ABSTRACT
18Bacterial leaf blight (BLB) is one of the main constraints to the worldwide rice production system. Various management strategies are advocated to mitigate this problem. Among these, use of resistant cultivars is the cheapest and environmentally safest way. From long back, conventional breeding approaches have been mostly adopted to generate a number of resistant cultivars in different countries. And these cultivars are gradually outdated due to the breakdown of resistance and low yield response. The host resistance is overcome by mutant strains of the pathogen with changing population dynamics of Xanthomonas oryzae pv. oryzae (Xoo). This bacterial blight resistance in rice is qualitative and quantitative in nature, where both contribute significantly to the defense response against Xoo. So far about 40 resistance genes have been identified in rice against various Xoo pathotypes and a few have been cloned and characterized to decipher the host–pathogen interaction. Various molecular approaches have been adopted to deploy them for getting a long-term durable resistance. Gene pyramiding of several resistance genes through marker assisted selection is found to be the most effective strategy. However, with changing dynamics of pathogen population in this intensified agro ecosystem, our prime aim would be to safeguard resistant durability. Continued efforts should also be paid to look forward upon the modern genomics approaches like the development of transgenic and application of genome editing tools for the crop improvement. Therefore, a thorough understanding of molecular mechanisms worked behind BLB resistance is needed.
