Alkali-resistant marine bacillus GS3 and application thereof

Abstract

The invention discloses an alkali-resistant marine bacterium (Pelagandopus alkalilerans) GS3, and the preservation number of the alkali-resistant marine bacterium is CGMCC (China General Microbiological Culture Collection Center) NO: 23985. The GS3 can inhibit various plant bacterial diseases, fungal diseases and plant virus diseases. The alkali-resistant marine bacillus GS3 can be used for preparing microbial pesticides or microbial fertilizers for preventing and controlling plant diseases, meets the national green prevention and control development requirements, reduces the pollution of chemical pesticides to soil, water sources and environments, and avoids or slows down the drug resistance of plant pathogens. The strain has a wide application prospect in the aspects of biological pesticides, biological fertilizers and seed treatment.

Description

Technical Field

[0001] The invention belongs to the technical field of biological control, and specifically relates to an alkali-resistant marine bacillus GS3 and an application thereof. Background Art

[0002] Plant diseases are abnormal plant conditions caused by infection by pathogenic microorganisms (such as fungi, bacteria, viruses, nematodes, etc.) or environmental stress, and their harm is extensive and far-reaching. Plant diseases can easily hinder plant growth and development, leading to reduced yields, poor quality, and even death. Globally, crop losses due to plant diseases are about 10%-30% each year, threatening food safety. Some diseases cannot be cured once they are infected. For example, citrus Huanglongbing (bacterial disease) is the "cancer" of the global citrus industry and there is no cure. The large-scale occurrence of diseases has led to increased prevention and control costs, and pesticide investment, research and development of disease-resistant varieties, and disease monitoring consume a lot of resources, and excessive use of drugs may cause ecological pollution. Using eco-friendly measures (such as biological control) to reduce disease risks is an important issue in modern agriculture and ecological protection.

[0003] The biological control method of plant diseases is to use the growth-promoting and pathogen-antagonistic properties of beneficial microorganisms to prevent and control diseases while promoting plant growth. In recent years, biological control has gradually become a hot topic in disease control due to its green and sustainable characteristics. Therefore, screening out biological resources that have antagonistic effects on pathogens is a task of great significance. At present, biocontrol bacteria have problems such as poor colonization ability under natural conditions, weak drug resistance, and unstable control effects in plant disease control. Therefore, further screening of microbial strains with excellent performance and good stability for the prevention and control of plant diseases is the current research focus in this field. Summary of the invention

[0004] The purpose of the present invention is to provide an alkali-resistant marine bacillus (Pelagirhabdus alkalitolerans) GS3 and application thereof in preventing and controlling plant diseases.

[0005] The present invention provides a strain of alkali-resistant marine bacillus (Pelagirhabdus alkalitolerans) GS3, which was deposited in the General Microbiology Center of China Microorganism Culture Collection Administration on November 26, 2021, with the deposit number CGMCC NO: 23985. The deposit address is No. 3, Yard No. 1, Beichen West Road, Chaoyang District, Beijing, Institute of Microbiology, Chinese Academy of Sciences.

[0006] The invention discloses an alkali-resistant marine bacillus (Pelagirhabdus alkalitolerans) GS3, whose deposit number is CGMCCNO:23985.

[0007] The invention discloses an application of the alkali-resistant marine bacillus (Pelagirhabdus alkalitolerans) GS3 in preventing and controlling bacterial diseases of plants.

[0008] The plant bacterial diseases are citrus Huanglongbing, citrus canker, amylopectin, tobacco bacterial wilt or melon bacterial fruit spot.

[0009] The invention discloses an application of the alkali-resistant marine bacillus (Pelagirhabdus alkalitolerans) GS3 in preventing and controlling plant fungal diseases.

[0010] The plant fungal diseases are wheat fusarium head blight, rice blast, apple tree rot, apple anthracnose leaf blight, grape gray mold, grape canker, tobacco black shank, tobacco brown spot or strawberry powdery mildew.

[0011] The invention discloses an application of the alkali-resistant marine bacillus (Pelagirhabdus alkalitolerans) GS3 in preventing and controlling plant viral diseases.

[0012] The plant virus disease is tobacco mosaic virus, tomato virus disease or grape fanleaf virus disease.

[0013] A method for preventing and controlling plant diseases, comprising: introducing Pelagirhabdus alkalitolerans GS3 at a concentration of 1.0×10 7 ~1.5×10 8 cfu / mL fermented bacterial solution spray or root irrigation treatment.

[0014] A biological preparation comprising a fermentation product or a metabolite of the GS3 strain of Pelagirhabdus alkalitolerans.

[0015] The dosage form of the biological preparation includes water suspension, water, microemulsion, powder, wettable powder, freeze-dried powder, granule or water dispersible granule.

[0016] The beneficial effects of the present invention are as follows: the alkali-resistant marine bacillus GS3 of the present invention has inhibitory activity against plant pathogens, simple culture conditions, fast propagation speed, easy storage and transportation, strong stress resistance, and easy colonization in soil and plants. The alkali-resistant marine bacillus GS3 of the present invention is obtained by separation and purification from Suaeda salsa, and is safe, non-toxic and environmentally friendly. After application, it can improve the soil microenvironment, reduce the amount of chemical pesticides used, protect the ecological environment, increase crop yield and quality, and has good social, economic and ecological benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is the colony morphology of alkali-resistant marine bacillus GS3.

[0018] Figure 2 This is the plate inhibitory effect of strain GS3 on plant pathogenic fungi.

[0019] Figure 3 This is the plate inhibition effect of strain GS3 on plant pathogenic bacteria. DETAILED DESCRIPTION

[0020] In order to facilitate the understanding of the present invention, the present invention will be described more fully below. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0021] Example 1 Isolation and identification of strains

[0022] Grind the Suaeda salsa plants, and separate and purify them from the water dilution of the ground samples by dilution and plating. Weigh 1g of Suaeda salsa ground material, add it to 10ml of sterile water, and culture it at 180rpm for 30min, then dilute it with water, and the dilution gradient is 10×, 100× and 1000×. Take 100μl of the dilution of each gradient and spread it on LB medium, culture it at 28℃ for 1d, pick a single colony and purify it by streaking on the LB medium plate. The purified single colony is transferred to a new LB medium and stored for later use.

[0023] The plate confrontation antagonism test was used to screen highly active antagonistic strains, and it was found that GS3 showed high antagonistic activity against plant pathogenic fungi and bacteria. Figure 1 ), physiological and biochemical indices, 16S and gyrA gene sequence determination, etc., GS3 was identified as Pelagirhabdus alkalitolerans.

[0024] Example 2 Determination of the antibacterial activity of alkali-resistant marine bacillus GS3 against plant pathogenic fungi

[0025] The plate confrontation method was used to determine the inhibitory activity of GS3 strain against plant pathogenic fungi. The target plant pathogenic strains were: Fusarium graminearum, Magnaporthe oryzae, Valsa mali, Colletotrichum acutatum, Botrytis cinerea, Botryosphaeria dothidea, Alternaria alternata, and Phytophthora parasitica. The specific operation was as follows: the target plant pathogens were cultured at 28°C for about 5 days, the hyphae at the edge of the colony were scraped, and the hyphae balls were about 2 mm in diameter, which were inoculated in the center of the PDA medium plate, and then the cultured GS3 culture solution was adjusted to OD 600 At about 1, 1 μl was dripped on the side of the mycelium ball about 2.5 cm away, and cultured at 28°C for 4 days to observe the inhibitory effect of bacteria on the growth of target strains. The radius away from and close to the GS3 colony was measured as the radius of the control and treated fungi, and the inhibition rate of GS3 strains on plant pathogenic fungi was calculated ( Figure 2 ). Inhibition rate (%) = (colony radius of control group - colony radius of treatment group) / colony radius of control group × 100%.

[0026] The results of the antibacterial spectrum test showed that the GS3 strain effectively inhibited the growth of the mycelium of the tested pathogenic fungi, with an inhibition rate of 62.50-84.09% (Table 1), among which the inhibition rate of apple tree rot pathogen was the highest. GS3 had a strong inhibitory effect on the mycelium growth of the above 8 tested pathogens, and the mycelium at the edge of the colony of the 8 pathogenic fungi cultured against the GS3 strain grew sparsely or stopped growing.

[0027] Table 1 Inhibitory effect of alkali-resistant marine bacillus GS3 on various pathogenic fungi

[0028]

[0029]

[0030] Example 3 Antagonistic effect of alkali-resistant marine bacillus GS3 on plant pathogenic bacteria

[0031] The strain GS3 was cultured against bacterial pathogens, including Ralstonia solanacearum, Agrobacterium tumefaciens, Erwinia amylovora, Xanthomonas citri and Acidovora x citrulli, and its antibacterial effect was observed after culturing at 28°C overnight. Figure 3 The test results showed that strain GS3 had antagonistic effects on these five pathogenic bacteria, with the diameter of the inhibition zone ranging from 12 to 20 mm (Table 2).

[0032] Table 2 Inhibitory effect of alkali-resistant marine bacillus GS3 on various pathogenic bacteria

[0033]

[0034] Example 4 In vitro protective effect of alkali-resistant marine bacillus GS3 against apple anthracnose

[0035] Apple anthracnose was inoculated on a PDA plate and cultured at 28°C for 10 days. Mycelium and spores on the surface of the culture medium were scraped into a centrifuge tube, sterile water was added and vortexed for 1 min, and the spore solution was filtered with lens paper to adjust the concentration of spore solution to 10 5 The alkali-resistant marine bacillus GS3 was inoculated into LB liquid culture medium and cultured in a shaking incubator at 200 rpm and 30°C for 6 days. The fermentation liquid concentration reached 10 9 cfu / mL. Cut the newly unfolded leaves of the Golden Crown apple tree, dilute the fermentation liquid 500 times and spray it, use clean water as the control, and treat 10 leaves for each treatment. After 8 hours, spray and inoculate the apple anthracnose spore suspension, keep the leaves moist and culture for 5 days to observe the disease situation of the leaves. The grading method and calculation formula are as follows:

[0036] The grading method is based on the percentage of the lesion area on each leaf to the entire leaf area;

[0037] Level 0: no disease;

[0038] Level 1: The lesion area accounts for less than 5% of the entire leaf area;

[0039] Level 3: The lesion area accounts for 6-15% of the entire leaf area;

[0040] Level 5: The lesion area accounts for 16-25% of the entire leaf area;

[0041] Level 7: The lesion area accounts for 26-50% of the entire leaf area;

[0042] Level 9: The lesion area accounts for more than 51% of the entire leaf area.

[0043] Disease index = 100 × ∑ (number of diseased leaves at each level × relative level value) / (total number of leaves surveyed × 9).

[0044] In the in vitro inoculation test, the control had severe disease, with large and continuous lesions, while the leaves treated with 500-fold dilution of the fermentation liquid of strain GS3 had mild disease and smaller lesions. The 500-fold dilution of the fermentation liquid of strain GS3 had a protective effect of 74.29% against apple anthracnose, which had a significant protective effect.

[0045] Example 5: Control effect of alkali-resistant marine bacillus GS3 on strawberry powdery mildew

[0046] Test method: Spray inoculation with spore suspension. Select uniform 6-leaf-old potted strawberry seedlings, dilute the 6-day-old GS3 bacterial solution 100, 200, and 500 times for spray treatment, with 4 replicates per treatment and 4 pots per replicate. Spraying with clean water was used as a control. After 24 hours, take the strawberry leaves covered with powdery mildew, gently rinse the fresh spores on the back of the leaves with sterile water, filter with double-layer lens paper, make a spore suspension, and spray inoculate. The inoculated strawberry plants were moved to a 23°C greenhouse, and the control leaves treated with clean water were fully diseased for graded disease investigation, and the disease index was used to calculate the prevention effect.

[0047] The classification method and calculation formula are as follows: The classification method refers to Example 4;

[0048] Disease index = 100 × ∑ (number of diseased leaves at each level × relative level value) / (total number of leaves investigated × 9);

[0049] Control effect (%) = 100 × (control disease index - treatment disease index) / control disease index.

[0050] In the strawberry powdery mildew pot test, different dilution multiples of the alkali-resistant Marine Bacillus GS3 fermentation liquid can inhibit the occurrence of strawberry powdery mildew, among which the prevention effect of 100 times liquid was as high as 92.76%, the 200 times liquid was slightly lower than the 100 times liquid, and the 500 times liquid was slightly lower. It is recommended to use the alkali-resistant Marine Bacillus GS3 fermentation liquid at a multiple of 100-500 times.

[0051] Table 3 The control effect of alkali-resistant marine bacillus GS3 on powdery mildew of potted strawberry

[0052] deal with Disease index (%) Control effect (%) GS3 fermentation liquid 100 times 6.04 92.76 GS3 fermentation liquid 200 times 7.62 90.87 GS3 fermentation liquid 500 times 10.25 87.72 Clear water control 83.46

[0053] Example 6: The efficacy of alkali-resistant marine bacillus GS3 in preventing citrus Huanglongbing

[0054] Potted control effect of alkali-resistant marine bacillus GS3 on citrus Huanglongbing: The potted citrus variety is Ehime 38. The positive plants are determined by conventional PCR testing, and the citrus plants with milder disease are marked for subsequent pesticide application tests, sample collection and appearance grading investigations. GS3 fermentation liquid is applied twice by foliar spraying and root irrigation, and the disease situation is investigated one month after the last foliar spraying.

[0055] Citrus Huanglongbing empirical grading standard: Based on experience, the disease is divided into 6 levels. Level 0: The whole tree is disease-free; Level 1: 1 to 2 branches on the tree have mottled yellow leaves; Level 2: Some side branches or main branches have mottled yellow symptoms, and the symptomatic branches account for less than 1 / 3 of the whole tree; Level 3: The symptomatic side branches or main branches account for more than 1 / 3 and less than 2 / 3 of the whole tree; Level 4: The symptomatic branches are more than 2 / 3; Level 5: The whole tree is dead.

[0056] Table 4 Potted plant control effect of alkali-resistant marine bacillus GS3 on citrus Huanglongbing

[0057] deal with Disease index (%) Control effect (%) GS3 fermentation liquid 100 times 12.61 82.63 GS3 fermentation liquid 200 times 18.52 74.49 GS3 fermentation liquid 500 times 30.49 58.01 Clear water control 72.61

[0058] Field efficacy of alkali-resistant marine bacillus GS3 against citrus Huanglongbing: Starting from March 5, 2024, citrus trees were treated with alkali-resistant marine bacillus GS3 fermentation liquid, the variety was Ehime 38, once a month until September 2024, a total of 7 times. GS3 fermentation liquid was diluted and 5L of bacterial liquid was applied to each tree each time. Citrus leaves were extracted on March 1, 2024 and October 10, 2024 for Huanglongbing bacteria content detection.

[0059] The detection of Huanglongbing bacteria content mainly includes sample processing, DNA extraction, real-time fluorescence quantitative PCR (qPCR) detection and result calculation, as follows:

[0060] 1. Sample processing: Take 6 citrus leaves, wash them with clean water and dry them, and weigh 0.1 g of leaf midrib tissue as the material for subsequent DNA extraction.

[0061] 2. DNA extraction: DNA from leaf midribs was extracted using the CTAB method.

[0062] 3. Real-time fluorescence quantitative PCR (qPCR) detection: The primers used were CQULA04F / CQULA04R, synthesized by Sangon Biotech (Shanghai) Co., Ltd.; TB Green Premix Ex TaqⅡ was purchased from TaKaRa. Reaction system: TBGreen Premix Ex TaqⅡ12.5μL, primers CQULA04F / CQULA04R 0.8μL (10μmol / L), deionized water 5.9μL, DNA solution 5μL (about 100ng), total volume 25μL. Amplification program: 95℃ pre-denaturation for 1min; 95℃ denaturation for 15s, 59℃ annealing for 15s, 72℃ extension for 45s, for a total of 45 cycles. Each DNA sample was repeated 3 times.

[0063] 4. Result calculation: By making a standard curve, we get the regression equation Y = (33.95-X) / 3.31, (X is the CT value after qPCR reaction, Y is the Lg value of DNA template solution), the DNA of DNA template solution comes from m (leaf midrib mass, g) and is dissolved in 100 μL sterile water, then the content of Huanglongbing bacteria = (10 Y ×100) / m.

[0064] Pathogen reduction rate (%) = [(pathogen content before treatment - pathogen content after treatment) / pathogen content before treatment] × 100

[0065] Corrected protective effect (%) = [(reduction rate of pathogens in the treatment group - reduction rate in the blank control group) / (1 - reduction rate in the blank control group)] × 100.

[0066] The results of the Huanglongbing bacteria content detection are shown in Table 5. The reduction rate of the bacteria content in citrus trees treated with GS3 fermentation liquid is higher than that in the control treatment, and the corrected prevention efficiency is 75.97-84.32%, which has a significant therapeutic effect on citrus Huanglongbing.

[0067] Table 5 Comparison of citrus Huanglongbing pathogen content before and after treatment

[0068]

[0069] Example 7 Inhibitory effect of alkali-resistant marine bacillus GS3 on tobacco mosaic virus (TMV)

[0070] The strain of alkali-resistant marine bacillus GS3 was fermented to obtain bacterial liquid. The half-leaf method was used to determine the inhibition rate of GS3 on TMV infection by using the allergic necrosis reaction of Nicotiana benthamiana to TMV. The young leaves of TMV virus source with full disease were ground and filtered with distilled water at a ratio of 1:10 (mass to volume) and used as virus test samples. The virus test sample was mixed with equal volumes of liquid LB culture medium, and rubbed on the left half of Nicotiana benthamiana after 10 minutes as a control. The GS3 dilution was mixed with equal volumes of the virus sample, and rubbed and inoculated on the right half of Nicotiana benthamiana after 10 minutes as a treatment group; in addition, the Ningnanmycin treatment group was used as a positive control. After the necrosis spots appeared, the number of necrosis spots on the left and right half leaves was recorded respectively. Three replicates were performed, and three leaves were inoculated for each tobacco plant. Inhibition rate (%) = [(number of control necrosis spots - number of treatment necrosis spots) / number of control necrosis spots] × 100%. The results are shown in Table 6. Evaluated by the average inhibition rate, strain GS3 has a better antagonistic effect on TMV. Three repeated experiments showed that the inhibition rate of the fermentation broth of strain GS3 on TMV can reach 75.76%, while the average inhibition rate of Ningnanmycin is only 65.71%. The alkali-resistant marine bacillus GS3 screened by the present invention has a significantly higher inhibitory effect on TMV than the chemical pesticide Ningnanmycin.

[0071] Table 6 Inhibition rate of alkali-resistant marine bacillus GS3 on tobacco mosaic virus

[0072] deal with Number of dead spots (left control) Number of dead spots (right treatment) Control effect (%) GS3 fermentation liquid 100 times 33 8 75.76 GS3 fermentation liquid 200 times 40 11 72.50 GS3 fermentation liquid 500 times 28 7 75.00 8% Ningnanmycin 800 times dilution 35 12 65.71

[0073] Example 8 Field efficacy test of alkali-resistant marine bacillus GS3 fermentation liquid against tomato virus disease

[0074] The experiment was arranged in a tomato greenhouse in Xingcheng City, Liaoning Province. The experimental crop was tomato, and the variety was Jingcai No. 8. The target of prevention and control: tomato virus disease. Method for preparing the virus for inoculation: collect fresh tomato leaves infected with tomato virus disease, add buffer (phosphate buffered saline (PBS), pH = 7) according to the ratio of fresh diseased leaves: buffer = 1:3 (g:ml). Put the above mixture into a sterilized mortar, add a certain amount of quartz sand, grind into a homogenate, filter with sterile gauze, and inoculate the virus by friction inoculation.

[0075] Field prevention test: When the first true leaf (broken heart) appears on the tomato seedlings, spray the fermentation liquid of strain GS3. Spray 40 tomato seedlings for each treatment, and then spray once every 7 days for 3 times. Each treatment is repeated 4 times and randomly arranged. After the spraying of the agent, inoculate the virus. Investigate the disease 10 days after inoculation, calculate the disease index and prevention effect. When investigating tomato virus disease, it is required to investigate all plants in the plot and record the disease situation in a graded manner. Level 0: No symptoms; Level 1: Clear veins of the heart leaf, or slight mosaic; Level 3: Mosaic of the heart leaf and the middle leaves, sometimes necrotic spots appear on the leaves; Level 5: Most leaves are mosaic, a few leaves are deformed and wrinkled, sometimes necrotic spots appear on the leaves or stems, or short stripes appear on the stems; Level 7: Severe mosaic, most leaves are deformed and slender, or the stems and veins have systemic necrosis, and the plants are dwarfed; Level 9: The plants have severe systemic mosaic, deformity, or sometimes severe systemic necrosis, the plants are severely dwarfed, or even die. According to the disease investigation and disease classification, the disease index of each treatment was calculated, and then the control effect was calculated. The results are shown in Table 7. The control effect reached 75.93-90.72%. There was no phytotoxicity to tomatoes when used during the tomato growth period.

[0076] Table 7 Field efficacy test results of alkali-resistant marine bacillus GS3 fermentation liquid for preventing and controlling tomato virus disease

[0077] deal with Disease index (%) Control effect (%) GS3 fermentation liquid 100 times 6.05 90.72 GS3 fermentation liquid 200 times 7.61 88.33 GS3 fermentation liquid 500 times 15.70 75.93 Clear water control 65.22

[0078] Example 9 Experiment on the prevention and treatment of grape fan leaf virus disease by fermentation liquid of alkali-resistant marine bacillus GS3

[0079] Fresh grape leaves infected with Grapevine Fanleaf Virus (GFLV) were collected and the virus for inoculation was prepared in the same manner as in Example 8.

[0080] Virus prevention test of grape pot seedlings: The test was conducted at the experimental base of the Fruit Research Institute of the Chinese Academy of Agricultural Sciences. The grape pot seedling variety was 'Giant Rose 2'. When the grape seedlings had 6-8 leaves, the fermentation liquid of the strain GS3 was sprayed. Ten grape seedlings were sprayed for each treatment, and then sprayed once every 7 days for 3 times. Each treatment was repeated 4 times and randomly arranged. Six days after the first spraying, the virus was inoculated. Ten days after the third spraying of the fungus, the grape leaves of different treatments were collected, and the total RNA was extracted. The real-time fluorescence quantitative RT-PCR method with FL-HP1-F / R as primers was used to detect GFLV. The number of positive leaves in different treatments was counted, and the GFLV detection rate was calculated. The results are shown in Table 8. The virus detection rate of the control was 62.70%, and the detection rate of the GS3 fermentation liquid treatment was 7.39-14.53%, among which the positive detection rate of the 100-fold liquid was the lowest, indicating that the GS3 fermentation liquid had a good preventive effect on grape fan leaf virus disease.

[0081] Table 8 Field efficacy test results of alkali-resistant marine bacillus GS3 fermentation liquid for preventing and controlling grape fan leaf virus disease

[0082] deal with Detection rate of grape fan leaf virus (%) GS3 fermentation liquid 100 times 7.39 GS3 fermentation liquid 200 times 8.25 GS3 fermentation liquid 500 times 14.53 Clear water control 62.70

[0083] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. An alkali-resistant marine bacillus (Pelagirhabdus alkalitolerans) GS3, characterized in that Its deposit number is CGMCC NO:23985.

2. Use of the alkali-resistant marine bacillus (Pelagirhabdus alkalitolerans) GS3 according to claim 1 in preventing and controlling plant bacterial diseases.

3. The use of Pelagirhabdus alkalitolerans GS3 in preventing and treating plant bacterial diseases according to claim 2, characterized in that: The plant bacterial diseases are citrus Huanglongbing, citrus canker, amylopectin, tobacco bacterial wilt or melon bacterial fruit spot.

4. Use of the alkali-resistant marine bacillus (Pelagirhabdus alkalitolerans) GS3 according to claim 1 in preventing and controlling plant fungal diseases.

5. The use of Pelagirhabdus alkalitolerans GS3 in preventing and controlling plant fungal diseases according to claim 4, characterized in that: The plant fungal diseases are wheat fusarium head blight, rice blast, apple tree rot, apple anthracnose leaf blight, grape gray mold, grape canker, tobacco black shank, tobacco brown spot or strawberry powdery mildew.

6. Use of the alkali-resistant marine bacillus (Pelagirhabdus alkalitolerans) GS3 according to claim 1 in preventing and controlling plant viral diseases.

7. The use of Pelagirhabdus alkalitolerans GS3 in preventing and controlling plant viral diseases according to claim 6, characterized in that: The plant virus disease is tobacco mosaic virus, tomato virus disease or grape fanleaf virus disease.

8. A method for preventing and controlling plant diseases, characterized in that: Pelagirhabdus alkali-resistant marine bacillus GS3 was added to the 7 ~1.5×10 8 cfu / mL fermented bacterial solution spray or root irrigation treatment.

9. A biological agent, characterized in that: A fermentation product or metabolite comprising the alkali-resistant marine bacillus (Pelagirhabdus alkalitolerans) GS3 strain according to claim 1.

10. The biological agent according to claim 9, characterized in that The dosage form of the biological preparation includes water suspension, water, microemulsion, powder, wettable powder, freeze-dried powder, granule or water dispersible granule.

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