghum grown in saline-alkali land, foliar spraying of the aforementioned *Methylobacterium* strain YM05 also significantly increased the yield of corn and sorghum. The application of the *Methylobacterium* strain YM05 described in this invention is of great significance for protecting the arable environment and promoting the development of green agriculture. Attached Figure Description

[0020] Figure 1 This is a colony morphology diagram of the methylbacterium YM05.

[0021] Figure 2 This is a graph showing the ACC deaminase production capacity of the Methylobacterium YM05.

[0022] Figure 3 This is a diagram showing the growth of the methylbacterium YM05 on a nitrogen-free plate.

[0023] Figure 4 This is a growth curve of the methylbacterium YM05 on a liquid nitrogen-free culture medium.

[0024] Figure 5 This is a comparison image of maize seedlings treated with the Methylobacterium YM05 inoculum and maize seedlings in the control group.

[0025] Figure 6 This is a comparison image of sorghum seedlings treated with the Methylobacterium YM05 inoculum and sorghum seedlings in the control group.

[0026] Figure 7 This is a comparison image of maize plants in the field treated with the Methylobacterium YM05 inoculum and maize plants in the control group.

[0027] Figure 8 This is a comparison image of corn cobs from the field treated with the Methylobacterium YM05 inoculum and the control group.

[0028] Figure 9 This is a comparison image of maize plants in the field treated with the Methylobacterium YM05 inoculum under nitrogen-reduced conditions and maize plants in the control group. Detailed Implementation

[0029] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0030] Example 1: Isolation and purification of strain YM05

[0031] The samples were obtained from the 11th robust leaf at the large trumpet stage of maize grown in the field in Aksu City, Aksu Prefecture, Xinjiang Uygur Autonomous Region. 1-2 g of the leaf from the middle of the 11th robust leaf was weighed and placed in a sterile shake flask, then 20-30 mL of modified R2A liquid medium was added. The flask was incubated on a shaker (30 ℃, 200 rpm) for 4-6 h for enrichment. After enrichment, serial dilutions were performed (10⁻⁶ ppm). -1 10 -2 10 -3 Spread 50-100 µL of the diluted solution onto modified R2A solid medium, invert it, and incubate at 30°C for 3-6 days. Pick pink single colonies onto modified HM solid medium with methanol as the sole carbon source and VB5 added, and continue incubating for 3-6 days. Pick pink single colonies with a diameter of 0.9-1.2 mm and repeat the purification process three times to obtain the pure culture YM05 strain. The colony morphology of YM05 strain on modified HM solid medium is as follows. Figure 1As shown, the colony is orange-red, round, upward-protruding, with neat edges and a membranous surface. The 16S rRNA sequence of strain YM05 was amplified and sequenced using primer pairs 27F (5'-AGAGTTTGATCCTGGCTCAG-3') and 1492R (5'-GGTTACCTTGTTACG ACTT-3'), and its 16S rRNA sequence is shown in SEQ ID NO.1. BLAST alignment confirmed that strain YM05 is *Methylorubrum* sp.

[0032] The modified R2A medium formula is as follows: 0.2-0.3g tryptone, 0.4-0.6g acid-hydrolyzed casein, 0.4-0.6g yeast extract, 0.4-0.6g soluble starch, 0.2-0.4g dipotassium hydrogen phosphate, 0.1-0.2g magnesium sulfate, 0.2-0.4g sodium pyruvate, 0.4-0.6g glucose, 10-15g agar, add water to 1 L, pH 7-7.4, and sterilize at high temperature.

[0033] The modified HM medium formula is as follows: 3-4 g dipotassium hydrogen phosphate trihydrate, 1-2 g sodium dihydrogen phosphate dihydrate, 0.1-0.3 g magnesium sulfate heptahydrate, 0.4-0.6 g ammonium sulfate, 5-15 mg disodium EDTA, 0.5-2 mg ferrous sulfate heptahydrate, 1-2 mg calcium chloride dihydrate, 0.5-2 mg manganese chloride tetrahydrate, 0.1-0.3 mg sodium molybdate dihydrate, 0.2-0.4 mg copper sulfate pentahydrate, 1-2 mg cobalt chloride hexahydrate, 3-5 mg zinc sulfate heptahydrate, and 20-30 g agar. Add water to 1 L, sterilize at high temperature, and then add 3-10 mL of methanol filtered through a 0.22 μm filter membrane.

[0034] The YM05 strain was deposited at the China General Microbiological Culture Collection Center (CGMCC), located at No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing, Institute of Microbiology, Chinese Academy of Sciences, on October 21, 2024. The accession number for Methylorubrum sp. YM05 is CGMCC No. 32294.

[0035] Example 2: Physiological and biochemical function tests of strain YM05

[0036] This embodiment tests the ability of YM05 strain to synthesize indoleacetic acid (IAA), 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase, siderophores, and nitrogen fixation.

[0037] 1. Test of IAA production capacity of Methylobacterium

[0038] Activate the *Methylobacterium* strain YM05 on solid modified HM medium. Pick a single colony and place it into a test tube containing 2–3 mL of liquid modified HM medium. After culturing for 2–3 days, transfer the YM05 culture that has reached the exponential phase to a 250 mL shake flask and incubate with 40–50 mL of modified HM medium (containing 50–100 μg / mL L-tryptophan). Set up three biological replicates to ensure consistent initial OD. After 5–7 days of incubation, centrifuge 1–2 mL of the culture at 12000 g for 5–10 min. Mix the supernatant with an equal volume of Salkowski's reagent (1 mL of 0.5 M FeCl3·6H2O added to 50 mL of 35% (v / v) H2SO4). Incubate at room temperature in the dark for 20–30 min. Measure the OD of the reaction solution at 530 nm and calculate the IAA yield based on the standard curve. Preparation of standard curve: Prepare IAA standard solutions with concentrations of 80, 40, 20, 10, 5, 2.5, 1.25, 1, 0.5, 0.25, and 0.1 μg / mL. React these solutions with Salkowski's reagent according to the method described above, and then measure the OD. 530 A standard curve was plotted. The reaction solution turned pink, indicating that strain YM05 can produce IAA.

[0039] The modified HM medium formula is as follows: 3-4 g dipotassium hydrogen phosphate trihydrate, 1-2 g sodium dihydrogen phosphate dihydrate, 0.1-0.3 g magnesium sulfate heptahydrate, 0.4-0.6 g ammonium sulfate, 5-15 mg disodium EDTA, 0.5-2 mg ferrous sulfate heptahydrate, 1-2 mg calcium chloride dihydrate, 0.5-2 mg manganese chloride tetrahydrate, 0.1-0.3 mg sodium molybdate dihydrate, 0.2-0.4 mg copper sulfate pentahydrate, 1-2 mg cobalt chloride hexahydrate, 3-5 mg zinc sulfate heptahydrate, and 20-30 g agar. Add water to 1 L, sterilize at high temperature, and then add 3-10 mL of methanol filtered through a 0.22 μm filter membrane.

[0040] 2. Identification of the ACC deaminase production capacity of Methylobacterium YM05

[0041] Single colonies of activated Methylobacterium YM05 were picked and placed on nitrogen-deficient HM medium (without ammonium sulfate). The culture dish was divided in two; the right side was treated with 2-3 mM ACC as the sole nitrogen source and spread evenly, while the left side remained untreated. The dishes were incubated at 30 °C for 3-6 days. Single colonies were observed growing on the right side. Figure 2 As shown, this indicates that strain YM05 can utilize ACC as a nitrogen source, that is, it can produce ACC deaminase.

[0042] The formula for nitrogen-deficient HM medium is as follows: 3-4 g dipotassium hydrogen phosphate trihydrate, 1-2 g sodium dihydrogen phosphate dihydrate, 0.1-0.3 g magnesium sulfate heptahydrate, 5-15 mg disodium ethylenediaminetetraacetate, 0.5-2 mg ferrous sulfate heptahydrate, 1-2 mg calcium chloride dihydrate, 0.5-2 mg manganese chloride tetrahydrate, 0.1-0.3 mg sodium molybdate dihydrate, 0.2-0.4 mg copper sulfate pentahydrate, 1-2 mg cobalt chloride hexahydrate, 3-5 mg zinc sulfate heptahydrate, and 20-30 g agar. Add water to 1 L, sterilize at high temperature, and then add 3-10 mL of methanol filtered through a 0.22 μm filter membrane.

[0043] 3. Siderophore production capacity test of Methylobacterium YM05

[0044] Single colonies of *Methylobacterium* YM05 were picked and cultured in modified HM liquid medium at 200 rpm and 30 °C for 2-3 days. The YM05 culture in test tubes that had reached the exponential phase was then transferred to 250 mL shake flasks and cultured in modified HM medium. Three biological replicates were set up to ensure consistent initial OD. After 3-5 days of culture, 0.5-1 mL of the culture was centrifuged at 10000 g for 5-10 min. The supernatant was mixed with an equal volume of CAS detection reagent and reacted in the dark at room temperature for 25-30 min. The OD (As) of the reaction solution was measured at 630 nm. Separately, an equal volume of blank medium was mixed with the CAS detection solution, and its absorbance was used as a reference (Ar). The relative content of siderophores was calculated using the formula [(Ar-As) / Ar]×100%. A bluish-gray color in the reaction solution indicates that strain YM05 can produce siderophores.

[0045] CAS detection reagent preparation method: Reagent 1: Dissolve 50-60 mg of chromazone in 50 mL of ultrapure water; Reagent 2: Dissolve FeCl3·6H2O in 10 mM hydrochloric acid to prepare a 1-2 mM FeCl3·6H2O solution; Reagent 3: Dissolve 60-75 mg of HDTMA in 40 mL of ultrapure water. After mixing Reagent 1 and Reagent 2 thoroughly, slowly add Reagent 3 while stirring to obtain the CAS detection solution (20×). Dilute before use.

[0046] 4. Nitrogen fixation capacity test of Methylbacillus

[0047] A single colony of the *Methylobacterium* strain YM05 was picked and inoculated onto modified DMSZ Medium No. 3 nitrogen-free medium and incubated at 30 °C for 5-8 days. Colony growth was observed. Figure 3 As shown, the colonies are pink, round, raised upwards, with neat edges and a membrane-like surface, indicating that strain YM05 has nitrogen-fixing ability.

[0048] Single colonies of the *Methylobacterium* strain YM05 were picked and cultured in modified HM liquid medium at 200 rpm and 30 °C for 2-3 days. The YM05 culture in test tubes that had reached the exponential phase was transferred to 500 mL shake flasks and cultured in modified DMSZ Medium No. 3 nitrogen-free medium. Three biological replicates were set up to ensure consistent initial OD values. The OD of the reaction solution was measured at 630 nm, and growth curves were plotted. It was found that strain YM05 could also grow on liquid medium. Figure 4 As shown, this indicates that strain YM05 has nitrogen-fixing ability.

[0049] A single colony of *Methylobacterium* YM05 was picked and cultured in modified HM liquid medium at 200 rpm and 30 °C for 2-3 days. The YM05 bacterial culture in test tubes that had reached the exponential phase was transferred to a 500 mL shake flask and cultured for 3-5 days until the mid-to-late exponential phase. The bacterial culture was collected and centrifuged at 10000 g for 5-10 min. The bacterial pellet was resuspended in 10-20 mL of modified DMSZ Medium No. 3 nitrogen-free medium and transferred to a 300 mL dropper bottle. 5-10% acetylene gas was injected using a syringe, mixed thoroughly, and the bottle was incubated at 30 °C and 220 rpm on a shaker for 2-4 h. 0.1-0.25 mL of gas was extracted from the bottle, and the formation of acetylene in the gas was detected by gas chromatography (GC). The GC analysis revealed an ethylene peak, indicating that strain YM05 can reduce acetylene to ethylene and possesses nitrogenase activity.

[0050] The formulation of DMSZ Medium No.3 is as follows: glucose 3-7 g, mannitol 3-7 g, calcium chloride dihydrate 0.1-0.2 g, magnesium sulfate heptahydrate 0.1-0.2 g, sodium molybdate dihydrate 3-7 mg, dipotassium hydrogen phosphate 0.7-1.2 g, potassium dihydrogen phosphate 0.1-0.2 g, ferrous sulfate heptahydrate 0.01-0.02 g, calcium carbonate 3-7 g, agar 15-20 g, and 1 L of water. Simultaneously, add 1 mL of a trace element solution per 40 mL of medium. The trace element solution consists of zinc sulfate heptahydrate 7-12 mg, manganese chloride tetrahydrate 2-5 mg, boric acid 20-40 mg, cobalt chloride hexahydrate 15-30 mg, copper chloride dihydrate 0.5-1.5 mg, and nickel chloride hexahydrate 1-3 mg.

[0051] As shown in Table 1, strain YM05 possesses the ability to synthesize indoleacetic acid (IAA), 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase, siderophores, and nitrogen fixation.

[0052] Table 1: Identification of physiological and biochemical properties of Methylobacterium YM05

[0053]

[0054] Example 3: Methylobacterium YM05 promotes the growth of maize and sorghum seedlings

[0055] Pick a single colony of YM05 and place it into a test tube containing 2-3 mL of liquid HM medium. Incubate at 30 °C and 200 rpm for 2-3 days. Transfer 0.5-1 mL of the bacterial culture to 40-50 mL of liquid HM medium and incubate at 30 °C and 200 rpm for 3-4 days until OD (Organic Degradation). 600 The concentration is 2.0~2.5. Take 5~10 mL of bacterial culture, centrifuge at 6000 rpm for 5~10 min, discard the supernatant, add 5~10 mL of 10 mM MgSO4 solution, mix in a vortex mixer, centrifuge again at 6000 rpm for 5~10 min, discard the supernatant, add 5~10 mL of 10 mM MgSO4 solution, mix in a vortex mixer to obtain Methylobacterium YM05 bacterial agent (approximately 10). 9 (CFU / mL). Different application methods of Methylobacterium YM05 significantly promoted the growth of maize and sorghum seedlings.

[0056] Seed dressing: Dress 100-200 corn seeds and sorghum seeds separately with 5-10 mL of diluted Methylbacillus YM05. The amount of Methylbacillus YM05 per seed is 10 mL. 5 ~10 6 After thoroughly mixing CFU, sow the seeds into seedling trays filled with seedling substrate, making 32 seedling holes per group. Continue growing until day 30-35, then harvest the seedlings and measure their height, fresh weight, dry weight, and root dry weight. The results are shown in Table 2. Seedlings on day 35... Figure 5 and Figure 6 As shown.

[0057] Foliar spraying: Sow corn and sorghum seeds separately into seedling trays filled with seedling substrate, 32 seedling holes per group. 7-10 days after sowing, spray the corn and sorghum seedlings with a bacterial solution at a rate of 10... 5 ~10 6 CFU / plant. Continue growing until 30-35 days later, harvest the seedlings and measure the height, fresh weight, dry weight of the plant, and dry weight of the roots. The indicators are shown in Table 2.

[0058] Seed dressing + foliar spraying: Treat 100-200 corn seeds and sorghum seeds separately with 5-10 mL of diluted Methylbacillus YM05. The amount of Methylbacillus YM05 per seed is 10 mL. 5 ~10 6After thoroughly mixing CFU, sow the mixture into seedling trays filled with seedling substrate, making 32 seedling holes per group. 7-10 days after sowing, foliar spray the corn and sorghum seedlings with the bacterial solution, applying 10g of the solution. 5 ~10 6 CFU / plant. Continue growing until 30-35 days later, harvest the seedlings and measure the height, fresh weight, dry weight of the plant, and dry weight of the roots. The indicators are shown in Table 2.

[0059] Root irrigation: Sow corn and sorghum seeds separately into seedling trays filled with seedling substrate, with 32 seedling holes per group. On the 7th to 10th day after sowing, irrigate the corn and sorghum seedlings with a 10% root irrigation solution. 5 ~10 6 CFU / plant. Continue growing until 30-35 days later, harvest the seedlings and measure the height, fresh weight, dry weight of the plant, and dry weight of the roots. The indicators are shown in Table 2.

[0060] As shown in Table 2, different application methods of inoculating with the YM05 inoculant can significantly improve the growth of maize and sorghum seedlings. Compared with the control group, the plant height, fresh weight, plant dry weight, and root dry weight of maize seedlings inoculated with the YM05 inoculant were increased by 10-20%, 20-40%, 20-30%, and 10-20%, respectively. Compared with the control group, the height, fresh weight, root dry weight, and plant dry weight of sorghum seedlings inoculated with the YM05 inoculant were increased by 15-25%, 15-35%, 20-35%, and 10-25%, respectively.

[0061] Table 2: Growth-promoting effects of different application methods of Methylobacterium YM05 inoculant on corn and sorghum seedlings

[0062]

[0063] Example 4: Methylbacillus YM05 inoculant promotes the growth of maize and sorghum plants in the field.

[0064] In the field experiment, each experimental group had 6 × 20 m 2 Machine sowing was used, with a row spacing of 70 cm and a plant spacing of 25 cm, resulting in 8 rows per group. After 20-30 days and 50-60 days of growth in the field, the experimental groups were sprayed with Methylbacillus YM05 inoculant at a concentration of 10... 5 ~ 10 6 CFU / plant, spraying rate 2-3 L / group; control group sprayed with 10 mM magnesium sulfate solution, spraying rate 2-3 L / group; 5 points were sampled during the grain-filling stage, 10 healthy plants were continuously collected from each point, for a total of 50 plants, to statistically analyze the growth of maize and sorghum plants in the field. Results are shown in Table 3 and... Figure 7As shown, treatment with Methylbacillus YM05 inoculant increased maize plant height by 10-15% and ear leaf length by 12-15%; treatment with Methylbacillus YM05 inoculant increased sorghum plant height by 15-20%. Methylbacillus YM05 inoculant had no significant effect on stem diameter of either maize or sorghum plants.

[0065] Table 3: Methylobacterium YM05 inoculum promotes the growth of corn and sorghum plants

[0066]

[0067] Example 5: Methylbacillus YM05 inoculant increases yield of field corn and sorghum.

[0068] The method described in Example 4 was used to plant maize and sorghum in different areas to investigate the effect of YM05 inoculant on the yield of maize and sorghum. Maize was planted in multiple locations over several years (2023 Pingdu summer maize, 2024 Jimo spring maize, and 2024 Pingdu summer maize). Maize and sorghum were harvested separately after maturity, and ear length, thousand-grain weight, and yield per mu were recorded. The results are shown in Table 4 and... Figure 8 As shown, treatment with Methylbacillus YM05 inoculant increased corn ear length by 5-10%, thousand-grain weight by 8-12%, and yield per mu by 14-18% compared to the control group, with stable results observed in multi-year, multi-location tests. In Dongying's saline-alkali land, application of Methylbacillus YM05 to corn increased ear length by 5-8%, thousand-grain weight by 8-10%, and yield per mu by 8-10%. Treatment with Methylbacillus YM05 inoculant also increased sorghum ear length by 12-16%, thousand-grain weight by 10-15%, and yield per mu by 15-20% compared to the control group. In Dongying's saline-alkali land, application of Methylbacillus YM05 to sorghum increased sorghum ear length by 9-11%, thousand-grain weight by 8-10%, and yield per mu by 7-10%.

[0069] Table 4: Methylobacterium YM05 inoculum increases corn and sorghum yields

[0070]

[0071] Example 6: Methylbacillus YM05 inoculant increases the yield of maize and sorghum in saline-alkali soil fields.

[0072] The method described in Example 4 was used to plant maize and sorghum in saline-alkali land in Guangrao County, Dongying City, to test the effects of YM05 inoculant on the yield of maize and sorghum in saline-alkali land. The results are shown in Table 4. For maize planted in saline-alkali land, the application of Methylbacillus YM05 increased ear length by 5-8%, thousand-grain weight by 8-10%, and yield per mu by 8-10% compared to the control group. For sorghum planted in saline-alkali land, the application of Methylbacillus YM05 increased ear length by 9-11%, thousand-grain weight by 8-10%, and yield per mu by 7-10% compared to the control group.

[0073] Example 7

[0074] Corn was planted in square pots measuring 16 cm × 45 cm, with 8-10 kg of field soil. Based on the nitrogen, phosphorus, and potassium requirements (1:0.48:0.8) throughout the corn growth cycle, different nitrogen-reduced basal fertilizers (N-0, N-10, N-25, N-50) were prepared. The nitrogen fertilizer was applied twice: half as basal fertilizer at sowing and half as top dressing during the corn's tasseling stage. The experimental group was treated with Methylobacterium YM05 seed dressing for 5-10 min (10... 5 ~10 6 CFU / grain), dry and sow, then manage normally after sowing, watering every 3-5 days with 1L of water. Apply fertilizer around the corn's small tassel stage, adding the remaining half of the nitrogen fertilizer. The experimental group also sprayed the leaves with the strain (10 CFU / grain). 5 ~10 6 CFU / plant). Sampling and evaluation are conducted approximately 50-60 days after corn emergence. For example... Figure 9 As shown, even with a nitrogen reduction of 10-25%, the fresh weight of corn plants still increased by 5-8% compared to the control group, the dry weight of plants increased by 4-6%, the nitrogen content of plant leaves increased by 6-9%, and the chlorophyll content of plant leaves increased by 4-7%.

[0075] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions claimed by the present invention.

Claims

1. A strain of Methylobacterium YM05, characterized in that, The classification name of the methylobacterium YM05 is methylobacterium sp. Methylorubrum The classification name of the methylobacterium YM05 is methylobacterium sp. The colony of the methylobacterium YM05 is orange, round, upward protruding, with neat edges and a surface of a film shape. The methylobacterium YM05 is prepared by repeatedly purifying three times a pink single colony with a diameter of 0.9-1.2 mm on a modified HM solid culture medium with methanol as a sole carbon source and VB5 added, and then continuing to culture for 3-6 days.

2. A methylobacterium inoculant characterized in that, The methylorubrum agent contains the methylorubrum YM05 of claim 1.

3. Use of the methylbacterium YM05 according to claim 1 and / or the methylbacterium agent according to claim 2 for promoting plant growth, characterized in that, The application mode of the methylorubrum YM05 and the methylorubrum agent includes seed dressing, drip irrigation, root irrigation and foliar spraying, the methylorubrum YM05 can efficiently synthesize indole acetic acid, ACC deaminase, siderophore and can fix nitrogen in the air, and the plants include corn and sorghum.

4. Use of the Methylobacterium YM05 of claim 1 or the Methylobacterium inoculant of claim 2 for increasing plant yield, characterized in that, The application mode of the methylorubrum YM05 and the methylorubrum agent includes seed dressing, drip irrigation, root irrigation and foliar spraying, the methylorubrum YM05 can efficiently synthesize indole acetic acid, ACC deaminase, siderophore and can fix nitrogen in the air, and the plants include corn and sorghum.

5. Use according to claim 3 or 4, characterized in that, The methyl bacillus strain YM05 is used for seed dressing of corn and sorghum, and the bacterial content is not less than 10 9 CFU / mL; the methyl bacillus agent with bacterial content not less than 10 9 CFU / mL is used in an amount of 5-25 mL per kilogram of seeds, the seed dressing is carried out at a temperature of 18-22 ℃, the seed dressing is carried out for 5-10 min, and the seed is dried for 0.5-2 h.

6. Use according to claim 3 or 4, characterized in that, Spraying the methylobacterium agent on the seedling stage of corn and sorghum, the bacteria content in the methylobacterium agent is not less than 10 9 CFU / mL, the spraying amount is 10-25 mL per mu.

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