Genetic Diversity Of Plasmodiophora Brassicae And The Establishment Of SCAR Markers

To determine the genetic diversity of the 48 populations of Plasmordiophora brassicae in China,out of 100 ISSR primers and 13 RAPD primers,three ISSR primers and one RAPD primers were screened out.The three ISSR primers produced44 bands totally,in which 43 bands were polymorphic?97.73%?.The number of average bands every primer produced was 14.33.The polymorphism of primer 889was the lowest among the three ISSR primers,which was 94.11%,and both the other two primers were 100%.A total of 16 bands were amplified for 48 individuals of P.brassicaeby using primer M05,in which 16 were the polymorphic bands,accounting for 100%of total bands.The ISSR UPGMA phonograms indicated that,the genetic similarity index of 48P.brassicae population varies from 0.58 to 1.00.The 48 populations clustered into two main groups,group?and group?,at a cutoff value of 0.5805.ISSR Group?clustered into different number of subgroups at different cutoff value.The 27^th population of P.brassicae from Sichuan Mianning and the 39^th population of P.brassicae from Anhui Jixi were clustered into one branch at a cutoff value of 1.00,the rest of 46 populations can be divided individually,which means there was no obvious relationship between geographic source and the genetic background of P.brassicae population.Compared the ISSR cluster results with the physiological strain race results,the populations of race 11 can be distinguished with other races.But the cluster results can't distinguish P.brassicae from the Williams level.The RAPD UPGMA phonograms indicated that,the genetic similarity index of48 P.brassicae population varies from 0.5625 to 1.00.The 48 populations clustered into two main groups,group?and group?,at a cutoff value of 0.5625.RAPD Group?clustered into different number of subgroups at different cutoff value.The23^th population of P.brassicae from Sichuan Wenjiang and the 43^th population of P.brassicae from Yunnan Lufeng were clustered into one branch and the 11^th population of P.brassicae from Sichuan Pidu and the 18^th population of P.brassicae from Sichuan Mianzhu were clustered into one branch both at a cutoff value of 1.00,the rest of 44 populations can be divided individually,which means there was no obvious relationship between geographic source and the genetic background of P.brassicae population.And there was also no correlation between the RAPD cluster results and the spread of the physiological strain race of P.brassicae.Selecting conservative bands produced by ISSR primers to recycle.Cloning,transforming and sequencing the recycle fragments,design SCAR primers according to the sequence results to run 48 populations PCR.4 designed SCAR primers could produce single band of 48 P.brassicae populations,so could be used to P.brassicae molecular identification.