Endophytic fungus pr38 and application thereof

Abstract

This invention discloses an endophytic fungus Pr38 and its applications, belonging to the field of microbial technology. The endophytic fungus Pr38 is classified and named... Pezicula sp. Pr-38, deposited at the China Center for Type Culture Collection (CCTCC) under accession number CCTCC NO: M 20252460, has been shown to promote the growth of tomato seedlings and enhance the tolerance of rice plants, especially seedlings, to cadmium when co-cultured with tomatoes and rice. Therefore, the endophytic fungus Pr38 has significant potential for widespread application in protecting plant health and improving the tolerance of rice seedlings to cadmium.

Description

Technical Field

[0001] This invention relates to the field of microbial technology, specifically to an endophytic fungus. Pezicula sp.Pr-38 and its application in promoting tomato growth and improving rice's tolerance to cadmium. Background Technology

[0002] Plant endophytic fungi, as a natural biological resource, refer to fungi that live inside the tissues or organs of healthy plants at certain or all stages of their life cycle, but whose host plants do not exhibit external disease symptoms. Numerous studies have shown that endophytic fungi can improve nutrient utilization efficiency through nitrogen fixation, phosphorus solubilization, and potassium solubilization; directly stimulate plant growth by synthesizing plant growth hormones (such as IAA and GA); effectively control pests and diseases by activating systemic resistance in plants or directly producing active substances such as antibiotics and alkaloids; and significantly enhance plant resistance to drought, salinity, heavy metals, and extreme temperatures through mechanisms such as regulating osmotic pressure and enhancing antioxidant enzyme activity.

[0003] In recent years, research on the application of endophytic fungi in agriculture has increased, especially in promoting plant growth and improving plant resistance. For example, a novel endophytic fungus, *Durum oryzae*, was isolated from the root tissue of healthy wild rice. Harpophora oryzae It can significantly promote rice growth and biomass accumulation (Yuan, ZL, et al A new species of Harpophora (Magnaporthaceae) recovered from healthy wild rice( Oryza granulata ) roots, representing a novel member of a beneficial darkseptate endophyte. FEMS Microbiol. Lett. 2010:307,94-101.). Endophytic fungi of *Pyriformis indicus* ( Piriformospora indica It can significantly improve plant growth, development, and stress resistance through enhancing plant antioxidant capacity, regulating hormone signaling, maintaining osmotic pressure balance, slowing down photosynthetic pigment degradation, and regulating gene expression (Zhuo Guangwen et al. Research progress on the interaction between Indian piriformis and plants. Natural Science, 2025, 13(4): 723-731.). Dark-colored septate endophytic fungal species Acrocalymma vagum Inoculation at the roots of tobacco plants can significantly reduce the content of heavy metals in tobacco leaves (Hui-Qing Jin, et al. Effect of the dark septate endophytic fungus Acrocalymmavagum on heavy metal content in tobacco leaves. Symbiosis , 2018, 74:89-95.).

[0004] Therefore, by utilizing the role of endophytic fungi in promoting plant growth and enhancing plant stress resistance, endophytic fungi can be developed into a new generation of microbial fertilizers, biopesticides, and plant stress inducers, which can be widely applied to crops such as grains, vegetables, and fruit trees. This represents a transformation in agriculture from "chemical confrontation" to "biological synergy," and has profound theoretical value and practical significance for promoting green agricultural development and ensuring food security. Summary of the Invention

[0005] The purpose of this invention is to provide a novel endophytic fungal strain that promotes crop growth and enhances crop resistance through symbiotic interaction with crop plants.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] This invention isolated a strain belonging to the genus *Platycodon* from the root system of *Phragmites australis*. Pezicula A novel strain (sp.) was identified, with the following main biological characteristics: colony diameter of 6 cm after 7 days of growth on PDA plates at 25°C; underdeveloped aerial hyphae, creeping along the culture medium surface, white colonies, and transparent or white hyphae; and absence of conidia. The ITS sequence of this endophytic fungus is shown in SEQ ID NO.1. Phylogenetic tree construction confirmed that this strain belongs to the kingdom Fungi. Fungi Ascomycota Ascomycota Truffles Leotiomycetes ,Fluoromycetes Helotiales Pyromycetes Dermateaceae genus *Platycota* Pezicula Therefore, it is named: Pezicula sp. Pr-38 was deposited on November 6, 2025 at the China Center for Type Culture Collection (CCTCC), Wuhan University, Wuhan, China, with accession number CCTCC NO: M 20252460.

[0008] Furthermore, the culture conditions for the endophytic fungus strain Pr38 were as follows: the endophytic fungus Pr38 was inoculated into PDA solid medium and cultured in the dark at 22-25℃ for 7-10 days.

[0009] This invention provides a formulation of endophytic fungus Pr38, which is prepared into a liquid microbial fertilizer. The preparation method of the liquid microbial fertilizer includes: inoculating the endophytic fungus Pr38 into a liquid fermentation medium, culturing until the medium is filled with mycelia, and obtaining the liquid microbial fertilizer. The liquid fermentation medium is composed of 5 g potato starch, 10 g peptone, and 15 g glucose per 1000 mL.

[0010] This invention also provides another formulation of the endophytic fungus Pr38, which is prepared into a solid microbial fertilizer. The preparation method of the solid microbial fertilizer includes: inoculating the endophytic fungus Pr38 into a liquid fermentation medium to obtain a fermentation broth, then inoculating the fermentation broth onto sterile barley grains, mixing the fermentation broth and sterile barley grains at a ratio of 150 mL: 200 g, and culturing in the dark at 25°C until the mycelium grows and covers the barley grains, thereby obtaining Pr38 solid microbial fertilizer; the composition of the liquid fermentation medium is: 5 g potato extract powder, 10 g peptone, and 15 g glucose per 1000 mL.

[0011] The application method of the liquid or solid microbial fertilizer can be as follows: the liquid or solid microbial fertilizer is mixed into the seedling substrate, and the germinated crop seeds are sown in the seedling substrate containing endophytic fungus Pr38. During the seedling process, endophytic fungus Pr38 colonizes the roots of the seedlings.

[0012] This invention has found that colonizing the endophytic fungus Pr38 into the root tissue of tomatoes significantly promotes the growth of tomato seedlings. The interaction between the endophytic fungus Pr38 and tomato seedlings can significantly enhance the growth performance of tomato seedlings.

[0013] Therefore, this invention provides the application of the endophytic fungus Pr38 in promoting tomato growth. The application includes co-culturing the endophytic fungus Pr38 with tomato plants.

[0014] Furthermore, the application includes: co-culturing tomato seeds with the endophytic fungus Pr38 after germination, allowing them to colonize the roots of tomato seedlings to promote seedling growth.

[0015] Co-culturing the Pr38 strain with tomato plants in the form of microbial fertilizer can significantly promote the growth of tomato seedlings.

[0016] Furthermore, the indicators for tomato growth include plant height, fresh weight, leaf width, and stem width.

[0017] This invention has found that... Peziculasp. Pr-38, when colonized in the root tissues of rice, significantly promoted the growth of rice seedlings in cadmium-contaminated soil and enhanced their tolerance to cadmium. Under cadmium stress, the interaction between the endophytic fungus Pr38 and rice seedlings significantly improved the growth performance of rice seedlings. Indicators of rice growth included plant fresh weight and plant height.

[0018] Therefore, the present invention provides the application of the endophytic fungus Pr38 in improving the tolerance of rice to cadmium stress, the application comprising: co-culturing the endophytic fungus Pr38 with rice plants.

[0019] Furthermore, the application includes: co-culturing rice seeds with the endophytic fungus Pr38 after germination, allowing it to colonize the roots of rice seedlings, thereby improving the tolerance of rice seedlings to cadmium stress.

[0020] By co-cultivating rice seedlings with strain Pr38 in the form of microbial fertilizer, and allowing it to colonize the roots of rice seedlings, the growth of rice seedlings under cadmium stress conditions can be significantly promoted.

[0021] Furthermore, the application includes: preparing endophytic fungus Pr38 into solid microbial fertilizer, mixing it into a seedling substrate to obtain a mixed substrate, and sowing rice seeds in the mixed substrate after germination to obtain rice seedlings.

[0022] Furthermore, the co-culture conditions are: 22-25℃, 16 h light / 8 h dark culture.

[0023] The beneficial effects of this invention are as follows:

[0024] This invention provides a novel endophytic fungus, Pr38, which, when interacting with tomato, significantly promotes tomato growth under normal conditions; and when interacting with rice, significantly promotes rice growth under cadmium stress. Co-culturing Pr38 with tomato and rice, respectively, and allowing it to colonize the root tissues of both, promotes tomato plant growth and enhances the cadmium tolerance of rice plants, especially seedlings. The endophytic fungus Pr38 has significant potential for widespread application in ensuring plant health and improving the cadmium tolerance of rice seedlings. Attached Figure Description

[0025] Figure 1 Phylogenetic tree of strain Pr38.

[0026] Figure 2 This is a test of the cadmium tolerance of strain Pr38 on a plate in Example 2.

[0027] Figure 3 This shows the colonization of strain Pr38 on rice roots.

[0028] Figure 4This section describes the effect of strain Pr38 on tomato seedlings in Example 4. A-B represent the effect of strain Pr38 on the growth of potted tomato seedlings; C represents the effect of strain Pr38 on the growth of a single potted tomato seedling; D-G represent the effect of strain Pr38 on growth indicators of potted tomato seedlings, corresponding to plant height, single-plant fresh weight, leaf width, and stem width, respectively. The bar chart represents the mean ± standard deviation, n=9. Significant differences were determined using Tukey's method with one-way ANOVA for multiple comparisons, where CK represents the control and Pr38 represents the inoculated strain Pr38.

[0029] Figure 5 This section describes the effect of strain Pr38 on cadmium tolerance in potted rice seedlings in Example 5. A represents the effect of strain Pr38 on the growth of potted rice seedlings under cadmium tolerance conditions; B represents the effect of strain Pr38 on the growth of individual potted rice seedlings under cadmium stress; C-D represent the effects of strain Pr38 on seedling growth indicators under cadmium stress, corresponding to plant height and fresh weight, respectively. The bar chart represents the mean ± standard deviation, n=9. Significant differences were determined using Tukey's method with multiple comparisons, where CK represents the control and Pr38 represents the inoculated strain Pr38. Detailed Implementation

[0030] The present invention will be further described below with reference to specific embodiments. These embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Any modifications or substitutions made to the methods, steps, or conditions of the present invention without departing from the spirit and essence of the invention are within the scope of the invention.

[0031] Unless otherwise specified, the experimental methods used in the following examples are conventional methods; the materials and reagents used are commercially available unless otherwise specified.

[0032] Example 1: Isolation, purification and identification of endophytic fungus strain Pr38

[0033] I. Strains Isolation and Purification

[0034] Strain Pr38 was isolated from the root system of the wild plant *Arundo donax*. The specific method was as follows: the wild plant roots were continuously rinsed with tap water to carefully remove soil particles and appendages. Healthy root tissue was selected and surface disinfected. First, it was disinfected with 1% sodium hypochlorite for 20 min, then rinsed four times with sterile deionized water. The root tissue was then cut into 0.5 cm segments and placed in 2% malt extract agar (MEA, malt extract agar, OXOID; 50 mg / L chloramphenicol was added to inhibit the growth of endophytic bacteria) and incubated in the dark at 25°C. Hyphae were observed every 24 h. Endophytic fungal hyphae growing from the edges of the tissue cuts were carefully picked out with a toothpick, transferred to fresh PDA medium for purification, and the strain was recorded as Pr38.

[0035] PDA medium: Each liter contains 20 g glucose, 200 g potato, and 15 g agar. Weigh the required amount of potato according to the volume of the medium to be prepared, boil it in water, mash and dissolve it, filter it, add glucose and agar, and autoclave at 121°C for 20 min.

[0036] II. Strain Identification

[0037] 1. Morphological identification

[0038] After isolation and purification, strain Pr38 was inoculated onto PDA medium and cultured at 25°C for 7 days. A small amount of bacterial cells was picked up with a needle, prepared onto a glass slide, and observed and measured under a microscope.

[0039] Its morphological characteristics are as follows: strain Pr38 grows rapidly on PDA plates, and the colony diameter is 6 cm after 7 days of growth at 25℃; aerial hyphae are underdeveloped, creeping on the surface of the culture medium, the colonies are white, and the hyphae are transparent or white.

[0040] 2. Molecular identification

[0041] (1) DNA extraction

[0042] ① After culturing Pr38 strain on PDA plates at 25℃ for 7 days, scrape the mycelium from the plates with a toothpick and place it into a sterilized centrifuge tube containing 300 μL of extraction buffer (1 M KCl, 100 mM Tris HCl, 10 mM EDTA, pH=8.0);

[0043] ② Grind with an electric grinder and shake vigorously for 2 minutes;

[0044] ③ Centrifuge at 10000 rpm for 10 min;

[0045] ④ Aspirate the supernatant and transfer it to another new centrifuge tube, discarding the precipitate;

[0046] ⑤ Add an equal volume of isopropanol (analytical grade) to the supernatant, gently invert and mix several times, then centrifuge at 12000 rpm for 10 min to precipitate nucleic acids;

[0047] ⑥ Gently pour off the supernatant and invert the centrifuge tube containing the precipitate onto absorbent paper to drain the water;

[0048] ⑦ Add 300 μL of 70% ethanol, gently invert and mix several times, then centrifuge at 12000 rpm for 2 min;

[0049] ⑧ Gently pour off the supernatant and repeat step ⑦ once;

[0050] ⑨ Invert the centrifuge tubes onto absorbent paper to drain excess water, and place them at 37°C for 15 minutes to allow the ethanol to evaporate completely;

[0051] ⑩ The precipitate was resuspended in 50 μL ddH2O to obtain Pr38 genomic DNA at a concentration of 30 ng / μL.

[0052] (2) PCR amplification of fungal ITS rDNA gene

[0053] PCR amplification was performed in a 50 μL reaction system containing: 2 μM each of forward and reverse primers, 200 μM dNTPs, 1.5 mM MgCl2, 5 μL 10×PCR buffer, 2 μL template DNA, and 2 U Taq enzyme.

[0054] The upstream primer ITS1 sequence is: 5'-TCCGTAGGTGAACCTGCGG-3'.

[0055] The downstream primer ITS4 sequence is: 5'-TCCTCCGCTTATTGATATGC-3'.

[0056] PCR amplification was performed on a Lange MG96G PCR instrument. Reaction conditions: 94℃ pre-denaturation for 2 min, followed by 35 cycles of: 94℃ denaturation for 30 sec, 55℃ annealing for 40 sec, 72℃ extension for 1 min, and a final extension at 72℃ for 10 min.

[0057] (3) Recovery and purification of PCR products

[0058] After the PCR reaction was completed, the PCR products were detected by 1% agarose gel electrophoresis and then purified using the DNA gel purification kit from Aspirin Biotechnology Co., Ltd., following the instructions in the kit's manual.

[0059] (4) Gene sequencing and sequence analysis

[0060] The purified and recovered target DNA fragment, after electrophoresis detection, was sent to the Hangzhou sequencing department of Youkang Biotechnology Co., Ltd. for sequencing. After rigorous verification, the sequencing results yielded a DNA fragment sequence of 558 bp, as shown in SEQ ID NO.1.

[0061] On the NCBI website, the determined nucleotide sequence was searched and compared with homologous or similar nucleotide sequences in the GenBank database using BLAST. After BLAST alignment, the sequence showed 99% coverage and 98.73% similarity to accession number MN121298.1. This sequence originates from the genus *Platycota*. Pezicula The ITS rDNA sequence of sp. strain CBS 110609.

[0062] Phylogenetic tree ( Figure 1 The results showed that Pr38 is associated with the genus *Pseudococcus* (…). Crptosporiopsis The phylogenetic relationship between and is greater than that between and genus *Platycota* (…). Pezicula Pr38 is closer to the genus *Pseudomonas*. The support at the nodes within the genus *Pseudomonas* is relatively low, therefore it is not appropriate to directly classify it as a member of the genus *Pseudomonas*. Based on the combined results of the nucleotide sequence and phylogenetic tree, Pr38 is considered to be a member of the genus *Pseudomonas*. Pezicula () new strains that have not yet been identified.

[0063] The above molecular and morphological identification results indicate that this strain belongs to the kingdom Fungi. Fungi Ascomycota Ascomycota Truffles Leotiomycetes ,Fluoromycetes Helotiales Pyromycetes Dermateaceae genus *Platycota* Pezicula Therefore, it is named: Pezicula sp. Pr-38 was deposited at the China Center for Type Culture Collection (CCTCC), Wuhan University, Wuhan, China, on November 6, 2025, with accession number CCTCC NO: M 20252460. The collection was identified as viable on November 13, 2025.

[0064] Example 2: Tolerance of endophytic fungus Pr38 to cadmium stress

[0065] 1. Activation culture of bacterial strains

[0066] The Pr38 strain preserved on the slant was inoculated onto potato dextrose agar (PDA) solid medium for activation culture, and cultured in the dark at 25°C for 7 days for later use.

[0067] PDA medium: Each liter contains 20 g glucose, 200 g potato, and 15 g agar. Weigh the required amount of potato according to the volume of the medium to be prepared, boil it in water, mash and dissolve it, filter it, add glucose and agar, and autoclave at 121°C for 20 min.

[0068] 2. Testing the tolerance of strain Pr38 to cadmium concentration gradients.

[0069] The concentrations of cadmium ions (cadmium elemental solution standard, China Weiye Measurement) in PDA medium were 0 mg / L, 2 mg / L, and 4 mg / L. Strain Pr38 was inoculated onto PDA medium with different cadmium concentration gradients and cultured at 25°C in the dark for 7 days.

[0070] 3. Results Analysis

[0071] like Figure 2 As shown, different Cd 2+ Concentration causes differences in Pr38 colony morphology. Under no cadmium stress conditions, colonies are white. As the cadmium concentration increases, the colony diameter gradually decreases. When the cadmium concentration is 2 mg / L, the colony diameter decreases, but the color hardly changes. When the cadmium concentration is 4 mg / L, the colony diameter is even smaller, and the overall color becomes whiter.

[0072] Example 3: Colonization of endophytic fungus Pr38 in rice roots

[0073] 1. Activation culture of bacterial strains

[0074] The Pr38 strain preserved on the slant was inoculated onto potato dextrose agar (PDA) solid medium for activation culture, and cultured in the dark at 25°C for 7 days for later use.

[0075] 2. Co-culture of Pr38 strain with rice

[0076] After removing the husks from rice seeds, shriveled, dry, and insect-infested grains were removed. Healthy rice seeds were disinfected with 75% alcohol for 5 minutes, followed by 1% NaClO for 20 minutes. The seeds were then rinsed five times with sterile water before use. The disinfected seeds were transferred to half MS medium using sterile forceps, sealed with sealing film, and incubated at 25°C for germination (16 h light / 8 h dark). After 3-4 days, the emerging seeds were inoculated into square dishes containing half MS + PDB medium, with 8-9 seeds per dish. For the treatment group, 6-7 Pr38 mycelial discs (5 mm in diameter) were inoculated under the seeds; for the control group, sterile mycelial discs were inoculated into half MS + PDB medium. Each treatment was repeated in triplicate, incubated at 25°C under 16 h light / 8 h dark for 15-20 days until the three-leaf stage.

[0077] 1 / 2 MS+PDB medium: per 1000 mL contains 0.5 g MES, 2.2 g MS Salt, 5 g sucrose, 8 g agar powder, 17.5 g PDB, pH 5.7, autoclaved at 121℃ for 20 min.

[0078] 3. Trypan blue staining of rice roots

[0079] The rice roots of the control group and the treatment group were cleaned, dried, and cut into 1 cm sections. The rice roots were stained with trypan blue and then observed under an inverted fluorescence microscope.

[0080] 4. Results Analysis

[0081] Colonization status such as Figure 3 As shown in Figures A and B, the control group had a small amount of uniform blue dye residue in the intercellular spaces or tissue edges, but it did not penetrate into the root cells; the treated rice root cells had clearly visible hyphal structures, indicating that Pr38 hyphae could invade the root cells.

[0082] Example 4: Endophytic fungus Pr38 promotes tomato growth

[0083] 1. Activation culture of bacterial strains

[0084] The Pr38 strain preserved on the slant was inoculated onto potato dextrose agar (PDA) solid medium for activation culture, and cultured in the dark at 25°C for 7 days for later use.

[0085] 2. Preparation of Pr38 liquid microbial fertilizer

[0086] Endophytic fungal mycelial blocks (0.5 cm in diameter) of Pr38, cultured for 7 days, were placed in PDB liquid fermentation medium (containing 5 g potato extract, 10 g peptone, and 15 g glucose per 1000 mL) for fermentation (25℃, 150 rpm, 7 days). Pr38 liquid microbial fertilizer was obtained when the PDB liquid fermentation medium was fully covered with mycelium.

[0087] 3. Co-culture of strain Pr38 with tomato

[0088] (1) Application of liquid microbial fertilizer: Mix the fermented liquid microbial fertilizer with the seedling substrate and use it as new substrate soil for tomato potted plants. Soak the tomato seeds and place them in a 37℃ dark constant temperature incubator to germinate for 2 days. When the seeds show white sprouts, sow them evenly in the seedling tray.

[0089] (2) Pot cultivation of tomato seedlings: Tomato seeds were cultivated in seedling trays for 30 days (22-25℃, 16 h light / 8 h dark culture), and the growth was observed and recorded. Various growth indicators were statistically analyzed.

[0090] 4. Results Analysis

[0091] like Figure 4 As shown, under pot culture conditions, plants inoculated with strain Pr38 were significantly taller, had higher fresh weight per plant, and greater leaf and stem width than the control group. Both the overall plant performance and individual plant performance indicated that plants inoculated with strain Pr38 showed better growth than the uninoculated group.

[0092] Example 5: Co-cultivation of Pr38 microbial fertilizer and potted rice seedlings

[0093] 1. Activation culture of bacterial strains

[0094] The Pr38 strain preserved on the slant was inoculated onto potato dextrose agar (PDA) solid medium for activation culture, and cultured in the dark at 25°C for 7 days for later use.

[0095] 2. Preparation of Pr38 solid microbial fertilizer

[0096] Endophytic fungal Pr38 mycelial blocks (0.5 cm in diameter) cultured for 7 days were placed in PDB liquid fermentation medium (containing 5 g potato extract, 10 g peptone, and 15 g glucose per 1000 mL) for fermentation (25℃, 150 rpm, 7 days). The fermentation liquid was then inoculated onto sterilized barley grains (150 mL / 200 g inoculation amount) and incubated in the dark for 15 days until the barley grains were fully covered with mycelium, yielding Pr38 solid microbial fertilizer.

[0097] 3. Co-cultivation of Pr38 microbial fertilizer and potted rice seedlings

[0098] (1) Application of solid microbial fertilizer: Mix the fermented solid microbial fertilizer with the seedling substrate and use it as new substrate soil for rice pot cultivation. Soak rice seeds (Zhejiang Jing 99) in 1.5% sodium hypochlorite for 10 min for surface disinfection, then rinse with water 5-6 times, and then place them in a 37℃ dark constant temperature incubator for 12 days to germinate. When the seeds show white sprouts, sow them evenly in the pots.

[0099] (2) Rice seedling pot culture: Rice was cultured in pots for 14 days (22-25℃, 16 h light / 8 h dark culture). During the culture period, the rice was irrigated with 60 mg / L cadmium solution (100 mL / time) 6 times. The growth was observed and recorded, and various growth indicators were statistically analyzed.

[0100] 4. Results Analysis

[0101] like Figure 5As shown, under pot culture conditions and cadmium stress of 60 mg / L, plants inoculated with strain Pr38 showed significantly higher plant height and fresh weight than the uninoculated control group. Both the overall plant performance and individual plant performance indicated that plants inoculated with strain Pr38 exhibited better growth than the uninoculated group.

[0102] The above description is merely a specific embodiment of the present invention, intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly, and should not be construed as limiting the scope of protection of the present invention. All equivalent modifications or substitutions made based on the essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. An endophytic fungus Pr38, characterized in that, The endophytic fungus Pr38 was isolated from the roots of Phragmites australis and classified as follows: Pezicula sp. Pr-38, deposited at the China Center for Type Culture Collection, accession number CCTCC NO: M20252460.

2. The endophytic fungus Pr38 as described in claim 1, characterized in that, The culture conditions for the strain were as follows: the endophytic fungus Pr38 was inoculated into PDA solid medium and cultured in the dark at 22-25℃ for 7-10 days.

3. A liquid microbial fertilizer containing endophytic fungi Pr38, characterized in that, The method for preparing the liquid microbial fertilizer includes: inoculating the endophytic fungus Pr38 as described in claim 1 into a liquid fermentation medium, culturing it until the medium is covered with mycelia, and obtaining the liquid microbial fertilizer. The liquid fermentation medium is composed of 5 g potato starch, 10 g peptone, and 15 g glucose per 1000 mL.

4. A solid microbial fertilizer containing endophytic fungi Pr38, characterized in that, The method for preparing the solid microbial fertilizer includes: inoculating the endophytic fungus Pr38 as described in claim 1 into a liquid fermentation medium, culturing to obtain a fermentation broth, then inoculating the fermentation broth onto sterile barley grains, mixing the fermentation broth and sterile barley grains at a ratio of 150 mL: 200 g, and culturing in the dark at 25°C until the mycelium grows and covers the barley grains, thereby obtaining Pr38 solid microbial fertilizer; the liquid fermentation medium is composed of 5 g potato starch, 10 g peptone, and 15 g glucose per 1000 mL.

5. The application of the endophytic fungus Pr38 as described in claim 1 in promoting tomato growth, characterized in that, The application includes co-culturing the endophytic fungus Pr38 with tomato plants.

6. The application as described in claim 5, characterized in that, The indicators for tomato growth include plant fresh weight, plant height, leaf width, and stem width.

7. The application of the endophytic fungus Pr38 as described in claim 1 in improving the tolerance of rice to cadmium stress, characterized in that, The application includes co-culturing the endophytic fungus Pr38 with rice plants.

8. The application as described in claim 7, characterized in that, The application includes: co-culturing rice seeds with the endophytic fungus Pr38 after germination, allowing it to colonize the roots of rice seedlings, thereby improving the tolerance of rice seedlings to cadmium stress.

9. The application as described in claim 8, characterized in that, The application includes: preparing endophytic fungus Pr38 into solid microbial fertilizer, mixing it into a seedling substrate to obtain a mixed substrate, and sowing rice seeds in the mixed substrate after germination to obtain rice seedlings.

10. The application as described in claim 7, characterized in that, The co-culture conditions are: 22-25℃, 16 h light / 8 h dark culture.

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