Isolation,Identification And Diversity Of Pathogens Of Potato Common Scab In Some Areas Of Gansu Province

Potato common scab(PCS)is a plant disease caused by pathogenic Streptomyces,which can cause tuber plants to produce sickle-like lesions,which significantly reduce the quality of potatoes and spread widely around the world.In C hina,the potato industry has continued to develop,but the area of potato common scab disease has expanded year by year,which has already had an important impact on potatoes and related industries.This study mainly processed potato samples collected in some areas of Gansu(Wuwei,Zhangye,Baiyin,Pingliang,Tianshui,Longnan),isolated Streptomyces,pathogenicity verification and physiological and biochemical tests,and systematically analyzed the area.The pathogen type of potato scab provides a theoretical basis for the prevention and treatment of potato scab in related areas.The main findings are:A total of 53 potato samples were collected in Wuwei,Zhangye,Baiyin,Pingliang,Tianshui,Longnan areas.After isolation and purification,246 actinomycetes were obtained,of which 67 strains of pathogenic genes contained Streptomyces,accounting for 27.24%of all Streptomyces.By PCR amplification of the three major pathogenic genes(txtAB,nec1,tomA)of the pathogenic gene island(PAI),it was found that the PAI types of potato scab pa thogens in the above areas have certain diversity,and their pathogenic gene types are different.txtAB~+/nec1~+/tomA~+(65 strains),txtAB~+/nec1~-/tomA~+(1 strain),and txtAB~-/nec1~-/tomA~+(1strain).After 16S rDNA sequencing and system identification,the main pathogens in Zhangye area were S.galilaeus,the main pathogens in Wuwei area were S.bobili,and the main pathogens in Baiyin area were S.bobili,S.galilaeus,the main pathogens in the Pingliang and Tianshui area are S.scabies,and the main pathogen in Longnan is S.galilaeus.The pathogenicity of some isolated pathogens was verified.The results showed that 16#,73#,76#(txtAB~+/nec1~-/tomA~+),93#,156#,214#strains could obviously infect the small potato chips and the small potato chips produced black or brown necrosis;but 31#bacteria(txtAB~-/nec1~-/tomA~+)did not produce obvious infection;in the radish seedling inhibition test,all the test strains can produce the growth of radish seedlings different degrees of inhibition.In this study,16#,73#,76#,93#,156#,and 214#bacteria were used to test the potato tuber to different degrees of disease.The 156#bacteria treatment group had the highest morbidity.97.03%;the pathogenicity of the bacteria was well,and no obvious lesions were observed in the 31#bacteria treatment group,and the test results show that the strain has low pathogenicity.Combined with 16S rDNA sequencing and physiological and biochemical tests,it can be confirmed that 31#bacteria are S.bottropensis,156#bacteria are S.bobili,16#,76#and 93#bacteria are S.galilaeus;due to the 16S rDNA of S.europaeiscabiei and S.scabies has a high similarity.Based on the phylogenetic analysis and the results of ITS-specific sequence detection,it is further further determine that 73#and 214#bacteria are S.scabies.