Evaluation of resistance genes and their pyramids against rice bacterial leaf blight pathogen Xanthomonas oryzae pv. oryzae

摘要

Bacterial leaf blight (BB) is one of the most destructive diseases of rice in the Asian subcontinent and a major hurdle for increasing rice production in all rice growing countries. Breeding for resistance requires an insight into the resistant genesacting in the particular geographical location. We tested 10 isolates of the pathogen strains collected from different parts of India on a set of near isogenic lines carrying BB resistant genes in the genetic background of IR24 namely, Xa1, Xa3, Xa4, xa5, Xa7, xa8, Xa1O, xa13, Xal4 and Xa21, for the pathotype identification. In addition, various combinations of the resistance genes as gene pyramids were also tested for their resistance reaction. Pathogen strains compatible to the individual genes were present in detectable frequencies, although no strain could overcome all the resistant genes. The gene combination Xa4+xa5+xal 3+Xa21 conferred a broad spectrum of resistance to all the 10 strains, supporting the strategy of gene pyramiding of appropriateresistance genes. Greater variation was observed in the virulence pattern of the pathogen than the molecular phenotypes.