Identification Of Resistance To Clubroot Disease And Detection Of Resistance Gene Loci In Chinese Cabbage

Since 2009,the Taibai high mountain vegetables in Shaanxi Province have been threatened by clubroot disease,which has seriously restricted the development of the local vegetable production.Therefore,investigating the resistance level of clubroot disease in Chinese cabbage varieties and the distribution and utilization of resistance genes of clubroot disease,wchich enables the security of Taibai Mountain vegetable production,is imperative.This study uses the Williams system to identify the physiological races of eight unknown clubroot pathogens collected from clubroot epidemic areas,including Yuxi city,Yunnan province,Chongqing Fuling,Yichang city,Hubei province,Shenyang city,Liaoning and Taibai region,Shaanxi province.Then,single-bacteria inoculation and the mixed bacteria inoculation were used to identify the resistances of seedling stage in 74 Chinese cabbages varieties.Afterwards,different pathogens,which collected from the 8 epidemic areas,were applied to identify resistances of seedling stages in the 10 resistant varieties of 74 Chinese cabbage varieties.After that,74 Chinese cabbage varieties were utilized to identify their field disease resistances at the Taibai beigou vegetable base in Shaanxi province.Finally,65 molecular markers linked to 14 clubroot resistance genes,including Crr1a,Crr1b,Crr2,Crr3,CRa,CRb,CRb^kato,CRc,CRd,CRk,Pb Ba8.1,Crr A5,Rcr1 and Rcr2,which located on chromosomes 1,2,3,5 and 8,were used for molecular detection of the Chinese cabbages.The research results are as followed:1.Identification of physiological races of Plasmodiophara brassicae WoronPathogens collected from Yuxi city,Yunnan province,Yichang city,Hubei province,Chongqing Fuling,Shaanxi Taibai Beigou vegetable base and Shaanxi Taibai Tangkou vegetable base are race 4.Pathogen collected from Fangcaiguan vegetable base is race7,and its counterpart collected from Liaoning city,Shenyang province is race 11.The pathogenicity of differen Pathogens are ranked from high to low:Shaanxi Beigou vegetable base+Tangkou vegetable base>Yuxi city,Yunnan province>Shaanxi Tangkou vegetable base>Shaanxi Beigou vegetable base>Chongqing Fuling>Yichang city,Hubei province>Shaanxi Fangcaiguan vegetable base.2.Inoculation on seedling stage and investigation of field disease resistanceThere were 2 high-resistance varities,which is known as“Shennong Vegetable 2613”and“Nongda 110”,among investigation of single-bacterial inoculation resistance,double-bacterial inoculation,and field disease resistance.The results of two resistence identification methods,including single-bacterial inoculation and field disease,on seedling stage in high-resistance,susceptible and high-sensitivity subjects,are in highly coincident.The mixed Clubroot pathogens made up of pathogens collected from the Taibai Beigou vegetable base and the Taibai tangkou vegetable base has a higher pathogenicity than the single bacteria collected from the Taibai Beigou vegetable base.3.Detection of resistance gene locus in resistant varietiesThe study found 11 resistance genes in 74 Chinese cabbage varieties,which is located on the A01,A03,and A05 chromosomes respectively,and the number of resistance genes located on the A03 chromosome is the most than other chromosomes.Most of the 74 tested materials had CRa resistance genes,accounting for 85.1%,and the proportion of resistance genes carried in the subjects was ranked from high to low:CRa>Rcr1>CRb^kato>-A3>Crr3>Pb Ba8.1>Crr2>Crr A5>CR-A3>CRb>Crd.The Chinese cabbage variety named"legend"carried the most resistance genes,including Crr2,Crr3,CRa,CRb^kato,PbBa8.1,CR-A3,Rcr1,-A3 and CrrA5.