A biocontrol strain for controlling poplar canker and its application

Abstract

This invention relates to the field of biocontrol strains. This invention provides a biocontrol strain for controlling poplar canker and its application; the Latin name of the biocontrol strain is... Bacillus from Velez The strain obtained in this invention, with the accession name BVyx001, is deposited at the China General Microbiological Culture Collection Center (CGMCC) on March 3, 2026, with accession number CGMCC No. 37835. This strain exhibits significant antagonistic activity against both *Botrytis cinerea* and *Cyclocarya paliurus*, demonstrating broad-spectrum and highly effective antibacterial activity. The fermentation broth of the strain shows a sustained and stable inhibitory effect on the pathogens. This strain is derived from natural plant tissues, ensuring high ecological safety and minimizing environmental pollution and pesticide residues, thus reducing the use of chemical pesticides and aligning with the development direction of green prevention and control of forestry diseases.

Description

Technical Field

[0001] This invention relates to the field of biocontrol strain technology, and in particular to a biocontrol strain for controlling poplar canker and its application. Background Technology

[0002] Poplar is an important fast-growing timber species and ecological protection forest species, characterized by rapid growth, strong adaptability, easy propagation, and wide range of timber uses. It plays a vital role in farmland shelterbelts, roadside greening, timber forests, and ecological restoration. However, with the continuous expansion of poplar plantation areas, the high proportion of clonal cultivation, and relatively simple stand structures, poplar diseases are becoming increasingly serious, posing a significant obstacle to the healthy development of the poplar industry. Among these, poplar canker is one of the most severe diseases affecting poplar branches and trunks. It mainly damages branches and trunks, often leading to bark necrosis, branch and trunk cankers, and weakened tree vigor. In severe cases, it can cause the death of young trees or hinder the growth of entire forests, resulting in significant economic losses for poplar plantation management and seedling production.

[0003] The pathogens of poplar canker are quite complex, with trunk canker caused by *Botrytis cinerea* and rot caused by *Heterocystis aurea* being particularly damaging. The pathogens typically invade the host through wounds, lenticels, or weak tissues, and spread rapidly under suitable temperature and humidity conditions, causing bark discoloration, depressions, cracking, gumming, or the formation of vesicular lesions. Because these diseases primarily occur in the branch and trunk tissues, the pathogens have a strong latent infectivity ability, and the disease incidence is closely related to seedling quality, environmental stress, mechanical damage, and stand management levels, control is quite challenging.

[0004] Currently, the control of poplar canker mainly relies on measures such as strengthening cultivation management, selecting disease-resistant varieties, removing diseased plant debris, reducing wounds, and chemical control. While these measures can reduce the incidence of the disease to some extent, they still have significant shortcomings. On the one hand, the selection cycle for disease-resistant varieties is long, and the pathogen population composition in different regions is complex, making resistance easily affected by the environment. On the other hand, chemical control suffers from problems such as frequent application, unstable efficacy, limited duration of action, and the risk of environmental pollution and pathogen resistance, making it difficult to meet the needs of green, ecological, and sustainable forestry development. Therefore, developing safe, efficient, and environmentally friendly new technologies for the control of poplar canker is of great significance.

[0005] Biological control is an important green approach to disease prevention and control, utilizing beneficial microorganisms or their metabolites to inhibit the growth of pathogens and prevent the occurrence and spread of diseases. In recent years, biocontrol microorganisms such as Bacillus, Pseudomonas, and Trichoderma have received widespread attention in plant disease control due to their advantages, including rapid reproduction, strong adaptability, good colonization ability, production of various antimicrobial active substances, and induction of plant resistance. Among them, Bacillus biocontrol bacteria can form highly resistant spores, facilitating production, processing, storage, and field application, and possessing good potential for industrial development. These strains exert their disease control effects through multiple mechanisms, including nutrient and space competition, secretion of antimicrobial proteins or lipopeptides, production of volatile antimicrobial substances, promotion of plant growth, and induction of systemic resistance in the host. Summary of the Invention

[0006] The purpose of this invention is to provide a biocontrol strain for the prevention and control of poplar canker and its application, providing a theoretical basis and technical support for the development of efficient and stable biocontrol agents for poplar canker.

[0007] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a biocontrol strain for controlling poplar canker, the Latin name of which is... Bacillus velezensis The accession name is BVyx001, the accession location is China General Microbiological Culture Collection Center (CGMCC), the accession date is March 3, 2026, and the accession number is CGMCC No. 37835.

[0008] The present invention also provides the application of the biocontrol strains described herein in inhibiting Staphylococcus aureus and / or Cyclosporium aureum.

[0009] The present invention also provides the application of the aforementioned biocontrol strain in the control of poplar canker.

[0010] The present invention also provides the application of the aforementioned biocontrol strain in the control of poplar canker.

[0011] This invention provides a biocontrol strain for controlling poplar canker and its application. The Latin name of the biocontrol strain is... Bacillus velezensis The Bacillus belyceae BVyx001 was deposited at the China General Microbiological Culture Collection Center (CGMCC) on March 3, 2026, with accession number CGMCC No. 37835. This invention screened and obtained Bacillus belyceae BVyx001, which is effective against the poplar canker pathogen Staphylococcus aureus (…). Botryosphaeria dothidea ) and the poplar rot pathogen, *Aureobasidium aureum* ( Cytospora chrysospermaBoth exhibit significant antagonistic effects, with inhibition rates reaching 56.86% and 78.05%, respectively, demonstrating broad-spectrum and highly efficient antibacterial activity. The fermentation broth of this invention strain shows a sustained and stable inhibitory effect on the pathogen, with the PDB fermentation broth achieving a 100% inhibition rate on pathogen mycelial growth, indicating that this strain can produce highly efficient and stable antibacterial active substances and has good development potential. This invention strain can significantly inhibit the expansion of poplar canker lesions, achieving control effects of 46.20% and 31.87% against Populus tomentosa 107 and Populus tomentosa var. mongolica, respectively, indicating good colonization and disease prevention capabilities within the plant, effectively reducing disease occurrence. This invention strain is derived from natural plant tissue, has high ecological safety, and is unlikely to cause environmental pollution or pesticide residues, reducing the use of chemical pesticides and aligning with the development direction of green prevention and control of forestry diseases. Attached Figure Description

[0012] Figure 1 The study aimed to determine the antagonistic activity of four bacterial strains against two poplar pathogens. Figure 2 The plate inhibition effect of aseptic fermentation broth of biocontrol bacterium BVyx001 on two poplar pathogens was studied. Figure 3 The efficacy of biocontrol agent BVyx001 against canker of Populus tomentosa 107 and Populus tomentosa in potted seedlings under greenhouse conditions was investigated.

[0013] Preservation Instructions

[0014] Bacillus velezensis BVyx001, with the deposit name BVyx001 and the taxonomic name Bacillus velezensis, is deposited at the China General Microbiological Culture Collection Center (CGMCC) on March 3, 2026, with the accession number CGMCC No. 37835. The deposit address is Institute of Microbiology, Chinese Academy of Sciences, No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing. Detailed Implementation

[0015] This invention provides a biocontrol strain for controlling poplar canker, the Latin name of which is... Bacillus velezensis The accession name is BVyx001, the accession location is China General Microbiological Culture Collection Center (CGMCC), the accession date is March 3, 2026, and the accession number is CGMCC No. 37835.

[0016] The present invention also provides the application of the biocontrol strains described herein in inhibiting Staphylococcus aureus and / or Cyclosporium aureum.

[0017] The present invention also provides the application of the aforementioned biocontrol strain in the control of poplar canker.

[0018] The present invention also provides the application of the aforementioned biocontrol strain in the control of poplar canker.

[0019] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0020] Example 1: Test strain and culture conditions

[0021] The bacterial strain used in the experiment, BVyx001, was isolated from the needles of Pinus tabuliformis in Aohan Banner, Chifeng City, Inner Mongolia Autonomous Region, and placed in NA or NB medium at a culture temperature of 28℃.

[0022] Two poplar pathogenic fungi tested, *Staphylococcus aureus* (the pathogen of poplar canker) and *Staphylococcus aureus* (the pathogen of poplar rot), were placed in PDA medium and incubated at 28°C. Strain BVyx001 is deposited at the China General Microbiological Culture Collection Center.

[0023] Example 2: Inhibitory effect of strain BVyx001 on the mycelial growth of two poplar pathogenic fungi.

[0024] The antagonistic ability of bacterial strain BVyx001 against two poplar pathogenic fungi was determined using a confrontation culture method. The bacterial strain was inoculated onto NA medium and incubated at 28°C for 2 days. The fungal strain was incubated on PDA plates at 25°C for 5 days. A 6 mm diameter mycelial disc was then taken using a punch and placed in the center of a new 90 mm PDA plate. 6 μL of overnight cultured BVyx001 bacterial suspension was inoculated at a distance of 2.25 cm from the mycelial disc in four directions (top, bottom, left, and right). Blank NA medium was used as a control. Each treatment was repeated three times. After incubation at 25°C for 4 days, colony size was measured and the inhibition rate was calculated: y = (AB) / A × 100 (y: inhibition rate (%), A: diameter of pathogenic fungal colony in the control plate, B: diameter of pathogenic fungal colony in the treatment group). The bacterial strain with the best antifungal effect was selected as a biocontrol strain for poplar canker and rot.

[0025] The selected biocontrol strains were inoculated into PDB and NB media and cultured in a shaker at 28°C and 180 r / min for 2 days. OD 600 =2.0, the culture was centrifuged at 8000 r / min for 20 min at 4℃, and the supernatant was collected; after sterilization by filtration through a 0.22 μm filter membrane, it was mixed with molten PDA medium at 50℃ instead of H2O. A 6 mm diameter pathogenic bacterial cake was placed in the center of a PDA plate containing the bacterial filtrate. Using blank PDA as a control, all plates were incubated at 25℃ for 5 days and 12 days, with each treatment having three replicates. The inhibition rate was calculated as above.

[0026] result: The effect of bacterial strain BVyx001 on the mycelial growth of poplar pathogens is as follows: Figure 1 As shown.

[0027] Plate confrontation experiments using bacteria BVyx001 and its suspension against the pathogens of poplar canker and rot showed that BVyx001 had a significant antagonistic effect on the two poplar pathogens.

[0028] The bacterial BVyx001 showed an inhibition rate of 56.86% against the growth of *Botrytis cinerea* hyphae and 78.05% against *Cyclocarya paliurus*. The inhibition band width of BVyx001 against both pathogens was over 7.5 mm.

[0029] Example 3: Biocontrol activity of biocontrol strain BVyx001 against *Botrytis cinerea* inoculation on poplar trees.

[0030] One-year-old healthy black poplar and white poplar were selected. A 6mm scalded wound was made in the bark of the main trunk near the 7th bud from the top. A 6mm scalded wound of *Botrytis cinerea* pathogen was inoculated. Ten days after inoculation, the aseptic fermentation broth of strain BVyx001 (OD2000) was sprayed on the wound. 600 =2.0 (diluted 10 times), with the water spraying group as the control, and 3 replicates per treatment. The samples were incubated at 25℃ and 85% humidity for 10 days, and the lesion length was measured to calculate the control effect: Control effect = (lesion length in CK group - lesion length in treatment group) / lesion length in CK group × 100%.

[0031] result: The plate inhibition effect of aseptic fermentation broth of biocontrol bacteria BVyx001 on poplar pathogens is as follows: Figure 2 As shown The plate inhibition test results of the BVyx001 aseptic fermentation broth showed that the antibacterial effect of the PDB medium fermentation broth against both pathogens was close to 100% at both 4 and 12 days of culture, while the antibacterial effect of the NB medium fermentation broth against Staphylococcus aureus decreased to 29.23% at 12 days. Therefore, the PDB fermentation broth had the best antibacterial effect.

[0032] The aseptic fermentation broth of biocontrol bacteria BVyx001 has the following effect on the prevention of poplar canker in potted seedlings: Figure 3 As shown.

[0033] The experimental results showed that treatment with BVyx001 bacterial solution significantly inhibited the expansion of canker lesions in Populus tomentosa 107 and Populus tomentosa (T<0.01), with inhibition effects of 46.2% and 31.87%, respectively.

[0034] As can be seen from the above embodiments, the present invention provides a biocontrol strain for controlling poplar canker and its application. The Latin name of the biocontrol strain is... Bacillus velezensisThe Bacillus belyceae BVyx001 was deposited at the China General Microbiological Culture Collection Center (CGMCC) on March 3, 2026, with accession number CGMCC No. 37835. This invention screened and obtained Bacillus belyceae BVyx001, which is effective against the poplar canker pathogen Staphylococcus aureus (…). Botryosphaeria dothidea ) and the poplar rot pathogen, *Aureobasidium aureum* ( Cytospora chrysosperma Both exhibit significant antagonistic effects, with inhibition rates reaching 56.86% and 78.05%, respectively, demonstrating broad-spectrum and highly efficient antibacterial activity. The fermentation broth of this invention strain shows a sustained and stable inhibitory effect on the pathogen, with the PDB fermentation broth achieving a 100% inhibition rate on pathogen mycelial growth, indicating that this strain can produce highly efficient and stable antibacterial active substances and has good development potential. This invention strain can significantly inhibit the expansion of poplar canker lesions, achieving control effects of 46.20% and 31.87% against Populus tomentosa 107 and Populus tomentosa var. mongolica, respectively, indicating good colonization and disease prevention capabilities within the plant, effectively reducing disease occurrence. This invention strain is derived from natural plant tissue, has high ecological safety, and is unlikely to cause environmental pollution or pesticide residues, reducing the use of chemical pesticides and aligning with the development direction of green prevention and control of forestry diseases.

[0035] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A biocontrol bacterial strain for controlling poplar canker, characterized in that, The Latin name of the biocontrol strain is Bacillus velezensis , the deposit name is BVyx001, the deposit place is China General Microbiological Culture Collection Center, the deposit date is March 3, 2026, and the deposit number is CGMCC No. 37835.

2. The use of the biocontrol strain of claim 1 in inhibiting Botryosphaeria dothidea and / or Guignardia bidwellii.

3. The use of the biocontrol strain of claim 1 in preventing poplar canker.

4. The use of the biocontrol strain of claim 1 in preventing poplar dieback.

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