Intra-regional diversity of rice bacterial blight pathogen, Xanthomonas oryzae pv. oryzae, in the Andaman Islands, India: revelation by pathotyping and multilocus sequence typing.

Genotyping and pathotyping of sland isolates revealed seven pathotypes distributed in two clonal complexes with strong indications for trans-boundary movement and consequent diversification of the bacterial pathogen. Highly virulent pathotypes of X. oryzae pv. oryzae that could overcome combinations of R-genes, xa13+Xa21 as well as xa5+xa13 were found prevalent in the Andaman Islands SIGNIFICANCE AND IMPACT OF THE STUDY: Genetic and virulence analysis of X. oryzae pv. oryzae in the Andaman Islands revealed introduction and host-mediated regional diversification and local adaptation of X oryzae pv. oryzae. The study calls for the need of multi-gene pyramiding for durable disease resistance and establishing stringent quarantine measures for safeguarding island agricultural practices in the future.