Isolation And Identification Of Pathogen Of Potato Common Scab In Baicheng Xinjiang And Screening Of Antagonistic Bacteria

Potato common scab(PCS)is a soil-borne disease caused by Streptomyces spp..The surface of infected potato tuber forms scab,and the tissue around the scab becomes cork,which reduces the quality of potato tuber and poses a serious threat to potato industry.At present,the prevention and control of potato scab is mainly based on chemical control,but chemical agents have a low control effect on soil-borne diseases and serious pollution to the soil environment,and the pathogen is easy to produce resistance to the chemical agent.Biological control can improve the efficiency of control and reduce environmental pollution,which is in line with the development requirements of green agriculture in China.In this study,the pathogen were isolated and identified from infected potato samples collected in Baicheng County,Aksu Prefecture,Xinjiang,and antagonistic bacteria was screened against Potato scab,and the fermentation conditions of antagonistic bacteria were optimized.The results are as follows:(1)The disease pathogen of potato tuber was separated and purified from baicheng county in Aksu area of henchard’s town and township.According to the specific primers,pathogen virulence genes were obtained with PCR amplification,screening the strain with virulence genes.Pathogenicity of the strains containing pathogenic genes was determined by the small potato slice method and radish seedling method,and three Streptomyces strains with strong pathogenicity were found.Three pathogenic Streptomyces strains were identified as S.europaeiscabiei,S.bobili and S.glilaeus,which was reported for the first time in Xinjiang.(2)S.Bobili K6 was used to target pathogenic bacteria and the potato rhizosphere soil was isolated.Potential antagonistic strains were screened by plate confrontation method,and one strain K25-JK with a good antagonistic effect was obtained,which was identified as Pseudomonas aeruginosa by morphology and molecular biology.In the pot experiment,the incidence of potato sore was reduced from 56.52% to39.13%,the disease index was reduced from 28.7% to 19%,and the control effect was 33.8% after treatment with k25-JK.(3)The fermentation conditions of strain K25-JK were optimized.The results showed that the best antagonistic activity of carbon source was glucose,nitrogen source was beef extract,inorganic salt was Na Cl,initial p H was 7.0,liquid loading rate was 100 m L/250 m L,and inoculation rate was 3%.