A Pseudomonas synbiotic for preventing and controlling potato soil-borne bacterial wilt and its application

Abstract

The present invention discloses a Pseudomonas strain PSE7, which is taxonomically named Pseudomonas mohnii, and was deposited at the General Microbiological Center of the China Committee for Culture Collection of Microorganisms on July 28, 2023, with the deposit number of CGMCC No. 28053. The present invention also discloses a Pseudomonas synbiotic for controlling potato soil-borne bacterial wilt, which is composed of Pseudomonas strain PSE7 and one selected from N-acetyl-L-tyrosine or troxerutin. Both N-acetyl-L-tyrosine and troxerutin can promote the inhibitory ability of Pseudomonas PSE7 against Ralstonia solanacearum. When N-acetyl-L-tyrosine is used in combination with Pseudomonas PSE7 and applied to the soil by the root irrigation method, it can significantly reduce the disease index of potato soil-borne bacterial wilt and reduce the incidence of potato bacterial wilt.

Description

Technical Field

[0001] The present invention belongs to the field of microorganisms, and relates to Pseudomonas strain PSE7 and the application of Pseudomonas strain PSE7 in preventing and controlling bacterial wilt, a Pseudomonas synbiotic for preventing and controlling soil-borne bacterial wilt, and the application of the Pseudomonas synbiotic in preventing and controlling potato bacterial wilt. Background Art

[0002] Bacterial wilt is a soil-borne disease caused by Ralstonia solanacearum (referred to as bacterial wilt bacterium), which can cause irreversible wilting and death of crops such as potatoes, tomatoes, and eggplants, resulting in serious crop yield reduction and restricting the development of agricultural economy. [1] Beneficial rhizosphere Pseudomonas has the effects of promoting plant growth and inhibiting pathogenic bacteria, and is a very important biocontrol microorganism. At present, Pseudomonas has a significant effect on preventing and controlling bacterial wilt of crops such as tomatoes and eggplants. [2] However, the genotypes of the pathogenic bacterial wilt bacteria infecting potatoes are different from those of the bacterial wilt bacteria infecting tomatoes, tobacco, etc., resulting in different sequence variants (sequevars) and pathogenic mechanisms of the bacterial wilt bacteria infecting different plants [3-4] , and the plant hosts that can be infected are also different. Therefore, it is urgent to explore beneficial Pseudomonas that can effectively prevent and control potato bacterial wilt. [5] In the process of screening Pseudomonas and verifying its antibacterial effect, people often use a medium with relatively rich nutrients. However, the types and quantities of resources in the soil are relatively limited. After Pseudomonas is applied to the soil, it cannot obtain sufficient and matching resources, so it cannot effectively colonize in the soil environment, and its biocontrol efficiency often decreases.

[0003] Therefore, it is necessary to find resources - rhizosphere prebiotics - that can efficiently promote the rhizosphere growth and antibacterial ability of Pseudomonas, provide a suitable growth resource environment for Pseudomonas in the soil, and enhance its ability to prevent and control soil-borne bacterial wilt bacteria in potatoes. The combination of rhizosphere beneficial bacteria and their prebiotics is called rhizosphere synbiotics. Different crop root exudates (rhizosphere nutrient environment) and rhizosphere microbial community compositions are different, and the rhizosphere beneficial bacteria, prebiotics, and their combinations (synbiotics) suitable for each crop are also different [6] . Therefore, it is urgent to screen prebiotics for potatoes that can efficiently improve the prevention and control of soil-borne bacterial wilt by Pseudomonas, construct a potato Pseudomonas synbiotic formula, and prevent and control potato soil-borne bacterial wilt. [7]

[0004] References:

[0005] [1] Geng Mingyan, Liu Jianyang, Lin Wei, Hong Tianlong, Yan Ding, Kong Fanyu, Wang Jing, Cai Xianjie. Screening, identification of an acid-tolerant antagonistic bacterium and its inhibitory effect on Ralstonia solanacearum [J]. Chinese Tobacco Science, 2023, 44(02): 58 - 65 + 73.​

[0006] [2] Li Bide. Study on the Characteristics of Two Biocontrol Bacteria (Paenibacillus polymyxa and Pseudomonas fluorescens) in Controlling Tobacco Bacterial Wilt [D]. Southwest University, 2018.

[0007] [3] Jiang G, Wei Z, Xu J, et al. Bacterial Wilt in China: History, Current Status, and Future Perspectives. 2017, Frontiers in Plant Science. doi:10.3389 / fpls.2017.01549.

[0008] [4] Fabienne V, Stéphane G. Ralstonia solanacearum: An Arsenal of Virulence Strategies and Prospects for Resistance. 2023, Annual Review of Phytopathology 2023 61:1, 25 - 47.

[0009] [5] Hu J, Wei Z, Friman V P, et al. Probiotic diversity enhances rhizosphere microbiome function and plant disease suppression. MBio, 2016, 7(6): e01790 - 16.

[0010] [6] Qiu Rui, Li Xiaojie, Bai Jingke, Chen Yuguo, Yao Chenxiao, Su Xinhong, Zhang Yingying, Fang Wenyi, Li Caihong, Liu Chang, Xu Min, Song Ruifang, Li Shujun. Screening and Identification of Biocontrol Pseudomonas for Tobacco Fusarium Root Rot [J]. Acta Tabacaria Sinica: 1 - 12.

[0011] [7] Shen Jianbo, Bai Yang, Wei Zhong, et al. Rhizosphere Life Community: Academic Ideas and Cross - Innovation in Coordinating Resources, Environment, and Food Security [J]. Acta Pedologica Sinica, 2021, 58(04): 805 - 813. Summary of the Invention

[0012] Regarding the following two problems: 1) Due to limited nutrients in the soil, when applying Pseudomonas to control soil-borne diseases, Pseudomonas often has difficulty multiplying in large numbers in the soil and exerting its due control effect; 2) The physiological races of Ralstonia solanacearum infecting different crops are different, the root exudates (rhizosphere nutritional environment) and the composition of rhizosphere microbial communities of different crops are different, and the rhizosphere beneficial bacteria, prebiotics and their combinations (synbiotics) suitable for such crops are also different. The inventor found through experiments that in an indoor microplate system, both N-acetyl-L-tyrosine and troxerutin can promote the inhibitory ability of Pseudomonas PSE7 against Ralstonia solanacearum. Especially, the effect of N-acetyl-L-tyrosine is more obvious, which can significantly promote the inhibitory ability of Pseudomonas PSE7 against Ralstonia solanacearum; in greenhouse pot experiments, when N-acetyl-L-tyrosine is used in combination with Pseudomonas PSE7 and applied to the soil by the root irrigation method, the disease index of potato soil-borne bacterial wilt can be significantly reduced. It shows that the combined application of N-acetyl-L-tyrosine and Pseudomonas PSE7 can reduce the incidence of potato bacterial wilt and control potato soil-borne bacterial wilt.

[0013] The object of the present invention is to provide a Pseudomonas strain PSE7 and the application of Pseudomonas strain PSE7 in controlling bacterial wilt, as well as a Pseudomonas synbiotic for controlling soil-borne bacterial wilt containing the above-mentioned Pseudomonas, and the application of the Pseudomonas synbiotic in controlling potato bacterial wilt.

[0014] The object of the present invention is achieved by the following technical solutions:

[0015] The Pseudomonas strain PSE7, classified and named as Pseudomonas mohnii, was deposited at the General Microbiological Center of the China Committee for Culture Collection of Microorganisms on July 28, 2023. Address: No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing. The deposit number of the strain is CGMCC No. 28053.

[0016] Another object of the present invention is to provide the application of the above-mentioned Pseudomonas strain PSE7 in controlling soil-borne bacterial wilt.

[0017] Another object of the present invention is to provide the application of the above-mentioned Pseudomonas strain PSE7 in combination with resource substances in controlling soil-borne bacterial wilt.

[0018] The resource substance is N-acetyl-L-tyrosine or troxerutin, preferably N-acetyl-L-tyrosine.

[0019] Preferably, the application is to apply the resource substance and Pseudomonas PSE7 to the rhizosphere soil of crops by the root irrigation method.

[0020] Preferably, the soil-borne Ralstonia solanacearum is potato soil-borne Ralstonia solanacearum.

[0021] Another object of the present invention is to provide a Pseudomonas synbiotic for preventing and controlling soil-borne bacterial wilt, which is composed of Pseudomonas strain PSE7 and one selected from N-acetyl-L-tyrosine and troxerutin.

[0022] Preferably, the Pseudomonas synbiotic is applied by root irrigation, and 0.05 - 0.15 mmol of resource substance and 10 mL of Pseudomonas bacterial suspension with a concentration of 1×10 7 - 1×10 9 CFU / mL are applied to each potato seedling.

[0023] Another object of the present invention is to provide a method for preventing and controlling soil-borne bacterial wilt of potatoes, including: applying the above-mentioned Pseudomonas synbiotic into the soil by root irrigation; wherein, 0.05 - 0.15 mmol of resource substance and 10 mL of Pseudomonas bacterial suspension with a concentration of 1×10 7 - 1×10 9 CFU / mL are applied to each potato seedling.

[0024] Preferably, 30 days after sowing potato cuttings, N-acetyl-L-tyrosine and Pseudomonas bacterial suspension are applied into the soil by root irrigation.

[0025] Preferably, 0.1 mmol of resource substance and 10 mL of Pseudomonas bacterial suspension with a concentration of 1×10 8 CFU / mL are applied to each potato seedling.

[0026] The above-mentioned resource substance is applied in the form of a solution. Generally, the concentration of the resource substance solution is 0.1 mol / L. The preparation method of the resource substance solution is: the resource substance is dissolved in deionized water or warm water, and then sucked with a sterile syringe and filtered through a 0.22 μm filter membrane to obtain the resource substance solution.

[0027] The concentration of the Pseudomonas bacterial suspension is 1×10 7 - 10 9 CFU / mL, preferably 1×10 8 CFU / mL.

[0028] The Pseudomonas bacterial suspension is prepared by the following method: Strain PSE7 is activated using TSA solid medium; a single colony of PSE7 is picked into TSA liquid medium and cultured with shaking at 28 - 30 °C for 14 - 18 h. After centrifugation, the upper layer of TSA liquid medium is discarded, and the residual medium is removed by washing with sterile water. The bacterial cells are collected and the concentration of the bacterial suspension is adjusted with sterile water to obtain the Pseudomonas bacterial suspension.

[0029] Preferably, the rotation speed of the shaking culture is 170 rpm.

[0030] Preferably, the centrifugation conditions are centrifugation at 6000 rpm for 5 - 8 min.

[0031] Preferably, the method for removing the residual culture medium by washing with sterile water is as follows: blowing and washing the precipitate with sterile water, centrifuging at 6000 rpm for 5 - 8 min, blowing and washing the precipitate with sterile water again, centrifuging at 6000 rpm for 5 - 8 min, and blowing and washing with sterile water and centrifuging for a total of 3 times.

[0032] Advantages of the present invention:

[0033] The present invention combines N-acetyl-L-tyrosine with Pseudomonas PSE7 to form a Pseudomonas synbiotic for controlling soil-borne bacterial wilt, which can significantly improve the inhibitory ability of Pseudomonas PSE7 against Ralstonia solanacearum, and at the same time can reduce the incidence of potato bacterial wilt and control soil-borne bacterial wilt. Description of the drawings

[0034] Figure 1 It is a phylogenetic tree established by the neighbor-joining method based on the 16S rDNA gene sequence of Pseudomonas PSE7.

[0035] Figure 2 It is the effect of N-acetyl-L-tyrosine and troxerutin on the growth inhibition of soil-borne Ralstonia solanacearum by Pseudomonas PSE7.

[0036] Figure 3 It is the effect of N-acetyl-L-tyrosine on the disease index of potato soil-borne bacterial wilt.

[0037] Biological material preservation information

[0038] PSE7, classified and named as Pseudomonas mohnii, was deposited at the General Microbiological Center of the China National Committee for Culture Collection of Microorganisms on July 28, 2023. Address: No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing. The deposit number of the strain is CGMCC No. 28053. Detailed implementation manners

[0039] The technical solutions of the present invention will be further described below in conjunction with the specific implementation manners.

[0040] TSA solid medium: peptone 15.0 g, soy peptone 5.0 g, NaCl 5.0 g, agar 20.0 g, made up to 1 L with distilled water, pH 7.5, sterilized at 115 °C for 30 min.

[0041] TSA liquid medium: peptone 15.0 g, soy peptone 5.0 g, NaCl 5.0 g, made up to 1 L with distilled water, pH 7.5, sterilized at 115 °C for 30 min.

[0042] NB medium: 3 g / L beef extract, 0.5 g / L yeast powder, 5 g / L peptone, 10 g / L glucose, made up to 1 L with deionized water, sterilized at 115 °C for 30 min.

[0043] NA medium: 20 g / L agar was added to the NB medium and sterilized at 115 °C for 30 min.

[0044] 1 / 10 NB medium: 900 mL of deionized water was added to 100 mL of NB medium and sterilized at 115 °C for 30 min.

[0045] Ralstonia solanacearum HZAU43, this strain is the model pathogen of Ralstonia solanacearum in the present invention and can cause bacterial wilt in potatoes (Fabienne V, Stéphane G. Ralstonia solanacearum: An Arsenal of Virulence Strategies and Prospects for Resistance. [J]. Annual review of phytopathology, 2023.).

[0046] Experimental Example 1

[0047] Isolation, screening and identification of Pseudomonas PSE7

[0048] Isolation of soil Pseudomonas

[0049] The dilution plate coating method was used to isolate Pseudomonas. Isolation of Pseudomonas: Measure 90 mL of distilled water and add it to a 250 mL conical flask (10 - 12 glass beads were placed in the flask), sterilize at 121 °C for 30 min. Take 10 g of tomato rhizosphere soil infected with Ralstonia solanacearum from Nanchang City, Jiangxi Province, put it into the above conical flask, shake at 28 °C and 180 r / min for 30 min, use a pipette to absorb 1 mL of the soil suspension, transfer it into a test tube containing 9 mL of sterile water, mix well, and sequentially dilute to obtain soil suspensions with different dilution degrees. Absorb 100 μL of the soil suspension and spread it on the TSA solid medium plate, culture at 30 °C for 2 d, pick out the Pseudomonas colonies for purification and save them on a slant.

[0050] Screening and identification of antagonistic Pseudomonas

[0051] The antibacterial activity of the isolated Pseudomonas was determined by the plate confrontation method, and the strain with the best effect was screened out. Specifically: Ralstonia solanacearum HZAU43 was cultured in a shaking flask in NB medium. After 24 h, the OD 600 value was measured, and it was prepared into a Ralstonia solanacearum suspension with sterile water (OD 600= 1.0), a sterile atomizer was used to evenly spray the Ralstonia solanacearum bacterial suspension onto the NA medium plate; the isolated Pseudomonas was cultured for 2 days, punched into bacterial cakes with a puncher (Φ = 6 mm), and transferred to the center of the NA medium plate containing Ralstonia solanacearum, and cultured at 28 °C for 2 days, and the diameter of the inhibition zone was measured. Strains with good antagonistic effects were screened out: Pseudomonas strains from the tomato rhizosphere soil infected with Ralstonia solanacearum in Nanchang City, Jiangxi Province (115°51′E, 28°41′N), named PSE7, and its 16S rRNA was identified. The 16S rRNA sequence of this strain was compared and analyzed with those in the Genbank database, and then a phylogenetic tree was constructed using the neighbor-joining method with MEGA 7.1 software ( Figure 1 ). The results showed that this strain was Pseudomonas mohnii.

[0052] Strain PSE7, classified and named Pseudomonas mohnii, was deposited in the General Microbiology Center of the China Microbial Culture Collection Management Committee on July 28, 2023, at the address: No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing, and the strain deposit number was CGMCC No. 28053.

[0053] Example 2

[0054] Investigate the indoor effect of resource substances on Pseudomonas inhibiting soil-borne Ralstonia solanacearum

[0055] Materials: Ralstonia solanacearum HZAU43 isolated from Yunnan Province.

[0056] Preparation of Pseudomonas bacterial suspension: Strain PSE7 was activated with TSA solid medium; a single colony of PSE7 was picked into TSA liquid medium and cultured at 30 °C and 170 rpm for 18 h, centrifuged at 6000 rpm for 5 min, and the upper layer of TSA liquid medium was aspirated; the precipitate was washed with sterile water, centrifuged at 6000 rpm for 5 min, and sterile water was added again to wash the precipitate and centrifuged at 6000 rpm for 5 min. The precipitate was washed and centrifuged 3 times with sterile water to wash away the residual medium, and the bacteria were collected. The OD of the bacterial suspension was adjusted with sterile water 600 to 0.5 (corresponding to 1×10 8 CFU / mL) to obtain the Pseudomonas bacterial suspension.

[0057] Preparation of Ralstonia solanacearum HZAU43 bacterial suspension: Ralstonia solanacearum HZAU43 was inoculated onto an NA medium plate, and the plate was placed in an incubator at 30 °C for 2 d until single colonies appeared; single colonies on the plate were picked and transferred to NB medium, cultured overnight at 30 °C and 170 rpm. Fresh bacterial liquid was taken, centrifuged at 4500 rpm for 5 min at room temperature, the cells were collected, washed 3 times with sterile normal saline (0.85% NaCl) to remove the medium, and the concentration of the Ralstonia solanacearum bacterial suspension was adjusted to OD 600 = 0.5 to obtain the Ralstonia solanacearum HZAU43 bacterial suspension for use.

[0058] Experimental setup: Experimental group 1 (Pseudomonas PSE7 + N-acetyl-L-tyrosine resource group): Added the fermentation broth of Pseudomonas PSE7 cultured with N-acetyl-L-tyrosine and the Ralstonia solanacearum suspension; Experimental group 2 (Pseudomonas PSE7 fermentation broth + troxerutin resource group): Added the fermentation broth of Pseudomonas PSE7 cultured with troxerutin and the Ralstonia solanacearum suspension; Control group (only adding PSE7 fermentation broth group): Added the fermentation broth of PSE7 cultured without resource substances and the Ralstonia solanacearum suspension, and replaced the resource substances with an equal volume of sterile water.

[0059] Preparation of the fermentation broth of Pseudomonas PSE7 cultured with N-acetyl-L-tyrosine or troxerutin: Add 1335 μL of TSA liquid medium, 15 μL of Pseudomonas bacterial suspension (final concentration of 1×10 6 CFU / mL) and 150 μL of the resource substance mother liquor (the preparation method of the resource substance solution is: the resource substance is dissolved in deionized water, aspirated with a sterile syringe, and filtered through a 0.22 μm filter membrane to obtain the resource substance solution, and the final concentration of N-acetyl-L-tyrosine or troxerutin is 0.1 mM) in a 24-well plate (Costar), with 6 replicates for each treatment. After loading the samples, the 24-well plate was placed in a constant temperature (30 °C) shaker and continuously shaken at 170 r / min for 48 h, centrifuged at 4000 rpm for 5 min, carefully aspirated the supernatant, centrifuged again at 4000 rpm for 10 min, took the supernatant, combined the two supernatants, and filtered through a sterile 0.22 μm aqueous filter membrane to collect the sterile fermentation broth of Pseudomonas PSE7 in the experimental group.

[0060] Preparation of the fermentation broth of Pseudomonas PSE7: Add 1335 μL of TSA liquid medium, 15 μL of Pseudomonas bacterial suspension (final concentration of 1×10 6(CFU / mL), 150 μL of sterile water, with 6 replicates. After adding the samples, the 24-well plate was placed in a constant temperature (30 °C) shaker and continuously shaken at 170 r / min for 48 h, centrifuged at 4000 rpm for 5 min, carefully aspirated the supernatant, centrifuged again at 4000 rpm for 10 min, took the supernatant, combined the two supernatants, filtered through a sterile 0.22 μm aqueous filter membrane, and the sterile fermentation broth of Pseudomonas aeruginosa PSE7 in the control group was collected.

[0061] In the experimental group, 178 μL of 1 / 10 NB medium, 20 μL of the sterile fermentation broth of Pseudomonas aeruginosa PSE7 in the experimental group, and 2 μL of the bacterial suspension of Ralstonia solanacearum HZAU43 (OD 600 = 0.5) were added to a 96-well plate (Costar), so that the initial OD 600 value of Ralstonia solanacearum in the 96-well cell culture plate was 0.05. In the control group, 178 μL of 1 / 10 NB medium, 20 μL of the sterile fermentation broth of Pseudomonas aeruginosa PSE7 in the control group, and 2 μL of the bacterial suspension of Ralstonia solanacearum HZAU43 (OD 600 = 0.5) were added to a 96-well plate (Costar), so that the initial OD 600 value of Ralstonia solanacearum in the 96-well cell culture plate was 0.05. Blank control group: No fermentation broth was added, 2 μL of the suspension of Ralstonia solanacearum HZAU43, 20 μL of sterile water, and 178 μL of 1 / 10 NB medium were added. Six replicates were set for each treatment group. The 96-well cell culture plate was placed in a constant temperature shaker at 30 °C and continuously cultured at a rotation speed of 170 rpm for 48 h. The optical density OD 600 value was measured with an enzyme-linked immunosorbent assay (ELISA) to judge the effect of the fermentation broth of Pseudomonas aeruginosa on Ralstonia solanacearum HZAU43.

[0062] The results are shown in Figure 2 and Table 1. Compared with the blank control group, the growth amount of Ralstonia solanacearum in the control group and the two experimental groups decreased significantly. Compared with the control group, the growth amount of Ralstonia solanacearum in the two experimental groups decreased significantly, and the growth amount of Ralstonia solanacearum in experimental group 1 was the lowest, indicating that N-acetyl-L-tyrosine could significantly enhance the ability of Pseudomonas aeruginosa PSE7 to inhibit Ralstonia solanacearum (P < 0.05).

[0063] Table 1. Effects of resource substances on the ability of Pseudomonas aeruginosa PSE7 to inhibit the growth of Ralstonia solanacearum

[0064]

[0065] Example 3

[0066] Effect of resource substances on improving the prevention and control of potato bacterial wilt by Pseudomonas aeruginosa

[0067] According to the ability of resource substances to enhance the ability of Pseudomonas to inhibit Ralstonia solanacearum, the optimal resource substance was screened out as N-acetyl-L-tyrosine. Further, a pot experiment was conducted to investigate the effect of the above resource substances on Pseudomonas reducing the disease index of potatoes.

[0068] The preparation of the Pseudomonas PSE7 bacterial suspension is shown in Experimental Example 2.

[0069] Preparation of the Ralstonia solanacearum HZAU43 bacterial suspension: Ralstonia solanacearum HZAU43 was inoculated onto an NA medium plate, and the plate was placed in an incubator at 30 °C for 2 days until single colonies appeared; a single colony on the plate was picked and transferred to NB medium, cultured overnight at 30 °C and 170 rpm. Fresh bacterial liquid was taken, centrifuged at room temperature at 4500 rpm for 5 min, the cells were collected, washed 3 times with sterile normal saline (0.85% NaCl) to remove the medium, and the concentration of the Ralstonia solanacearum bacterial suspension was adjusted to OD 600 = 0.5 (corresponding to 1×10 8 CFU / mL) to obtain the Ralstonia solanacearum HZAU43 bacterial suspension for use.

[0070] Potato variety: Xindaping potato.

[0071] The potatoes were placed under natural conditions at room temperature and ventilation for natural sprouting. The potatoes with the same germination degree, healthy and plump were cut into pieces, then disinfected with 0.1% sodium hypochlorite solution for 10 min, rinsed several times with sterile water, and the potato tubers were placed on a clean bench and air-dried naturally at room temperature. The tubers were sown into a seedling-raising pot filled with 700 g of Guangxi soil (the soil accounted for about 2 / 3 of the height of the seedling-raising pot), and one potato tuber was sown into each seedling-raising pot. The sowing distance was about 3 cm from the soil surface, and the cultivation was carried out in a greenhouse. After 30 days of seedling raising, the following treatments were set: 1) PSE7 + resource substance group: Pseudomonas and N-acetyl-L-tyrosine were evenly poured into the soil near the roots of the potatoes by the root irrigation method. 1 mL of 0.1 mol / L N-acetyl-L-tyrosine solution (prepared with deionized water, the preparation method was the same as in Example 2; the amount of resource substance applied to each potato seedling was 0.1 mmol) was introduced into each potato seedling, and at the same time, 10 mL of Pseudomonas PSE7 bacterial suspension with a concentration of 10 8 CFU / mL (10 9 CFU of Pseudomonas PSE7 was introduced into each potato seedling) was introduced; 2) PSE7 group: Pseudomonas was poured into the soil near the roots of the potatoes by the root irrigation method. 10 mL of Pseudomonas PSE7 bacterial suspension with a concentration of 10 8 CFU / mL (10 9CFU Pseudomonas aeruginosa PSE7), while pouring 10 mL of water to replace the resource substance; 3) Control group: Pour 20 mL of water into the soil attached to the roots of the potatoes. After 7 days, each potato seedling in the three treatments was also inoculated with 1 mL of a suspension of Ralstonia solanacearum HZAU43 at a concentration of 1×10 8 CFU / mL (each potato seedling was inoculated with 10 8 CFU of Ralstonia solanacearum HZAU43). After inoculating with Ralstonia solanacearum, once the potato shows disease symptoms, the disease situation is recorded.

[0072] The plant disease level is divided into 5 levels (Ciampi-Panno L, Fernandez C, Bustamante P, et al. Biological control of bacterial wilt of potatoes caused by Pseudomonas solanacearum[J]. American Potato Journal, 1989, 66(5): 315-332.): 0 = no disease symptoms, 1 = disease symptoms appear in the plant parts with 1-2 true leaves, 2 = disease symptoms appear in 3 leaves to 1 / 3 of the whole plant's leaves, 3 = disease symptoms appear in 1 / 3-1 / 2 of the whole plant's leaves, 4 = disease symptoms appear in 1 / 2-3 / 4 of the whole plant's leaves, 5 = the whole plant dies. The disease situation is characterized by the disease index, and the calculation formula is (Kempe J. Biological control of bacterial wilt of potatoes: attempts to induce resistance by treating tubers with bacteria.[J]. Plant Disease, 1983, 67(5): 499-503):

[0073] Plant disease index = [∑(number of diseased plants at each level × corresponding level) / (total number of plants surveyed × highest level value)]

[0074] Biocontrol rate = [(disease index after inoculating with Ralstonia solanacearum - disease index of the experimental treatment) / disease index after inoculating with Ralstonia solanacearum] × 100%

[0075] The results are as Figure 3 shown in Table 2, and it is found that: The combined use of N-acetyl-L-tyrosine and Pseudomonas aeruginosa PSE7 has a significantly better control effect on potato soil-borne bacterial wilt than the use of a single Pseudomonas aeruginosa, can significantly reduce the disease index of potato soil-borne bacterial wilt (P<0.05), and the biocontrol effect on potatoes is 82.5%, reducing the incidence degree of bacterial wilt.

[0076] Table 2. Effects of resource substances on the reduction of potato disease index by Pseudomonas PSE7

[0077]

Claims

1. Pseudomonas strain PSE7, classified and named as Pseudomonas mosselii Pseudomonas mohnii , was deposited at the General Microbiological Center of the China Committee for Culture Collection of Microorganisms on July 28, 2023, with the deposit number of CGMCC No. 28053.

2. Use of the Pseudomonas strain PSE7 described in claim 1 in the prevention and control of soil-borne bacterial wilt disease.

3. Use of the Pseudomonas strain PSE7 described in claim 1 and a resource substance in the combined prevention and control of soil-borne bacterial wilt disease, wherein the resource substance is N-acetyl-L-tyrosine or troxerutin.

4. According to the use described in claim 3, it is characterized in that: in the said use, the resource substance and Pseudomonas PSE7 are applied to the rhizosphere soil of crops by the root irrigation method.

5. According to the use described in claim 3, it is characterized in that: the said soil-borne bacterial wilt disease is potato soil-borne bacterial wilt disease.

6. A Pseudomonas synbiotic for the prevention and control of potato soil-borne bacterial wilt disease, it is characterized in that: it is composed of the Pseudomonas strain PSE7 described in claim 1 and one selected from N-acetyl-L-tyrosine and troxerutin.

7. A method for the prevention and control of potato soil-borne bacterial wilt disease, it is characterized in that: Apply the Pseudomonas synbiotics described in claim 6 to the soil by the root irrigation method; apply 0.05 - 0.15 mmol of resource substance and 10 mL of Pseudomonas bacterial suspension with a concentration of 1×10 7 - 1×10 9 CFU / mL to each potato seedling; wherein, the resource substance is N-acetyl-L-tyrosine or troxerutin.

8. According to the method for the prevention and control of potato soil-borne bacterial wilt disease described in claim 7, it is characterized in that: Apply 0.1 mmol of resource substance and 10 mL of a Pseudomonas suspension with a concentration of 1×10 8 CFU / mL to each potato seedling.

9. According to the method for the prevention and control of potato soil-borne bacterial wilt disease described in claim 7, it is characterized in that: the Pseudomonas bacterial suspension is prepared by the following method: the strain PSE7 is activated using a TSA solid medium; a single colony of PSE7 is picked and inoculated into a TSA liquid medium, and cultured with shaking at 28 - 30 °C for 14 - 18 h, centrifuged, the upper layer of TSA liquid medium is aspirated and discarded, the residual medium is removed by washing with sterile water, the bacterial cells are collected, and the concentration of the bacterial suspension is adjusted with sterile water to obtain the Pseudomonas bacterial suspension.

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