Genetic Diversity Of Ralstonia Solanacearum Strains In China And PCR Detection Technique Of Bacterial Wilt Infection Of Potato

Bacteria wilt is one of the most important and worldwide spread plant diseases. and isdifficult to control. The causal agent, Ralstonia solanaceurum, has diversity in bothgenotype and phenotype. The distribution of R. solanacearum strains in China is quitedifferent from other countries of the world. In this study, genetic diversities of strainscollected from different locations and hosts in China were examined by RAPD analysis.The geographical origins of strains was also analyzed by using PCR amplification. A DNAfragment specific for R. solanacearum was obtained and was preliminarily used to detectisolates from potato. A more rapid, sensitive and convenient detection method is expectedto be developed.Forty-three R. solanacearum isolates collected from 11 provinces or cities in China and 4isolates obtained from other countries were amplified using 15 random primers by PCR.Similar DNA fingerprints were obtained in using primers OPB11, OPA15, OPE1 andOPZ10．and 1 to 5 bands were performed respectively. Potato isolates showed identicalprofiles when the primers OPB7, OPA30 were used. High level diversity was found amongdifferent isolates when using primers OPA14, OPG6, OPG14, OPF5, OPK14, OPK20, andOPK17．Two groups were clustered from RAPD data. Group A can be divided into 7subgroup (A1, A2, A3, A4-A5, A6, A7) : and A1 involves 2 types (A1-1, A1-2) . Group Bcan be divided into two subgroups (B1 and B2) , which contain three types (B1-1,B1-2,B1-3; B2-1, B2-2, B2-3, respectively).RAPD group A includes 27 potato isolates from different location, which are mainlybelonging to race 3 (biovarⅡ).Group B consists of 20 isolates from plant hosts other than potato and different locations,belonging to different races and biovars. RAPD groups in this study are not related tolocation sources but closely related to hosts.The geographical origin of R. solanacearum strains in China was preliminarily analyzed byPCR. Potato isolates are belonging to division 1 "Americatum". whereas other isolates,division 2 "Asiaticum". These results are coincided to RAPD grouping.A DNA fragment specific for R. solanacearum was screened out according to RAPDanalysis. A pair of Primers for PCR was constructed based on the sequencing results. PCRamplification produced the expected 773bp products only from R. solanacearum strains,but not from other species of potato bacterial pathogens.Using the PCR amplified method, the 773bp fragment obtained from bacteria wilt diseasedpotato tuber. This provides a basis to develop a more effective method for detection of R.solanacearum infection.