CN112266877B - Helminthosporium rosthornii mutagenesis and application thereof in preventing and treating moleplant seed - Google Patents

Abstract

The invention discloses a mutant Helminthosporium rosthornii and application thereof in preventing and treating moleplant seed. The strain is classified and named as Exserohilustratum Y9511-X050, the preservation number is GDMCC NO:60804, and the strain is preserved in Guangdong province microbial strain preservation center of No. 59 building and No. 5 building of Michelia Tokyo No. 100 college in Guangdong province, guangzhou City in 2019, 10 and 8 days. The strain is obtained by chemical mutagenesis of a Helminthosporium rosthornii Y9511 strain separated from a paddy field moleplant seed leaf, is safe and harmless to rice, has a control effect on moleplant seed, is safe in application, and is suitable for biological control of the paddy field moleplant seed.

Description

Helminthosporium rosthornii mutagenesis and application thereof in preventing and treating moleplant seed

Technical Field

The invention belongs to the field of microorganisms, and particularly relates to a mutant helminthosporium umbiliciformis strain and application thereof in preventing and treating moleplant seed.

Background

Weeds are important plant resources in an agricultural ecological system and compete with crops for water, nutrients, illumination and space; reducing the quality of the agricultural products; hampering crop harvesting; threatens the safety of world grain production and causes economic loss. Therefore, weed control has become a persistent problem in the field of agricultural production. Euphorbia lathyris (Leptochloachinensis (L.) Nees) is an annual grass weed of the genus Euphorbia. The distribution of the rice is almost spread over all main rice production areas in the world, china is mainly distributed in Yangtze river basin and all provinces in the south of the Yangtze river basin, and Shaanxi is also distributed. With the large-area popularization of the light cultivation technology of rice and the large use of selective herbicides, the weed community structure of the rice field is changed greatly, the moleplant seeds spread rapidly in the rice area in south, become malignant weeds second to barnyard grass, even harm to part of the rice field exceeds the barnyard grass, the growth and the yield of the rice are seriously influenced, and the rice field is seriously threatened to the grain safety.

The weed control strategy includes artificial weeding, mechanical weeding, cultivation measures, farming systems and the like, but the method mainly used at present is chemical weeding. The long-term widespread use of chemical herbicides has led to the development of resistant weed populations, and the large accumulation of herbicide residues in ecosystem has led to secondary environmental pollution that ultimately endangers human health. Therefore, the development of safe, highly effective, green and environmentally friendly bioherbicides has attracted considerable attention from weed scientists.

Compared with chemical herbicides, the microbial herbicide has the characteristics of abundant resources, difficult generation of resistant weeds, safety to non-target organisms, good economic benefit, good environmental compatibility and the like. Fungi, bacteria, viruses and actinomycetes are potential microbial resources that can be used in microbial herbicides. Many bioherbicides have been successfully commercialized, and these products help to solve problems associated with the prevention and control of certain malignant weeds. There are 13 bioherbicides on the market, globally, derived from microorganisms or natural molecules. However, there is a growing need for bio-herbicides based on the need to improve the efficiency of weed control, the development of organic agriculture and the growing public concern about environmental safety. Therefore, the rapid discovery and development of the biological herbicide have important practical value and profound significance for ensuring the sustainable development of agriculture.

Good strains of microorganisms are fundamental and critical to the fermentation industry, but wild-type microorganisms used directly as biologies often have some disadvantages, such as slow growth, low spore production, and low cost. Therefore, mutation breeding of microorganisms is essential for the development of fungal herbicides.

The invention aims to provide a mutant Helminthosporium rosthornii and application thereof in preventing and treating moleplant seed.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provide a strain of creeping rostellularia which is used for mutagenizing the creeping rostellularia.

The invention also aims to provide application of the mutant Helminthosporium rhynchophyllum.

The purpose of the invention is realized by the following technical scheme:

the strain of the mutant hirsutella ureafoensis is classified and named as Exserohilum rostratum Y9511-X050 with the preservation number of GDMCC NO:60804, and is preserved in Guangdong province microbial strain preservation center (GDMCC for short) of No. 59 building and No. 5 building of Tokyo Dazhou No. 100 college of Michelia Tokyo, guangzhou, guangdong province in 2019, 10 and 8 days.

The invention also provides spores of the mutant hirsutella sinensis.

The preparation method for mutagenizing the spores of the Helminthosporium rosthornii comprises the following steps: inoculating the mutant hirsutella himurium to a PDA culture medium, culturing at 28-30 ℃, and filtering to remove hyphae to obtain spores of the mutant hirsutella himurium.

The temperature of the culture is preferably 28 ℃.

The period of the cultivation is preferably 14 days.

The filtration is carried out by using gauze; preferably, the filtration is carried out with four layers of gauze.

The application of the mutant T.rostratum or the spores of the mutant T.rostratum in preparing the biological herbicide.

The grass is a moleplant weed; preferably, the plant is paddy field Euphorbia lathyris.

A biological preparation for biological control of Euphorbia lathyris comprises the active ingredients of the mutant Hippocampus japonicas and/or spores of the mutant Hippocampus japonicas.

The concentration of the spores of the mutant Helminthosporium urencidum in the biological preparation is 10 ⁵ ～10 ⁷ spore/mL; preferably 10 ⁶ spore/mL.

The biological preparation can also contain a carrier acceptable in the aspect of pesticide pharmacy; the carrier comprises an emulsifier, water and the like.

The emulsifier is preferably tween 80.

The concentration of the emulsifier in the biological preparation is 0.5 per mill of volume percentage.

The creeping rostellularia, the spores of the creeping rostellularia, and/or the application of the biological agent for the biological control of the moleplant seed in the control of the moleplant seed.

Compared with the prior art, the invention has the following advantages and effects:

(1) In order to solve the problems of environmental pollution and unsafe chemical prevention in the prior art, the invention provides a strain Y9511-X050 of induced Helminthosporium rostratum, wherein the strain is obtained by carrying out chemical mutagenesis on a Y9511 strain separated from a moleplant seed leaf in a paddy field, is safe and harmless to rice, has a prevention and treatment effect on the moleplant seed, has safety in application, and is suitable for biological prevention and treatment of the moleplant seed in the paddy field.

(2) The using method is simple and practical: the Helminthosporium rosthornii Y9511-X050 is prepared into an aqueous emulsion, and the process is simple and practical.

(3) The prevention and treatment effect is obvious and stable: the hirsutella rhynchophylla strain Y9511-X050 spore suspension has a remarkable prevention and removal effect on moleplant seeds in a two-leaf one-heart period, and the disease index of a pot experiment reaches more than 99%.

Drawings

The invention is further described with the aid of the accompanying drawings, in which, however, the embodiments do not constitute any limitation to the invention, and for a person skilled in the art, without inventive effort, further drawings may be derived from the following figures.

FIG. 1 shows that after the Helminthosporium rosthornii strain Y9511 is subjected to chemical mutagenesis, the optimal mutagenized strain is screened by considering the same weight of four indexes, utilizing the maximum principal component to sort and mapping the ordinal numbers one by one.

FIG. 2 is a spore morphology of the strain of Helminthosporium rosticti Y9511-X050 and the starting strain Y9511; wherein, the picture a is a Helminthosporium rosthornii strain Y9511; FIG. b shows a strain of Helminthosporium rosthornii Y9511-X050.

FIG. 3 is a hyphal morphology of a strain of Helminthosporium rosthornii Y9511-X050 and a starting strain Y9511 according to the present invention; wherein, the picture a is a Helminthosporium rosthornii strain Y9511; FIG. b shows a strain of Helminthosporium rosthornii Y9511-X050.

FIG. 4 is a colony morphology of the strain Y9511-X050 and the starting strain Y9511 of Helminthosporium rosthornii according to the present invention; wherein, the picture a is a Helminthosporium rosthornii strain Y9511; FIG. b shows a strain of Helminthosporium rosthornii Y9511-X050.

FIG. 5 is a rice safety map of Helminthosporium rosticti strain Y9511-X050 and starting strain Y9511; wherein, the picture a is a Helminthosporium rosthornii strain Y9511; FIG. b shows a strain of Helminthosporium rosthornii Y9511-X050.

Detailed Description

The invention is further described with reference to the following examples.

The present invention will be described in further detail with reference to examples, but the embodiments of the present invention are not limited thereto. The reagents, methods and equipment used in the present invention are conventional in the art unless otherwise specified. Unless otherwise specified, the reagents, culture media and the like used in the present invention are commercially available; wherein:

the PDA culture medium formula is as follows: potato Dextrose Agar (PDA) 40.1g,5g agar, dissolved with 1L water.

The potato sucrose liquid culture medium comprises the following components: taking 250g of potatoes, boiling the potatoes in cold water, filtering the potatoes by using gauze to obtain filtrate, and determining the volume of the filtrate to 1000mL.

Example 1 mutagenic screening of strains of Helminthosporium rosthornii

1. Screening of Helminthosporium rosthornii at optimum time for mutagenesis

Picking mycelium of Helminthosporium umbiliciforme Y9511 cultured on a flat plate for 5 days and in a place with vigorous growth around the colony with a sampler, inoculating into a potato sucrose liquid culture medium containing a proper amount of glass beads, and performing shake culture at 28 ℃ for 48h at a rotation speed of 200r/min. Taking out, sucking 10mL of bacterial liquid, and fully grinding in a sterile grinder to obtain the mycelium suspension. Adding 0.2mol/L acetic acid buffer solution with pH of 4.6 2mL into test tube, adding 1mL mycelium suspension, shaking, immediately adding 1mL 0.2mol/L sodium nitrite solution, mixing to make the treated concentration of nitrous acid 0.05mol/L, acting at room temperature for 5min, 10min, 15min, 20min, 25min, 30min, 35min, 40min, respectively, adding 0.07mol/L Ph 8.6Na ₂ HPO ₄ The solution is 2mL to stop the reaction, 0.1mL of bacterial liquid of different treatments is respectively absorbed and coated on a PDA plate, 4 parallel samples in each group are compared with a hypha suspension liquid without chemical mutagenesis, the lethality is calculated after the hypha suspension liquid is cultured for at least 3d (days) under the dark condition at the temperature of 28 ℃, the counting is avoided because the hypha body is mutually cross-linked after the bacterial colony grows up, and the optimal mutagenesis time range is determined according to the lethality. After the colony in the optimal mutagenesis time range grows out, an equal amount of bacterial blocks are taken along the vigorous growing position of the outer edge of the colony by using a sterile glass puncher and are transferred to the central position of a PDA plate, and 51 bacterial strains are bred, wherein the bacterial strains are numbered as Y9511-X001, Y9511-X002, Y9511-X003 … … Y9511-X049, Y9511-X050 and Y9511-X051.

TABLE 1 optimal time frame for chemical mutagenesis in relation to mortality

Note: the data in the table are mean ± sem, with significant differences p < 0.05 for different upper and lower case letters (see below).

As shown in Table 1, when the chemical mutagenesis time is 20min, the mutagenesis mortality is 75% (the mutagenesis mortality is between 70% and 80%, and is the optimal mortality), so 20min is selected as the optimal mutagenesis time.

2. Screening of high-pathogenicity mutagenesis Helminthosporium rosthornii bacterial strain

By analyzing the original strain and the mutant strain, four indexes are as follows: 1. growing 1 d-4 d colony diameters on the plate; 2. 14d spore yield; 3. the size of the lesion of the isolated leaf; 4. disease index 7 d. Selecting strains with fast growth, more (and) produced spores, fast infection and large disease spots, and inoculating the strains on a slant. The slant was stored at 4 ℃ in preparation for rescreening.

Colony diameter: measured with a ruler (table 2,3,4,5);

sporulation yield: the hemacytometer measured the number of spores under the microscope (table 6);

the size of the lesion of the isolated leaf is as follows: the lesion size was measured after inoculating spore suspension on excised leaves for 3d (table 7);

disease index: culturing 51 mutagenic strains on PDA for 14 days, washing with 0.5 ‰ (v/v) Tween 80 water solution from the culture dish, filtering with four layers of gauze to remove mycelium to obtain spore suspension with concentration of 1.0 × 10 ⁶ spore/mL (counted with a hemocytometer), sprayed on live Euphorbia lathyris in two to three-leaf one-heart stage, and the treated live Euphorbia lathyris was subjected to moisture-retaining culture for 48h with the starting strain as a control, and then transferred into a greenhouse for growth, and each treatment was repeated 4 times. And 7d, grading and checking the disease incidence, and finally calculating and recording the disease index as a result of measuring the pathogenicity of the strain living body. As shown in table 8 (only data are listed in the table for significantly higher virulence than the starting strain).

Grading standard of the moleplant seed diseases:

level 0: the whole plant is disease-free, and the leaves are spot-free;

level 1: only small needle-tip-sized brown spots;

and 2, stage: the whole leaf has larger brown spots, and typical or oval necrotic lesions with the size of about 1-2 mm are uniformly distributed on the leaf and occupy about 2% of the leaf area;

and 3, level: the whole plant has typical scabs, and the infection area is less than 10 percent;

4, level: the whole plant has typical scabs, and the infection area accounts for about 10-50%;

and 5, stage: the whole plant has typical scabs, and the infection area accounts for about 51-75%;

and 6, level: the whole plant has typical lesion spots, and all leaves die.

In the formula, i represents disease grade, N represents the number of plants with disease of i grade, N represents the total number of investigated plants, and 6 represents the highest grade of plant disease. TABLE 2 significant analysis of 1d colony growth differences between the starting strain and 51 mutagenized strains on PDA medium

Note: the data in the table are mean ± sem, with significant differences p < 0.05 for different case letters.

TABLE 2 significant analysis of 1d colony growth differences between the starting strain and 51 mutagenized strains on PDA medium

Note: the data in the table are mean ± sem, with significant differences p < 0.05 for different case letters.

TABLE 3 significant analysis of the differences in colony growth between the starting strain and 51 mutagenized strains on PDA medium at 2d

Note: the data in the table are mean ± sem, with significant differences p < 0.05 for different case letters.

TABLE 4 significant analysis of the differences in colony growth between the starting strain and the 51g mutagenized strain on PDA medium at 3d

Note: the data in the table are mean ± sem, with significant differences p < 0.05 for different case letters.

TABLE 5 significant analysis of colony growth differences between the starting strain and 51 mutagenized strains on PDA medium at 4d

Note: the data in the table are mean ± sem, with significant differences p < 0.05 for different case letters.

TABLE 6 significant analysis of 14d sporulation difference between the starting strain and 51 mutagenized strains

Note: the data in the table are mean ± sem, with significant differences p < 0.05 for different case letters.

TABLE 7 determination of the pathogenicity of the original strain and 51 mutagenized strains to the detached leaf of Euphorbia lathyris

Note: the data in the table are mean ± sem, with significant differences p < 0.05 for different case letters.

TABLE 8 disease indices of the starting strains and 51 mutagenized strains on live Euphorbia lathyris (indoor assay)

Note: the data in the table are mean ± sem, with significant differences p < 0.05 for different case letters.

According to 4 criteria of the strain after mutagenesis: and (4) comprehensively considering the colony diameter, the sporulation quantity, the size of the lesion of the in vitro leaf and the disease index, and screening out the strain with the optimal property. For the 4-index above, we consider the same weights. Because the distribution of each index is different and not equal (uniform), we calculate the ordinal number (i.e. rank) of each index for more analysis later. Because of the obvious correlation (correlation) among various indexes, the method of Principal Component Analysis (PCA) is adopted to find the maximum principal component, and the quality of the strain character is measured according to the maximum principal component. We rank the maximum principal components of the 4 indexes of the strains and map (mapping) the ordinal numbers to (0,1) score intervals one by one, the closer the score is to 1, the better the strain character is. To check the sensitivity (sensitivity) between each observation and the final score, we perturbed (perturbation) each observation within its biologically reasonable range of values using the Monte Carlo, MC, method. The stability of the final score of the strain was checked and a 95% confidence interval (95% CI) was generated.

Example 2 genetic stability of P.rostratus strain Y9511-X050

Transferring the screened mutant strain of the Helminthosporium uredoides to an inclined plane, and transferring the mutant strain to a fresh PDA culture medium for culture after the mutant strain grows for 3-4 days, wherein the mutant strain is used as the 1 st generation; the above procedure was repeated until passage 10, and the colony growth diameter (4 d), spore yield (14 d) and disease index to Euphorbiae Lathyridis at 7d after spraying were determined for each generation of the strain (Table 9).

TABLE 9 genetic stability of Helminthosporium aurantiaca Y9511-X050

Note: the data in the table are mean ± sem, with significant differences p < 0.05 for different case letters.

As shown in Table 9, the colony diameter length of each generation is stable after 10 generations of subculture of the Helminthosporium rosthornii strain Y9511-X050; the conidium yield is not degenerated and basically kept stable; has better inhibiting effect on the moleplant seed (the method is the same as the disease index survey of the example 1), and the disease index is not degenerated. The results show that the mutant Helminthosporium rosthornii strain Y9511-X050 has good genetic stability.

Example 3 identification of strains of Helminthosporium rostratum

1. Morphological characteristics of Verticillium rosthornii strain Y9511-X050

(1) Inoculating strains Y9511 and Y9511-X050 on a PDA culture medium by adopting a culture dish culture method, culturing at 28 ℃, performing monospore separation after the tissue grows out of the mycelia, and selecting single colonies to be purified on the PDA culture medium for classification and identification. The purified strain is picked on a glass slide with a proper amount of sterile water, the strain morphology is observed on a microscope line, the starting strain Y9511 is used as a reference, the spore and hypha morphologies of the strain are shown in figures 2 and 3, the Y9511 mycelium is gray brown to black brown, and has irregular branches, 50-120 x 12-22 mu m of conidiospore, multiple diaphragms, most of 6-15 diaphragms, bent knee-shaped extension at the top end, slightly thicker at the middle lower part, long beak-shaped, blunt circles at two ends, lighter colors at two ends, the periphery of the umbilical point and the top end, as seen from figures 2a and 3 a. As can be seen from FIGS. 2b, 3b, unlike Y9511, the conidia of Y9511-X050 are 50-122X 10-22 μm, and hyphae and conidia are darker than those of the original strain Y9511.

(2) The purified strain was picked up and cultured on a new PDA medium at 28 ℃ for 14 days, and the colony morphology and colony color were observed as shown in FIGS. 4a and 4b. The colony of the Helminthosporium rostellum Y9511 and the colony of the Helminthosporium Y9511-X050 are round and spread, aerial hyphae exist, the hyphae in the initial stage is white and then turns into grey brown to black brown, sporulation starts after about 7d, the central spores of the colony gradually increase along with the time until the central spores spread to the edge, and the edge of the colony is still grey brown; the back of the colony is also gray black. The difference is that the aerial hyphae of Y9511 are longer, while those of Y9511-X050 are shorter.

2. Molecular biological identification of Helminthosporium rosthornii strain Y9511-X050

(1) Extraction of genomic DNA was performed according to SK8259 (fungi) kit.

(2) PCR amplification

And (3) PCR reaction system:

reagent	Volume (μ l)
		Template (genome DNA 20-50 ng/. Mu.l)	0.5
10×Buffer(with Mg 2+ )	2.5
		dNTPs (2.5 mM each)	1
Enzyme	0.2
		ITS1 or ITS1 (10 uM)	0.5
ITS2 or ITS2 (10 uM)	0.5
		Double steam adding H 2 O to	25

PCR cycling conditions:

(3) Using primers

ITS1：5’-AGAAGTCGTAACAAGGTTTCCGTAGG-3’；

ITS2：5’-GCTGCGTTCTTCATCGATGC-3’；

And

Brn1：5’-GCCAACATCGCAAACATGG-3’；

Brn2：5’-GCAAGCAGCACCGTCAATACCAAT-3’。

the ITS and Brn sequences of the strains Y9511 and Y9511-X050 are amplified by taking genomic DNA of the strains as templates to be 257bps,860bps and 268bps,860bps respectively, the amplified sequences of the strains are uploaded to an NCBI website for BLAST alignment analysis, and the result shows that the homology of the ITS and Brn gene sequences of the strains Y9511-050 to the Hippocampus japonicas (Exserohilum) is 99.40%. The strain is identified as the Helminthosporium rostellum by observing the form of conidium and hyphae of the strain Y9511 and identifying the molecular. We upload sequence data to GenBank and obtain accession number: bank It 2272786 (Seq 1MN 587722).

The strain is named as Helminthosporium rostratum Y9511-X050, and is preserved in Guangdong province microbial culture collection (GDMCC for short) of No. 59 building 5 of No. 100 college of Michelia Tourette, guangzhou, guangdong province in 2019, 10 and 8 days, and the preservation number is GDMCC NO:60804.

Example 4 safety of P.rostratus strain Y9511-X050 on Rice

1. Preparation of spore suspension of Y9511-X050 Strain

Inoculating Y9511-X050 strain into 9cm culture dish containing PDA culture medium, culturing at 28 deg.C for 14 days, washing with 0.5 ‰ (v/v) Tween 80 water solution, filtering with four layers of gauze to remove mycelium to obtain spore suspension, and making spore suspension with concentration of 10 ⁶ spores/mL.

2. Rice for culture test

The rice variety is soft Huayou 6100 (purchased from Guangdong Huanong big seed industry Co., ltd.), and is cultivated in a constant temperature incubator at 28 ℃ until the seed emerges, then the seed emerges, and is transplanted into a pot, 4 rice plants are transplanted in each pot, and the operation is repeated for 4 times, and the seed is placed outdoors for growth.

3. Test method

Spraying the spore suspension liquid on riceSimultaneously, the original strain and the rice which is not sprayed with any bacteria liquid and is only treated by water containing Tween (the concentration of the Tween aqueous solution is 0.5 per thousand (v/v)) are used as controls (the spraying amount is 80mL/m ² ). The treated living rice was cultured in a humidified state for at least 48 hours, and then transferred to a greenhouse for growth, and each treatment was repeated 4 times. And 7d, grading and inspecting the disease occurrence condition, and grading the disease according to different degrees of the treated plant leaf diseases.

Grading different rice disease degrees refers to the grading standard of Chen Yong (2001), and the concrete grading standard of rice diseases is as follows:

level 0: the rice has no diseases and is expressed by NS;

level 1: the rice leaf has lesion spots but not more than 1/2 of the whole leaf, and is expressed by HS;

and 2, stage: the rice died from whole leaves and was denoted by S.

4. And (3) test results:

the safety of strains Y9511 and Y9511-X050 towards rice was determined by the above test, and the test results are shown in Table 10 and FIG. 5, which indicates that neither strain Y9511-X050 nor strain Y9511 invade rice. Experiments show that when the mutant strain Y9511-X050 and the strain Y9511 are applied to paddy fields, the host range is unique.

TABLE 10 safety (indoor) determination of highly pathogenic mutagenized strains on rice

The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such modifications are intended to be included in the scope of the present invention.

Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the protection scope of the present invention, although the present invention is described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions can be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims (10)

1. A strain of mutant Helminthosporium rosthornii (Exserohilum rostratum) Y9511-X050 is characterized in that: the preservation number is GDMCCNO:60804, and the microbial strain preservation center is preserved in No. 59 building of No. 5 building of Michelia Tourette No. 100 college in Guangzhou, guangdong province in 2019, 10 and 8 days.

2. Spores of Helminthosporium umbilicalis Y9511-X050 according to claim 1.

3. The method for preparing spores of Helminthosporium umbilicalis Y9511-X050 according to claim 2, comprising the following steps:

inoculating the mutant hirsutella himurium to a PDA culture medium, culturing at 28-30 ℃, and filtering to remove mycelia to obtain spores of the mutant hirsutella himurium;

the culture time is 14 days;

the filtration is carried out by gauze.

4. Use of spores of Helminthosporium rhynchophyllum mutagenic strain Y9511-X050 according to claim 1 or Helminthosporium rhynchophyllum Y9511-X050 according to claim 2 in preparation of a biological herbicide.

5. Use according to claim 4, characterized in that: the grass is a moleplant weed.

6. Use according to claim 5, characterized in that: the biological control organisms of the biological herbicide are stephania japonica in a paddy field.

7. A biological agent for biological control of Euphorbia lathyris L, characterized in that: the active ingredients are spores of the mutant T.rostratum Y9511-X050 of claim 1 and/or the mutant T.rostratum Y9511-X050 of claim 2.

8. The biological preparation for the biological control of Euphorbia lathyris according to claim 7, characterized in that: the concentration of the spores of the mutant Helminthosporium rosthornii Y9511-X050 in the biological preparation is 10 ⁵ ～10 ⁷ spores/mL.

9. The biological preparation for the biological control of Euphorbia lathyris according to claim 8, characterized in that:

the biological preparation can also contain a carrier acceptable in the aspect of pesticide pharmacy;

the carrier is emulsifier and water;

the emulsifier is Tween 80;

the concentration of the emulsifier in the biological preparation is 0.5 per mill of volume percentage.

10. Use of a new strain of Helminthosporium versicolor Y9511-X050 according to claim 1 or Helminthosporium versicolor Y9511-X050 spores according to claim 2, and/or a biological agent for biological control of Euphorbia lathyris according to any one of claims 7-9 for controlling Euphorbia lathyris.

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