investigation of pathogenisity and genotypic diversity of xanthomonas oryzae pv. oryzae caused rice bacterial blight

to investigation of pathogenisity and genotype diversity of xanthomonas oryzae pv. oryzae (xoo) caused rice bacterial blight, several samples were collected from paddy field of rice in rasht-sangar, soumeh sara, rezvan shahr, daboudasht amol and rice-institute-research guilan during the summer of 2012, from plants that showed blight and yellowing in their leaves. bacterial isolates were identified according to phenotypic and molecular characteristics. among isolated bacterial strains 17 isolates were selected for further investigations. isolates grouped into three pathogenisity groups based on virulence against susceptible international rice cultivar tetep. the genetic diversity of 17 isolates analyzed by using repetative extragenomic polymorphism (rep-pcr). cluster analysis based on 33 polymorphic rep markers showed three different genotypic groups among isolates with at least 62% similarity. the results showed limit correlation between different pathogenisity and genotypic groups of x.oryzae pv. oryzae.