Isolation,Identification And Diversity Of Potato Scab Pathogens In Dingxi Area

Potato common scab is responsible for important economic losses in both temperate and tropical climates.The disease is characterized by shallow,raised or deep-pitted corky lesions on potato tubers.Streptomyces-induced scab diseases are also found on a variety of tap root crops.However,the host range of strains causing common scab has rarely been determined.In this study,a large-scale sample collection of potato in Dingxi area was carried out,and the diseased potato block was treated with the disease pathogen.The pathogen Streptomyces was obtained by separating the diseased spots,and the morphological characteristics,physiological and biochemical indexes and 16S rDNA gene amplification were used to sequence and construct.The phylogenetic tree was used for taxonomic identification of the pathogen system,and its pathogenicity was verified by the radish seedling method,the small potato chip method and the pot back test.The main find of the experiments was as follows:(1)There are three types of potato scab lesions in Dingxi area,which are flat lesions,convex lesions and concave lesions.(2)A total of 204 actinomycetes were isolated from 32 diseased potato samples collected from Dingxi area.After pathogenicity detection,there were 87 pathogens,and the pathogen was 42.65%.After system identification,S.bobili with 45 strains,S.galilaeus with 30 strain,S.turgidiscabies with 10 strain,and S.reticuliscabiei with 2 strain were identified.The proportion of pathogens is 51.72%,34.48%,11.49%and 2.31%,respectively.(3)There was variation in the distribution of the pathogens among the study areas.S.bobili and S.galilaeus were the main pathogens in Dingxi area.Wheres as,S.bobili,S.galilaeus,S.turgidiscabies,and S.reticuliscabiei were the main potato scab pathogens in Lintao County.In addition,S.bobili and S.galilaeus were also the main pathogens in Anding District,Tongwei County and Longxi County.(4)The main distribution of pathogenic bacteria in Dingxi area:15 in Anding District,8in Tongwei County,40 in Lintao County,17 in Weiyuan County,and 7 in Longxi County.(5)PCR amplification of txtAB,nec1 and tomA by PAI pathogenicity island genotype identification showed that there were two types of isolated actinomycetes PAI,namely txtAB~+/nec1~+/tomA~+and txtAB~-/nec1~-/tomA~+.