Журнал патологии растений и микробиологии

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Biological Characterization and Genetic Diversity of Indian Strains of Ralstonia solanacearum Biovars 3 and 4 Causing Bacterial Wilt of Tomato

Dinesh Singh, Shweta Sinha, Garima Chaudhary and Yadav DK

Ralstonia solanacearum biovars 3 and 4 causing bacterial wilt of tomato (Solanum lycopersicum L.) is a devastating soil borne plant pathogen across the world. Eighty seven isolates of R. solanacearum were isolated from wilted tomato plants from Jammu and Kashmir, Himachal Pradesh, Uttarakhand, Jharkhand, Orissa states of India and characterized them by traditional and molecular methods. Biovar of R. solanacearum was determined using set of carbon sources and it showed that biovar 3 of R. solanacearum were found most prominent (90.2 per cent) in all the states of India, whereas biovar 4 was found in states of Jharkhand and Himachal Pradesh. The phylotype specific multiplex PCR assigned all 87 the isolates of R. solanacearum infecting tomato under phylotype I. To study the genetic diversity, BOX-PCR and multilocus sequence typing approaches were used. Amplification products yielded in BOX-PCR fingerprint pattern ranging from 500 bp -4 kb and found 23 DNA typing groups of 87 isolates of R. solanacearum at 50% similarity coefficient. Under multilocus sequence typing, three virulence genes viz., hrp (regulatory transcription regulation) and egl (endoglucanase precursor) and fli C genes of 18 strains of R. solanacearum belonging to different agro-climatic zones was done. Based on sequence analysis of egl gene, majority of the Indian strains of R. solanacearum were very close to each other except ORT-8, UTT-23 and JHT2 and there were very close to strain GMI1000. A lot of genetic variability was found in Indian isolates of R. solanacearum irrespective of place of isolation and climatic conditions.