Finger printing of Ralstonia solanacearum isolates by Rep-PCR and RAPD

Fifty seven isolates of Ralstonia solanacearum causing wilt on different host plants viz., tomato (Solanum lycopersicum), brinjal (Solanum melongena), potato (Solanum tuberosum), bird of paradise (BOP) (Strelitzia reginae), ginger (Zingiber officinale), chilli (Capsicum annuum), davana (Artemisia pallens) and coleus (Coleus forskohlii) were collected from different agro climatic zones of India. They were differentiated into races on the basis of their pathogenicity to infect different host. The isolates were established as race-1; none of the isolates infected mulberry and banana. Fifty four isolates oxidized and utilized both the disaccharides and sugar alcohols, thus these isolates positioned as biovars-3 as per Haywards classification system. Three isolates from Kerala, two ginger and one tomato strains were not able to utilize dulcitol and lactose. Hence, were categorized into new taxonomic group within biovar system and designated as biovar-3B for the first time in India. Fifty four isolates were confirmed as race-1, biovar-3 and 3 isolates as race-1, biovar-3B by morphological, physiological, biochemical and pathogenicity studies. Two sets of primers (OLI1 & Y2 and Y1 & Y2) were used in this study for authenticate the organism. Further, the identity of the isolates was confirmed by serological diagnostic kit obtained from International Potato Research Center, Lima, Peru and single chain variable fragment antibody specific to R. solanacearum. Isolates collected from different geographical areas of India were categorized into four major groups in Rep-PCR on the basis of 50 percent coefficient of 1.1-linkage distance. However, no relationship could be drawn regarding the biogeographical origin or host preference of the isolates among the groups. Based on RAPD analysis using 15 random decamer primers, all the isolates were classified into seven major groups/cluster.