An overview of bacterial blight disease of rice and strategies for its management

This is a status paper on a destructive rice disease –bacterial blight (BB), caused by Xanthomonas oryzae pv. oryzae (Xoo). We review the occurrence and spread of this disease, the taxonomy and classification of the pathogen and strategies for disease management. Studies on pathogen variation have revealed that breeding with single major genes for resistance, may be ineffective due to resistance breakdown. Thus, pyramiding of resistance genes appears to be a good option for disease management. Evidence from our laboratory suggests that BB of rice can be managed through carefully selected biological control agents which can be used by themselves or can work in combination with single major genes for BB resistance (e.g. Xa4). We also present the view that elite indica rice cultivars can be constructed through traditional breeding and transgenic approaches to incorporate pyramids of blast and BB resistance genes to effectively manage these two devastating rice production constraints and to sustain rice yields in India.