Endophytic penicillium oxalicum with salt-resistant, growth-promoting, drought-resistant and insect-resistant functions, microbial agent and application of endophytic penicillium oxalicum

Abstract

The invention relates to the field of microorganisms, in particular to endophytic penicillium oxalicum with salt-resistant, growth-promoting, drought-resistant and insect-resistant functions, a microbial agent and application of the endophytic penicillium oxalicum. The invention provides Penicillium oxalicum, and the preservation number of the Penicillium oxalicum is CGMCC (China General Microbiological Culture Collection Center) No. 42249. Aiming at the industrial pain point of function fragmentation of the existing microbial preparation, a natural single strain integrating four functions of salt resistance, drought resistance, growth promotion and insect killing is obtained through screening; the limitation that in the prior art, the functions of a stress-resistant strain (the salt-resistant growth-promoting function of the kasuna HH-2), a growth-promoting strain (the drought-resistant growth-promoting function of the bacillus cereus F06) and an insecticidal strain are separated is broken through, and the problems that the cost is high and the compatibility is poor when multiple preparations are combined are solved.

Description

Technical Field

[0001] This invention relates to the field of microorganisms, and more particularly to a plant endophytic Penicillium oxalate with salt tolerance, growth promotion, drought resistance and insect resistance functions, microbial inoculants and their applications. Background Technology

[0002] Agricultural production is facing the dual challenges of global climate change and ecological degradation, with soil salinization, drought stress, and pest infestation being the three core issues restricting crop yields. According to the Food and Agriculture Organization of the United Nations, the global area of ​​saline-alkali land exceeds 1 billion hectares, and arid and semi-arid regions account for 41% of the land area. Lepidopteran pests (such as corn borers and cotton bollworms) can cause yield losses of 15% to 30% to major crops. Against this backdrop, microbial technology, due to its environmental friendliness, has become a key breakthrough for sustainable agricultural development, with related known technologies mainly focusing on three areas:

[0003] 1. Antimicrobial technology

[0004] To combat adverse conditions such as salinity and drought, researchers have isolated various salt- and drought-tolerant bacterial strains. For example, Bacillus pumilus developed by Qingdao Weilan Biotechnology Group can promote crop growth and alleviate the effects of salt damage in high-salt environments; Bacillus subtilis B21 significantly improves the survival rate and yield of cucumbers in saline-alkali land by regulating crop physiological metabolism. These strains mainly achieve stress resistance by secreting osmotic regulators (such as proline) and improving the root microenvironment, but generally lack growth-promoting or insecticidal functions.

[0005] 2. Plant growth-promoting microbial technology

[0006] Growth-promoting bacterial strains enhance crop yield through mechanisms such as nitrogen fixation, phosphorus solubilization, and auxin secretion. For example, Bacillus (Adj 1) and Priestia aryabhattai (Adj 6), isolated from agave, can secrete indoleacetic acid (up to 10.00 µg·mL). 1 The discovery of nitrogen-fixing bacteria and dissolved zinc significantly increased wheat yield under salt stress. Gansu Agricultural University's synergistic technology of rhizobia and Erwinia increased alfalfa fresh weight by 3.8 times through nitrogen fixation and extracellular polysaccharide secretion. However, the activity of these strains is easily inhibited under adverse conditions, and they lack pest control capabilities.

[0007] 3. Microbial insecticide technology

[0008] Bacillus thuringiensis (Bt) is currently the most widely used insecticidal microorganism, and its Cry toxin can specifically kill target pests. For example, Bt has a good control effect on underground pests, and Bacillus subtilis strains can produce metabolites that kill nematodes and insects, and are used to control corn rootworms. However, existing insecticidal strains are mostly targeted at single pest groups, and their insecticidal activity decreases significantly in saline-alkali and arid environments.

[0009] While the aforementioned technologies are mature in their individual functions, they all have limitations: the dispersed functions require multiple applications of different formulations in the field, increasing costs and easily causing antagonistic effects between strains, making it impossible to cope with the complex stresses of agricultural production. Summary of the Invention

[0010] In view of this, the present invention provides a plant endophytic Penicillium oxalate microbial agent with salt tolerance, growth promotion, drought resistance and insect resistance functions, and its application. Addressing the industry pain point of fragmented functions in existing microbial preparations, this invention obtains a single strain that naturally integrates four functions: salt tolerance, drought resistance, growth promotion and insecticidal properties. This overcomes the limitations of existing technologies where stress-resistant strains (Kushnerella HH-2 with salt tolerance and growth promotion function), growth-promoting strains (Bacillus cereus F06 with drought resistance and growth promotion function), and insecticidal strains have separate functions, solving the problems of high cost and poor compatibility when using multiple preparations in combination.

[0011] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0012] This invention provides Penicillium oxalicum, with accession number CGMCCNo.42249.

[0013] The present invention also provides microbial inoculants, comprising any one of the following and acceptable adjuvants:

[0014] (a) the aforementioned *Penicillium oxalicum*; and / or

[0015] (b) Inactivated Penicillium oxalicum; and / or

[0016] (c) Metabolites, derivatives, fermentation broths, cultures, exosomes, lysates, or extracts of the aforementioned Penicillium oxalicum.

[0017] The present invention also provides the application of the above-mentioned Penicillium oxalicum and / or the above-mentioned microbial agents in promoting plant growth and / or increasing yield.

[0018] The present invention also provides the application of the above-mentioned Penicillium oxalicum and / or the above-mentioned microbial agents in improving the salt tolerance of plants and / or alleviating salt stress in plants.

[0019] The present invention also provides the application of the above-mentioned Penicillium oxalicum and / or the above-mentioned microbial agents in improving plant drought resistance and / or alleviating plant drought stress.

[0020] The present invention also provides the application of the above-mentioned Penicillium oxalicum and / or the above-mentioned microbial agents in the prevention and / or killing of lepidopteran pests.

[0021] In some embodiments of the present invention, the lepidopteran pests mentioned above include one or more of the following: diamondback moth, beet armyworm, cotton bollworm, and armyworm.

[0022] In some embodiments of the present invention, in the above applications, the application concentration of the Penicillium oxalicum and / or the microbial agent is 10. 2 CFUs / L ~10 4 CFUs / L.

[0023] The present invention also provides a method for preventing and / or killing lepidopteran pests by applying the above-mentioned Penicillium oxalicum and / or the above-mentioned microbial agents to plants.

[0024] In some embodiments of the present invention, the concentration of the substance applied in the above method is 10. 2 CFUs / L ~10 4 CFUs / L.

[0025] The beneficial effects of this invention include:

[0026] (1) In response to the industry pain point of fragmented functions of existing microbial preparations, this invention obtains a single strain that integrates four functions of salt tolerance, drought resistance, growth promotion and insecticidal by screening. This breaks through the limitations of the existing technology where stress-resistant strains (Kushnerella HH-2 salt tolerance and growth promotion function), growth-promoting strains (Bacillus cereus F06 drought resistance and growth promotion function) and insecticidal strains have separate functions, and solves the problems of high cost and poor compatibility of multi-preparation combination.

[0027] (2) The *Penicillium oxalate* strain provided by this invention originates from the endophytic environment of plant leaves and has a natural affinity and co-evolutionary basis with plants. This endophytic characteristic enables it to colonize efficiently within plants, effectively avoiding fierce competition for microbial niches in the rhizosphere and phyllosphere, thereby establishing a stable and high-density dominant population. Compared with traditional soil-derived microbial agents, the strain of this invention solves the common industry problems of difficult colonization and unstable effects of exogenous strains, ensuring that its insect-resistant, growth-promoting, and drought-resistant functions can be sustained and stable throughout the entire growth period of the plant. This strain has multiple effects, originates from naturally healthy plants, and is applied back to plants. It is environmentally friendly, has high colonization efficiency within plants, and provides an efficient and reliable microbial solution for reducing dependence on chemical pesticides and fertilizers.

[0028] (3) In terms of single function dimension, each characteristic has achieved technological breakthroughs: In terms of salt tolerance, the strain can survive at a concentration of 15% NaCl and the colony growth is not significantly negatively affected, far exceeding the defect of the survival rate of ordinary insecticidal strains at a concentration of 1.5% salt; In terms of drought resistance, it has a positive effect on significantly improving the survival rate of plants after 7 consecutive days of drought stress; In terms of growth promotion function, it can significantly improve the seed emergence rate and the aboveground and underground biomass of crops; In terms of insecticidal function, it targets the young larvae of beet armyworm (corrected mortality rate ≥75.0%) and young larvae of cotton bollworm (corrected mortality rate ≥25.0%) that are common in cruciferous vegetables and corn fields. Through the dual pathway of "intestinal intake and intestinal wall penetration", the feeding intensity is significantly reduced within 24 hours in the poisoning experiment, and the mortality rate is over 50% within 48 hours. It is also safer for non-target organisms (mortality rate is less than 5%).

[0029] (4) The synergistic effect of the four functions forms a unique technical advantage: the salt and drought resistance characteristics provide a basic guarantee for the colonization of the strain in extreme environments, avoiding the problem of the activity decay of ordinary insecticidal strains in adversity; the growth promotion function enhances crop resistance and nutrient absorption, forming a virtuous cycle of "crop strengthening - pest control" with the insecticidal effect; while the insecticidal function reduces the extra loss of crops under adversity. The synergistic function of the strain itself is more suitable for complex scenarios such as saline-alkali land and arid areas, realizing the application value of "one agent with multiple effects", breaking the cost barrier and compatibility limitation of traditional technology that requires the use of three types of formulations.

[0030] (5) Long shelf life and low storage requirements. General live bacterial agents require low-temperature storage and have a short shelf life. A spore suspension stored at 4˚C in a 30% glycerol solution showed a spore germination rate of approximately 83.06% after two years. Spore powder stored at 4˚C showed a spore germination rate of approximately 90.39% after two years. Spore powder stored at room temperature for 8 months maintained a spore germination rate of approximately 89.87%. The requirements for long-term storage conditions and methods are extremely low. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below.

[0032] Figure 1 The electrophoresis results of PCR amplification products and the comparison results with the GenBank database are shown. Figure 1 The single band on the far right of the image above is the sample to be tested (indicated by the red arrow). There are no obvious extraneous bands, and the band is clear and bright. From left to right in the image, the amplification results are: 2000bp Marker of the sample, other Penicillium species, different species of the same genus as the strain of this invention, sample S (the sample to be tested in this invention), and 2000bp Marker. Figure 1 The image below shows the BLAST alignment results of the search sequences in NCBI GenBank;

[0033] Figure 2 The effects of bacterial strain treatment on the growth and development of pea plants are shown; where: A represents plant height (cm); B represents plant root length (cm); C represents plant fresh weight (g); and D represents root fresh weight (g).

[0034] Figure 3 The effect of bacterial solution treatment on plant emergence rate;

[0035] Figure 4 Comparison of plant survival rates after treatment with bacterial solution and subsequent drought stress;

[0036] Figure 5 The effects of bacterial strains and bacterial concentrations on the mortality rate of lepidopteran larvae are shown in Figures A-D, where A represents the beet armyworm, B the cotton bollworm, C the diamondback moth, and D the armyworm, respectively; the Y-axis represents the mean mortality rate of larvae (± standard error). NX1 and NX10 represent individual larvae fed a concentration of 10⁻¹⁰ mL. 4 CFUs / L and 10 2 CFUs / L of bacterial suspension;

[0037] Figure 6 The effects of bacterial strains and bacterial concentrations on the survival of young lepidopteran larvae (median survival time) are shown in Figures A-D, where: A represents the beet armyworm; B the cotton bollworm; C the diamondback moth; and D represents the average mortality rate of armyworm larvae (legend: mean larval mortality rate ± standard error). NX1 and NX10 represent individual feeds at a concentration of 10⁻¹⁰ per mL. 4 CFUs / L and 10 2 CFUs / L of bacterial suspension;

[0038] Among them: the control group was a negative control, without the addition of bacterial strains or bacterial solutions;

[0039] Figure 7 The image shows a pure culture of Penicillium oxalate strain on PDA solid medium; where: A shows the front of the colony; B shows the back of the colony.

[0040] Biological Preservation Instructions

[0041] Biological material: NX22; Classification and nomenclature: Penicillium oxalicum; Deposited on October 17, 2025 at the China General Microbiological Culture Collection Center (CGMCC); Address: Institute of Microbiology, Chinese Academy of Sciences, No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing; Accession number: CGMCC No. 42249. Detailed Implementation

[0042] This invention discloses a plant endophytic Penicillium oxalate with salt tolerance, growth promotion, drought resistance and insect resistance functions, microbial inoculants and their applications.

[0043] It should be understood that the expression “one or more of…” individually includes each of the objects described after the expression, as well as various different combinations of two or more of the described objects, unless otherwise understood from the context and usage. The expression “and / or” combined with three or more described objects should be understood to have the same meaning, unless otherwise understood from the context.

[0044] The terms “including,” “having,” or “containing,” including the use of their grammatical synonyms, should generally be understood as open-ended and non-restrictive, for example, not excluding other unstated elements or steps, unless otherwise specifically stated or understood from the context.

[0045] It should be understood that the order of the steps or the order in which certain actions are performed is not important as long as the invention remains operational. Furthermore, two or more steps or actions can be performed simultaneously.

[0046] The use of any and all instances or exemplary language such as “e.g.” or “including” in this document is merely intended to better illustrate the invention and is not intended to limit the scope of the invention unless the claims are made. No language in this specification should be construed as indicating that any unclaimed element is essential to the practice of the invention.

[0047] Furthermore, the numerical ranges and parameters used to define the present invention are approximate values, and the relevant values ​​in the specific embodiments have been presented as precisely as possible. However, any value inevitably contains standard deviations due to individual test methods. Therefore, unless explicitly stated otherwise, it should be understood that all ranges, quantities, values, and percentages used in this disclosure are modified with the word "approximately". Here, "approximately" generally means that the actual value is within plus or minus 10%, 5%, 1%, or 0.5% of a specific value or range.

[0048] In Examples 1 to 4 of this invention, all raw materials and reagents used can be purchased from the market.

[0049] The present invention will be further illustrated below with reference to the embodiments:

[0050] Example 1 Isolation and Identification of Strains

[0051] like Figure 1 As shown, healthy plant leaf samples without obvious damage were collected from alfalfa fields in the northern irrigation area of ​​Yinchuan, placed in sterile bags, and brought back to the laboratory. After rinsing the leaf samples under running water to remove surface debris, the samples were immersed in 70% alcohol for 2 minutes, then in 1% sodium hypochlorite solution for 2 minutes. In a laminar flow hood, the samples were transferred to sterile water and rinsed 3-5 times. Under sterile conditions, the leaves were cut into 0.5cm × 0.5cm pieces, transferred to PDA solid medium, and incubated at a constant temperature for 3-5 days. Typical single colonies of different morphologies were then picked, purified, and stored on slant at 4℃.

[0052] Pure cultures of the strain were collected, and fungal DNA was extracted using a fungal genomic DNA extraction kit. The ITS region was amplified by PCR using primers: ITS5: 5'-GGAAGTAAAAGTCGTAACAAGG-3' (as shown in SEQ ID NO:2) and ITS4: 5'-TCCTCCGCTTATTGATATGC-3' (as shown in SEQ ID NO:3). The 20 μL PCR reaction mixture consisted of 10 μL 2×TaqMaster Mix, 1 μL upstream primer, 1 μL downstream primer, 1 μL template DNA, and ddH2O added to a final volume of 20 μL. PCR conditions were as follows: 95℃ for 5 min; 95℃ for 30 s, 56℃ for 30 s, 72℃ for 1 min, 30 cycles; 72℃ for 5 min, then incubated at 4℃. The amplified products were subjected to agarose gel electrophoresis.

[0053] Sequence results:

[0054] Penicillium oxalicum NX22: (as shown in SEQ ID NO:1)

[0055] Example 2: Strain culture and inoculum preparation

[0056] Cultivation was performed in the laboratory using PDA plates, without special cultivation conditions. Mature spores were collected using Tween-20 aqueous solution to prepare a spore suspension. A 10... 5 The spore suspension at CFUs / mL should be stored at 4°C for later use. Before inoculating plants in the laboratory, dilute proportionally as needed.

[0057] Example 3 Biological Function Determination

[0058] (1) Screening of salt-tolerant strains

[0059] The strains were screened using selective medium containing 15% NaCl (v:v) PDA, and they grew normally.

[0060] (2) Screening of salt-tolerant growth-promoting strains

[0061] Use 1 mL of 10 5 Pea seeds were inoculated with a spore suspension at a concentration of CFUs / L to complete the plant growth experiment. Plants were cultured in an artificial climate chamber (25±3℃, photoperiod 16 L:8 D), watered every two days. Plant growth data, including plant height (cm), root length (cm), plant fresh weight (g), root fresh weight (g), germination rate, and plant survival rate under stress, were collected 14 days after germination. (See Table 1 and...) Figures 2-4 (As shown).

[0062] Table 1

[0063]

[0064] Table 1 shows that after 10 5 After inoculating seeds with a spore suspension at a concentration of CFUs / L, plant growth information was collected 14 days after germination, including data recording and statistical analysis of plant height (cm), root length (cm), plant fresh weight (g), root fresh weight (g), and germination rate (P<0.05).

[0065] like Figure 2 As shown, after 10 5 After inoculating seeds with a spore suspension at a concentration of CFUs / L, plant growth information was collected 14 days after germination, including statistical analysis results of plant height (A), root length (B), plant fresh weight (C), and root fresh weight (D). * The results indicated a significant difference between the treatment group and the control group (P<0.05). The bacterial solution treatment showed a certain promoting effect on the aboveground and underground growth and development of the plants, and significantly increased the fresh weight of the plant roots (P<0.0001).

[0066] Figure 3 It is stated that after 10 5 After inoculating seeds with a spore suspension at a concentration of CFUs / L, the germination rate was calculated 14 days after germination. The control group used a spore-free solution. The germination rate of the control group was 72.22%, while that of the treatment group was 86.11%.

[0067] (3) Screening of drought-resistant strains

[0068] The same seed treatment was applied, followed by drought stress 14 days after emergence. Watering was stopped for 7 days and then resumed. The plant survival rate (%) was then recorded.

[0069] Figure 4 It is stated that after 10 5Seeds were inoculated with a spore suspension at a concentration of CFUs / L. Drought stress was applied 14 days after emergence, followed by a 7-day watering halt, followed by rewatering. Plant survival rates (%) were then recorded. The control group received a spore-free solution. The survival rate of the control group was 8.33%, while the survival rate of the treatment group was 72.22% (Table 1).

[0070] (4) Screening out some functional strains with dual resistance to salt and insects.

[0071] Two bacterial suspension concentration gradients were set up to screen the insecticidal resistance of bacterial strains against seven lepidopteran insects, including the diamondback moth (Plutella xylostella), beet armyworm (Spodoptera exigua), cotton bollworm (Helicoverpa armigera), armyworm (Mythimna separata), fall armyworm (Spodoptera frugiperda), corn borer (Ostrinia furnacalis), and beet armyworm (Spodoptera litura). Among these, the insecticidal resistance of the strains against the three major lepidopteran agricultural pests—fall armyworm, corn borer, and beet armyworm—was not ideal.

[0072] In an experiment on the mortality rate of second-instar larvae of four lepidopteran pests (diamond moth, beet armyworm, cotton bollworm, and armyworm) under different concentrations of bacterial agents, the insecticidal effect of the bacterial strains showed significant differences in mortality efficiency under different concentration gradient treatments. Figure 5 (Table 2). Furthermore, survival curves of young lepidopteran larvae from four species (diamond moth, beet armyworm, cotton bollworm, and armyworm) were plotted under different feeding dosages to help evaluate the effect of feeding dosage on the adaptability of lepidopteran larvae. Figure 6 ).

[0073] Table 2. Statistical analysis results of mortality rate (%) of young Lepidoptera larvae in different treatment groups.

[0074]

[0075] Figure 5 This study statistically analyzed the mortality rates (%) of different bacterial agent concentrations against the young larvae of four lepidopteran pests: beet armyworm (A), cotton bollworm (B), diamondback moth (C), and armyworm (D). NX1 represents high concentration, and NX10 represents low concentration. Table 2 shows the statistical analysis results of lepidopteran larval mortality rates in different treatment groups.

[0076] Figure 6 It can be seen that under different feeding dosage treatments, the survival curves and individual risk tables of four species of lepidopteran larvae, namely beet armyworm (A), cotton bollworm (B), diamondback moth (C), and armyworm (D), were obtained.

[0077] in, Figure 6 Figure A shows the survival curves of the beet armyworm, displaying three survival curves. The survival rate of the control group (CK) remained relatively stable, indicating the highest survival rate. The survival rate of the NX1 group decreased the fastest, indicating the lowest survival rate in this group. The survival rate of the NX10 group decreased the second fastest, indicating a moderate survival rate. The three curves are clearly separated, indicating a significant difference in survival rates among the groups (P < 0.0001). The NX1 group had the lowest survival rate (the curve drops sharply), while the NX10 group was in the middle. The risk table shows that the number of at-risk individuals in each group gradually decreased over time: no deaths were observed in the CK group; the time points from 60 to 0 individuals in both the NX1 and NX10 groups were 2→4→6→8→10; the NX1 group experienced the fastest event. The NX1 group was the high-risk group, with a rapidly declining survival rate.

[0078] Figure 6 B represents the survival curve of the cotton bollworm. The survival probability of the CK control group remained close to 1.0, indicating that almost no deaths occurred in this group; the survival probability of the NX10 group decreased gradually, suggesting a low-risk characteristic; the survival probability of the NX1 group was flat in the early stage and then dropped sharply in the later stage, indicating a significantly increased risk in the later stage. The figure indicates a highly significant difference in survival rates among the three groups (P < 0.0001). The risk table shows that the sample size of the CK group remained at 60 (no deaths), the sample size of the NX1 group decreased rapidly over time (e.g., from 60 to 41), and the decrease in the NX10 group was slower (e.g., from 60 to 45). The CK group had the highest survival rate and no deaths, representing a low-risk control group; the NX1 group had the lowest survival rate, especially with a significantly increased mortality rate in the later stage. The risk table data is consistent with the survival curve, further confirming that the NX1 group had the highest cumulative rate of events.

[0079] Figure 6 C represents the survival curve of the diamondback moth. The CK group (control group) consistently had the highest survival probability (close to 1.0), indicating that this group had the best survival rate. The survival probability of the NX1 group decreased the fastest, while the NX10 group was in the middle. The Log-rank test result showed P = 0.00057, indicating that the difference in survival rates among the three groups was extremely significant. The NX1 group had the lowest survival rate (the curve dropped sharply), and the sample size decreased rapidly. The risk table shows that over time, the sample size of the NX1 group decreased rapidly, the NX10 group decreased slowly, and the CK group remained stable. There were extremely significant differences in survival rates among the different treatment groups (p < 0.001). The CK group (control group) had the highest and most stable survival rate, the NX1 group had the fastest decline in survival rate and the strongest treatment, resulting in the lowest survival rate, while the NX10 group was in between.

[0080] Figure 6Figure D represents the survival curves of the armyworm, showing three survival curves. The CK group consistently had the highest survival probability, the NX1 group (yellow) experienced the fastest decline in survival probability, and the NX10 group (blue) fell in between. The CK group had the highest and most stable survival rate, with no deaths; the NX1 group's survival rate declined rapidly, with deaths concentrated in the early stages, resulting in the worst prognosis; the NX10 group's survival rate was between the two, but the number of individuals at risk reached zero in the later stages, leading to all-cause mortality. The figure shows P = 0.00028, which is much less than 0.05, indicating that the difference in survival rates among the three groups is statistically significant. The risk table data shows that over time, the number of individuals in the NX1 group decreased from 60 to 45 (time point 10), showing the fastest decline; the number of individuals in the NX10 group decreased from 60 to 0 (time point 10), showing a significant decline in the middle stage; the CK group maintained 60 individuals throughout the process, with no deaths. The changes in the number of individuals at risk further support the differences in the survival curves among the groups.

[0081] Example 4: Spore activity assay

[0082] (1) Preservation and determination of glycerol solution

[0083] Take 1 mL of 10 10 A spore suspension of CFU / mL was thoroughly mixed with 19 mL of 30% glycerol solution in a sterile centrifuge tube. The samples were sealed and stored at 4°C. Samples were collected and analyzed after 0 months (initial), 6 months, 12 months, and 24 months of storage. For each sample collection, 0.1 mL of the storage solution was serially diluted with 10% Tween 20 aqueous solution to the appropriate concentration. 0.1 mL of the diluted solution was then spread onto plate counting agar and incubated at 37°C for 24 hours. The spore germination rate was then calculated. The formula for calculating the spore germination rate is:

[0084]

[0085] (2) Determination of spore powder preservation

[0086] Transfer the dried spore powder into sterile centrifuge tubes, seal them, and store them in a refrigerator at 4°C. Samples were taken at 0 months (initial), 6 months, 12 months, and 24 months after storage, with each sample being approximately 0.01 g. The samples were serially diluted with 10% Tween 20 aqueous solution to an appropriate concentration. 0.1 mL of the diluted solution was spread onto plate counting agar medium and incubated at 37°C for 24 h. The spore germination rate was then counted.

[0087] (3) Preservation test of spore powder at room temperature

[0088] Transfer 0.5g of dried spore powder into a sterile centrifuge tube, seal it, and store it in a dark environment at room temperature (20-25℃). Take samples after 8 months of storage, and use the same sampling and germination rate detection methods as above.

[0089] Table 3. Statistical analysis results of spore germination rate (%) under 4℃ storage environment.

[0090]

[0091] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. Penicillium oxalicum, characterized by, Its accession number is: CGMCC No.42249.

2. A microbial inoculant, characterized in that, Includes any of the following and acceptable adjuvants: (a) *Penicillium oxalicum* as described in claim 1; and / or (b) Inactivated Penicillium oxalicum as described in claim 1; and / or (c) Metabolites, derivatives, fermentation broths, cultures, exosomes, lysates, or extracts of Penicillium oxalicum as described in claim 1.

3. The application of Penicillium oxalicum as described in claim 1 and / or the microbial inoculant as described in claim 2 in promoting plant growth and / or increasing yield.

4. The application of Penicillium oxalicum as described in claim 1 and / or the microbial agent as described in claim 2 in improving plant salt tolerance and / or alleviating plant salt stress.

5. The application of Penicillium oxalicum as described in claim 1 and / or the microbial inoculant as described in claim 2 in improving plant drought resistance and / or alleviating plant drought stress.

6. The application of Penicillium oxalicum as described in claim 1 and / or the microbial agent as described in claim 2 in the prevention and / or killing of lepidopteran pests.

7. The application as described in claim 6, characterized in that, The lepidopteran pests include one or more of the following: diamondback moth, beet armyworm, cotton bollworm, and armyworm.

8. The application as described in claim 6 or 7, characterized in that, The application concentration of the Penicillium oxalicum and / or the microbial agent is 10. 2 CFUs / L ~10 4 CFUs / L.

9. A method for controlling and / or killing lepidopteran pests, characterized in that, Apply the Penicillium oxalicum as described in claim 1 and / or the microbial agent as described in claim 2 to the plant.

10. The method as described in claim 9, characterized in that, The applied concentration is 10. 2 CFUs / L ~10 4 CFUs / L.

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