Endophytic fungus LW111 and application thereof

Abstract

The invention discloses an endophytic fungus LW111 and application thereof, and belongs to the technical field of microorganisms. The endophytic fungus LW111 is classified and named as Magnaporthaceae sp.LW111, and is preserved in the China Center for Type Culture Collection (CCTCC), and the preservation number is CCTCC NO: M 20241750. The endophytic fungus LW111 is co-cultured with rice, so that the endophytic fungus LW111 is colonized in the root tissue of the rice, the tolerance of rice plants to cadmium, especially in the seedling stage, can be enhanced, and the growth of the plants is promoted. Therefore, the endophytic fungus LW111 has popularization and application values in the aspects of guaranteeing plant health and improving rice seedling stage growth.

Description

Technical Field

[0001] The invention relates to the technical field of microorganisms, and in particular to an endophytic fungus Magnaportheaceae sp. LW111 and application thereof in improving the tolerance of rice to cadmium and promoting the growth of rice. Background Art

[0002] Cadmium (Cd) is one of the most toxic heavy metal elements. With the rapid development of industrialization, urbanization and intensive agricultural production in my country, the problem of heavy metal pollution in farmland has become increasingly serious, seriously restricting the sustainable development of agriculture. As a non-essential element for plants, cadmium does not participate in the structure and metabolic activities of organisms and can be toxic to plants even at low concentrations. Under cadmium stress conditions, rice growth is slow, seedlings are dwarfed, root volume is reduced, and dry matter accumulation is reduced, which seriously affects rice production.

[0003] In recent years, more and more research has been conducted on the application of endophytic fungi in plant stress resistance, especially in resistance to heavy metal stress. Endophytic fungi are a special type of microorganisms that are beneficial to plants. After colonizing in plants, these fungi do not cause diseases, but can promote the growth of host plants and improve their resistance to stress, such as heavy metal tolerance. At the same time, some endophytic fungi can also reduce the amount of pathogens in plants by having adverse effects on pathogens, thereby inhibiting or alleviating the development of diseases.

[0004] For example, endophytic fungi Colonization promotes arbuscular mycorrhizal fungal infection, which can alleviate the toxic effects of cadmium stress on Drunken Horse Grass and improve its resistance to diseases and pests (Zhao Zhenrui et al. Effects of interactions between endophytic fungi and arbuscular mycorrhizal fungi on the growth and cadmium tolerance of Drunken Horse Grass seedlings. Grassland Science, 2020, 37(3): 432-443.).

[0005] Endophytic fungi of Suaeda salsa can significantly improve the resistance of rice to cadmium and salt stress after being inoculated into rice (Mei Yingxue. Effects of endophytic fungus Gao Y1-1 of Suaeda salsa on endogenous hormones and organic acid content in rice seedlings under cadmium and / or aluminum stress. 2017), indicating that some endophytic fungi can survive between different host plants and improve the cadmium resistance of host plants.

[0006] Inoculation of the dark septate endophytic fungus Acrocalymma vagum into tobacco roots can significantly reduce the heavy metal content in tobacco leaves (Hui-Qing Jin, et al. Effect of the dark septate endophytic fungus Acrocalymma vagum on heavy metal content in tobacco leaves. Symbiosis, 2018, 74: 89-95.).

[0007] The use of endophytic fungi to improve plant stress resistance has broad application prospects. Therefore, the development of new safe and effective endophytic fungi and the use of their interaction with rice to improve rice's resistance to heavy metal cadmium are of great significance for agricultural production. Summary of the invention

[0008] The purpose of the present invention is to provide an endophytic fungus strain capable of improving the tolerance of rice to cadmium, so as to solve the problem of limited growth of rice in cadmium-contaminated soil.

[0009] To achieve the above object, the present invention adopts the following technical solution:

[0010] The present invention isolates a new strain belonging to the genus Magnaporthe from the root system of wild rice, and the main biological characteristics of the strain are: the colony diameter is 6 cm after growing at 25°C for 7 days on a PDA plate; the aerial hyphae are not well developed, creeping on the surface of the culture medium, the colony is dark brown, the hyphae are transparent or dark brown, and the width is 1.0-2.5 μm; and the strain does not produce spores. The ITS sequence of the endophytic fungus is shown in SEQ ID NO.1. By constructing a phylogenetic tree, it is identified that the strain belongs to the kingdom Fungi, the phylum Ascomycota, the class Sordariomycetes, the order Magnaportheales, the family Magnaporthaaceae, and the genus Magnaporthe. Therefore, it was named: Magnaportheaceae sp.LW111, and was deposited in the China Center for Type Culture Collection on August 5, 2024, with the deposit address: Wuhan University, Wuhan, China, and the deposit number is CCTCC NO: M 20241750.

[0011] The culture conditions of the endophytic fungus LW111 strain are as follows: the endophytic fungus LW111 is inoculated into a PDA solid culture medium and cultured in the dark at 22-25° C. for 5-10 days.

[0012] The present invention also provides a preparation form of the endophytic fungus LW111, which is prepared into a solid bacterial fertilizer. The preparation method comprises: inoculating the endophytic fungus LW111 into a liquid fermentation medium, culturing to obtain a fermentation liquid, then inoculating the fermentation liquid onto sterile barley grains, culturing in the dark until mycelium grows and covers the barley grains, thereby obtaining the LW111 solid bacterial fertilizer; the composition of the liquid fermentation medium is: 5g potato extract powder, 10g peptone, and 15g glucose per 1000mL.

[0013] Preferably, the fermentation liquid and sterile barley grains are mixed in a ratio of 200 mL:300 g, and cultured in the dark at 25° C. until mycelium grows and covers the barley grains, thereby obtaining LW111 solid bacterial fertilizer.

[0014] The solid bacterial fertilizer can be applied in the following manner: the solid bacterial fertilizer is mixed into a seedling medium, and the germinated crop seeds are sown in the seedling medium containing the endophytic fungus LW111. During the seedling raising process, the endophytic fungus LW111 colonizes the roots of the plant seedlings.

[0015] The present invention found that colonizing Magnaportheaceae sp. LW111 in rice root tissue can significantly promote the growth of rice seedlings in cadmium-contaminated soil and enhance the tolerance of rice seedlings to cadmium.

[0016] Therefore, the present invention provides the use of the endophytic fungus LW111 in improving the tolerance of rice to cadmium stress.

[0017] The application comprises: colonizing the endophytic fungus LW111 in the root tissue of rice.

[0018] Preferably, the application comprises: co-culturing rice seeds with the endophytic fungus LW111 after germination, so that the endophytic fungus LW111 colonizes the roots of rice seedlings, so as to improve the tolerance of rice seedlings to cadmium stress.

[0019] Preferably, the application comprises: preparing the endophytic fungus LW111 into a solid fertilizer, mixing the fertilizer into a seedling medium to obtain a mixed medium, and sowing the rice seeds in the mixed medium for seedling cultivation after germination to obtain rice seedlings.

[0020] The LW111 strain is grown together with rice seedlings in the form of bacterial fertilizer, so that it can colonize at the roots of rice seedlings, which can significantly promote the growth of rice seedlings under cadmium stress conditions.

[0021] Preferably, the co-cultivation conditions are: 22-25°C, 16h light / 8h dark cultivation.

[0022] The present invention also provides an application of the endophytic fungus LW111 in promoting rice growth, and the application comprises: colonizing the endophytic fungus LW111 in rice root tissue.

[0023] The present invention shows that the interaction between the endophytic fungus LW111 and rice seedlings can significantly improve the growth performance of rice seedlings, whether under cadmium stress or cadmium-free stress. Specifically, the rice growth indicators include plant fresh weight, plant height, leaf width, stem width, and chlorophyll content.

[0024] The present invention has the following beneficial effects:

[0025] The present invention provides a new endophytic fungus of the genus Magnaporthe, which can significantly promote the growth of rice under cadmium stress by interacting with rice. The endophytic fungus LW111 is co-cultured with rice to colonize the root tissue of rice, which can enhance the tolerance of rice plants, especially in the seedling stage, to cadmium and promote plant growth. Therefore, the endophytic fungus LW111 has a popularization and application value in terms of ensuring plant health and improving the growth of rice seedlings. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is the phylogenetic tree of the LW111 strain.

[0027] Figure 2 This is a test for the plate growth and cadmium resistance of the LW111 strain.

[0028] Figure 3 The hyphae morphology of LW111 strain under different microscope fields.

[0029] Figure 4 The colonization of LW111 strain after co-cultivation with rice (Trypan blue staining method). The arrows in the figure indicate the stained hyphae structure observed in the rice root section.

[0030] Figure 5 is the effect of LW111 strain on rice cadmium tolerance. Where ac is the effect of LW111 strain on the fresh weight of rice seedlings under different concentrations of cadmium stress; df is the effect of LW111 strain on the stem width of rice seedlings under different concentrations of cadmium stress. The bar graph represents the mean ± standard deviation, n = 9. Significant difference (one-way analysis of variance using Tukey's method for multiple comparisons): * represents P < 0.05, ** represents P < 0.01, *** represents P < 0.001, **** represents P < 0.0001, ns represents no significance. Where Control represents the control, LW111 represents the inoculated strain LW111. gi represents the growth status of rice seedlings colonized with LW111 strain and uninoculated strains under different cadmium concentrations.

[0031] Figure 6 The effect of LW111 strain on cadmium tolerance of potted rice seedlings. a is the effect of LW111 strain on the growth of potted rice seedlings; b is the effect of LW111 strain on the growth of single potted rice seedlings; ch is the effect of LW111 strain on the growth index of potted rice seedlings under cadmium stress. The bar graph represents the mean ± standard deviation, n = 9. Significant difference (one-way analysis of variance using Tukey's method for multiple comparisons): * represents P < 0.05, ** represents P < 0.01, *** represents P < 0.001, **** represents P < 0.0001, ns represents no significance. Control represents the control. DETAILED DESCRIPTION

[0032] The present invention will be further described below in conjunction with specific embodiments. The following embodiments are only used to illustrate the present invention and are not intended to limit the scope of application of the present invention. Without departing from the spirit and essence of the present invention, modifications or replacements made to the inventive method, steps or conditions all belong to the scope of the present invention.

[0033] Unless otherwise specified, the experimental methods used in the following examples are all conventional methods; the materials and reagents used are reagents and materials that can be obtained from commercial channels unless otherwise specified.

[0034] Example 1: Isolation, purification and identification of endophytic fungus strain LW111

[0035] 1. Strain Isolation and Purification

[0036] The endophytic fungus LW111 was isolated from the roots of wild rice in Yunnan. The specific isolation method is as follows: First, rinse the wild rice roots continuously with tap water, and carefully remove soil particles and appendages. Select healthy root tissue, disinfect the surface, soak in 75% ethanol for 1-2 minutes, 1% sodium hypochlorite for 4-5 minutes, and then wash with sterile deionized water 3 times. Cut the root tissue blocks into 0.5 cm small segments, and then incubate them on a 2% malt extract agar medium (MEA, malt extract agar, OXOID; 50 mg / L chloramphenicol was added to the culture medium to inhibit the growth of endophytic bacteria) plate, and culture in the dark at 25°C. On the 5th day of culture, endophytic fungal hyphae grew from the edge of the tissue incision. Carefully pick it out with an inoculation needle and transfer it to fresh PDA medium for purification and culture, and record the strain number LW111.

[0037] PDA medium: 20 g / L glucose, 200 g / L potato, 15 g / L agar. Weigh the required potato (200 g / L) according to the volume of the medium to be prepared, boil it in water, mash it to dissolve, filter it, add glucose and agar, and sterilize it with high pressure steam at 121°C for 20 minutes.

[0038] 2. Strain Identification

[0039] 1. Morphological identification

[0040] After the LW111 strain was isolated and purified, it was inoculated on PDA medium and cultured at 25°C for 7 days. A small amount of bacteria was picked up with a needle, made into a slide, and observed and measured under a microscope. Figure 2 , Figure 3As shown, its morphological characteristics are: the colony grows faster on the PDA plate, and the colony diameter is 6 cm after growing at 25°C for 7 days; the aerial hyphae are not well developed, creeping on the surface of the culture medium, the colony is dark brown, the hyphae are transparent or dark brown, and are 1.0-2.5μm wide; it does not produce spores.

[0041] 2. Molecular identification

[0042] (1) DNA extraction

[0043] ① After culturing the LW111 strain on a PDA plate at 25°C for 7 days, scrape the mycelium on the plate with a toothpick and place it in a sterilized centrifuge tube containing 300 μL extraction buffer (1M KCl, 100mM Tris HCl, 10mM EDTA, pH=8.0);

[0044] ② Grind with an electric grinder and shake vigorously for 2 minutes;

[0045] ③ Centrifuge at 10000 rpm for 10 min;

[0046] ④ Aspirate the supernatant, transfer it to another new centrifuge tube, and discard the precipitate;

[0047] ⑤ Add an equal volume of isopropanol (analytical grade) to the supernatant, gently invert several times to mix, and centrifuge at 12000 rpm for 10 min to precipitate the nucleic acid;

[0048] ⑥ Gently pour off the supernatant and invert the centrifuge tube containing the precipitate on absorbent paper to drain the water;

[0049] ⑦ Add 300 μL of 70% ethanol, gently invert several times to mix, and centrifuge at 12000 rpm for 2 minutes;

[0050] ⑧Gently pour off the supernatant and repeat step ⑦ once;

[0051] ⑨ Invert the centrifuge tube on absorbent paper to drain the water, and place it at 37℃ for 15 minutes to allow the ethanol to evaporate completely;

[0052] ⑩ Resuspend the precipitate with 50 μL ddH2O to obtain LW111 genomic DNA with a concentration of 30 ng / μL.

[0053] (2) PCR amplification of fungal ITS rDNA genes

[0054] PCR amplification was carried out in a 50 μL reaction system, which contained: 2 μM each of upstream and downstream primers, 200 μM dNTPs, 1.5 mM MgCl2, 5 μL 10×PCR buffer, 2 μL template DNA, and 2 U Taq enzyme.

[0055] The sequence of the upstream primer ITS1 is: 5'-TCCGTAGGTGAACCTGCGG-3',

[0056] The sequence of the downstream primer ITS4 is: 5'-TCCTCCGCTTATTGATATGC-3'.

[0057] PCR amplification was performed on a Longji MG96G PCR instrument. Reaction conditions: 94°C pre-denaturation for 2 min, then 35 cycles including: 94°C denaturation for 30 sec, 55°C annealing for 40 sec, 72°C extension for 1 min, and finally 72°C extension for 10 min.

[0058] (3) Recovery and purification of PCR products

[0059] After the PCR reaction was completed, the PCR product was detected by 1% agarose gel electrophoresis and then purified using a DNA gel purification kit from Aisheng Biotechnology Company according to the steps in the kit manual.

[0060] (4) Gene sequencing and sequence analysis

[0061] The purified and recovered target DNA fragments after electrophoresis were sent to the Hangzhou Sequencing Department of Youkang Biological Company for sequencing. After strict verification of the sequencing results, a DNA fragment sequence with a length of 559 bp as shown in SEQ ID NO.1 was obtained.

[0062] On the NCBI website, the measured nucleotide sequence was searched and compared with homologous or similar nucleotide sequences in the GenBank database using BLAST. After BLAST comparison, the sequence had a coverage rate of 85% and a similarity of 100% with the sequence with accession number MW055631.1, which was from the ITS rDNA sequence of Magnaportheaceae sp. strain YNE00478.

[0063] Phylogenetic tree ( Figure 1 ) showed that LW111 was more closely related to Falciphora than to Magnaporthe. The support between LW111 and the nodes within Falciphora was relatively low, so it was not appropriate to directly classify it as Falciphora. Based on the results of nucleotide sequence and phylogenetic tree, it was considered that LW111 was a new strain belonging to Magnaporthe that had not yet been identified.

[0064] The above molecular identification and morphological identification results showed that the strain belongs to Fungi, Ascomycota, Sordariomycetes, Magnaportheales, Magnaportheaceae, and Magnaporthe. Therefore, it was named: Magnaportheaceae sp.LW111, and was deposited in the China Center for Type Culture Collection on August 5, 2024, with the deposit address: Wuhan, China, Wuhan University, and the deposit number is CCTCC NO: M20241750. The collection center identified it as alive on August 12, 2024.

[0065] Example 2: Tolerance of endophytic fungus LW111 to cadmium stress

[0066] 1. Strain activation culture

[0067] The LW111 strain stored on the slant was inoculated on potato dextrose agar (PDA) solid medium for activation culture, cultured at 25°C in the dark for 7 days, and set aside.

[0068] PDA medium: Each liter contains 20g glucose, 200g potato, and 15g agar. Weigh the required potatoes according to the volume of the medium to be prepared, boil them in water, mash them to dissolve, filter them, add glucose and agar, and sterilize them with high-pressure steam at 121℃ for 20 minutes.

[0069] 2. Detection of the tolerance of LW111 strain under cadmium concentration gradient

[0070] The cadmium ion concentrations in the PDA medium were 0 mg / L, 1 mg / L, 2 mg / L, and 3 mg / L. The strain LW111 was inoculated on PDA medium with different cadmium concentration gradients and cultured at 25°C in the dark for 7 days.

[0071] 3. Results Analysis

[0072] like Figure 2 As shown, different Cd 2+ The concentration caused significant differences in the colony morphology of LW111. Under cadmium-free conditions, the colonies were brown with white aerial hyphae. As the cadmium concentration increased, the colonies gradually turned white as a whole and the colony diameter gradually decreased. When the cadmium concentration was 1 mg / L, the colony diameter became smaller and the color hardly changed. When the cadmium concentration was 2 mg / L, the colony diameter was even smaller and the overall color turned white. When the cadmium concentration was 3 mg / L, the colony growth was completely inhibited.

[0073] Example 3: Endophytic fungus LW111 promotes rice growth under cadmium stress

[0074] 1. Strain activation culture

[0075] The LW111 strain stored on the slant was inoculated on potato dextrose agar (PDA) solid medium for activation culture, cultured at 25°C in the dark for 7 days, and set aside.

[0076] 2. Co-cultivation of strain LW111 and rice

[0077] After the CO39 rice seeds were shelled, they were sterilized with 75% ethanol for 10 minutes, then with 1% NaClO for 20 minutes, and finally washed with sterile water. After the seeds were sterilized, they were placed on 1 / 2MS medium for germination culture.

[0078] When the seeds turn white, select the seeds with the same growth. Use long tweezers to inoculate the seeds on 1 / 2MS medium in a 7cm diameter tissue culture bottle, 9 seeds per bottle. Use an inoculation loop to evenly inoculate the bacterial cake of strain LW111 around the rice seeds, and inoculate sterile PDA blocks as the control group. Set different cadmium concentration gradients in 1 / 2MS medium, which are 0μM, 7μM, and 10μM. Culture in a 25℃ constant temperature and light incubator, 16h light / 8h dark. Observe the results after 14 days of co-cultivation.

[0079] Note: MS medium (1L): potassium nitrate 1900mg / L, ammonium nitrate 1650mg / L, magnesium sulfate 370mg / L, potassium dihydrogen phosphate 170mg / L, calcium chloride 440mg / L, manganese sulfate 22.3mg / L, zinc sulfate 8.6mg / L, boric acid 6.2mg / L, potassium iodide 0.83mg / L, sodium molybdate 0.25mg / L, copper sulfate 0.025mg / L, cobalt chloride 0.025mg / L, ferrous sulfate 27.8mg / L, Na2EDTA 37.3mg / L, glycine 2.0mg / L, thiamine hydrochloride 0.1mg / L, pyridoxine hydrochloride 0.5mg / L, niacin 0.5mg / L, inositol 100mg / L, sucrose 30g, agar powder 8g, H2O made up to 1L; pH value 5.8. 1 / 2MS medium is the MS medium with the content of major elements reduced by half and the content of other elements unchanged.

[0080] 3. Colonization observation of strain LW111 (Trypan blue staining method)

[0081] After the strain LW111 and rice were co-cultured in the tissue culture bottle for 14 days, the rice roots were taken out and the culture medium attached to the roots was washed off with clean water. The root tissue was dried with absorbent paper, and 1 cm root segments were cut and placed in 2 mL centrifuge tubes.

[0082] Add 1.8 mL of 5% KOH, mix well, and place in a 90°C water bath for 10 min. Discard the waste liquid, rinse the root segments with ddH2O, and dry with absorbent paper.

[0083] Add 1.8 mL of alkaline H2O2 (prepared and used immediately), mix well, and leave at room temperature for 15 min. Discard the waste liquid, rinse the root segments with ddH2O, and dry with absorbent paper.

[0084] Add 1.8 mL of 2% HCl, mix well, and incubate at room temperature for 5 min. Discard the waste solution, rinse the root segments with ddH2O, and dry with absorbent paper.

[0085] Add 1.8 mL of 0.05% trypan blue dye, mix well, and place in a 90°C water bath for 60 min. Discard the waste liquid, rinse the root segments with ddH2O, and dry with absorbent paper.

[0086] For slide preparation, the processed root segments were placed on glass slides, sealed with 50% glycerol, and observed under an optical microscope.

[0087] 4. Results Analysis

[0088] like Figure 4 As shown, after strain LW111 was co-cultivated with rice for 14 days, stained hyphal structures could be observed in rice root sections, indicating that strain LW111 could colonize in rice roots.

[0089] like Figure 5 As shown in the figure, under the conditions of tissue culture flask culture, when there is no cadmium stress, the plants inoculated with LW111 strain grew stronger, and the fresh weight and stem width increased significantly. When the cadmium stress concentration was 7μM and 10μM, the fresh weight of the plants inoculated with LW111 strain was still significantly higher than that of the cadmium treatment group without bacteria.

[0090] Example 4: Co-cultivation of LW111 bacterial fertilizer and rice seedling potted plants

[0091] 1. Strain activation culture

[0092] The LW111 strain stored on the slant was inoculated on potato dextrose agar (PDA) solid medium for activation culture, cultured at 25°C in the dark for 7 days, and set aside.

[0093] 2. Preparation of LW111 solid bacterial fertilizer

[0094] The mycelium block (0.5 cm in diameter) of the endophytic fungus LW111 cultured for 7 days was placed in PDB liquid fermentation medium (containing 5 g potato powder, 10 g peptone, and 15 g glucose per 1000 mL) for fermentation culture (25°C, 150 rpm, 7 days). The fermentation liquid was then inoculated on sterilized barley grains (inoculation amount was 200 mL / 300 g), placed in an incubator for dark culture for 15 days, and LW111 solid bacterial fertilizer was obtained when the barley grains were fully covered with mycelium.

[0095] 3. Co-cultivation of LW111 bacterial fertilizer and rice seedling potted plants

[0096] (1) Application of solid bacterial fertilizer: Mix the fermented solid bacterial fertilizer with the seedling medium and use it as the new medium soil for rice potting. Soak the rice seeds (CO39) in 70% alcohol for 15 minutes to disinfect the surface, and then place them in a dark incubator at 37°C for 12 days to germinate. When the seeds turn white, sow them evenly in pots. From the start of sowing to the 6th day, water 100 mL / pot every other day. From the 6th to the 14th day after sowing, the treatment group used 10 μM Cd standard substance solution instead of water, and the control group was still watered, applied once every other day, with a dosage of 100 mL / pot.

[0097] (2) Rice seedling pot culture: Rice was cultured in pots for 14 days, and the growth conditions were observed and recorded, and various growth indicators were counted.

[0098] 4. Results Analysis

[0099] like Figure 6 As shown in the figure, under potted culture conditions, under no cadmium stress and 10μM cadmium stress, the height, leaf width, stem width and chlorophyll content of the plants inoculated with the LW111 strain were significantly higher than those of the control group. From the overall performance of the plants and the performance of individual plants, the growth of the plants inoculated with the LW111 strain was better than that of the non-inoculated group.

Claims

1. An endophytic fungus LW111, characterized in that The endophytic fungus LW111 was isolated from the root of wild rice, classified and named Magnaportheaceae sp.LW111, and deposited in the China Center for Type Culture Collection with the deposit number CCTCC NO: M20241750.

2. The endophytic fungus LW111 according to claim 1, characterized in that The strain culture conditions are as follows: the endophytic fungus LW111 is inoculated into a PDA solid culture medium and cultured in the dark at 22-25° C. for 5-10 days.

3. An endophytic fungus LW111 solid bacterial fertilizer, characterized in that: The preparation method comprises: inoculating the endophytic fungus LW111 as claimed in claim 1 into a liquid fermentation medium, culturing to obtain a fermentation liquid, then inoculating the fermentation liquid onto sterile barley grains, culturing in the dark until mycelium grows and covers the barley grains, and obtaining LW111 solid bacterial fertilizer; the composition of the liquid fermentation medium is: 5g potato extract powder, 10g peptone, and 15g glucose per 1000mL.

4. The endophytic fungus LW111 solid bacterial fertilizer according to claim 3, characterized in that: The fermentation liquid and sterile barley grains were mixed in a ratio of 200 mL: 300 g, and cultured in the dark at 25°C until the mycelium grew and covered the barley grains, thus obtaining LW111 solid bacterial fertilizer.

5. Use of the endophytic fungus LW111 according to claim 1 in improving the tolerance of rice to cadmium stress, characterized in that: The application comprises: colonizing the endophytic fungus LW111 in the root tissue of rice.

6. The use according to claim 5, characterized in that The application comprises: co-culturing rice seeds with the endophytic fungus LW111 after germination, so that the endophytic fungus LW111 is colonized in the roots of rice seedlings, so as to improve the tolerance of rice seedlings to cadmium stress.

7. The use according to claim 6, characterized in that The application comprises: preparing the endophytic fungus LW111 into solid bacterial fertilizer, mixing the fertilizer into a seedling medium to obtain a mixed medium, and sowing rice seeds in the mixed medium for seedling cultivation after germination to obtain rice seedlings.

8. The use according to claim 6, characterized in that The co-cultivation conditions are: 22-25° C., 16 h light / 8 h dark cultivation.

9. The use of the endophytic fungus LW111 in promoting rice growth according to claim 1, characterized in that: The application comprises: colonizing the endophytic fungus LW111 in the root tissue of rice.

10. The use according to claim 9, characterized in that The rice growth indicators include plant fresh weight, plant height, leaf width, stem width and chlorophyll content.

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