Unraveling rice defense against bacterial blight: Molecular pathways, resistance genes and breeding perspectives

Bacterial blight, caused by Xanthomonas oryzae pv. oryzae (Xoo), is one of the most destructive diseases affecting rice (Oryza sativa L.), threatening food security across major rice-growing regions, particularly in Asia. The pathogen is known for its rapid transmission, high mutation rate, and ability to cause yield losses of up to 40 to 50 percent under favorable conditions. Developing and deploying resistant rice varieties remains the most effective strategy for disease management. In this review, we summarize the molecular mechanisms underlying rice immunity to Xoo, focusing on the two major defense layers: pattern-triggered immunity (PTI) and effector-triggered immunity (ETI). We categorize and analyze 44 reported bacterial blight resistance (R) genes, detailing their structure, classification, and regulatory roles in immune signaling. Furthermore, we highlight advances in the identification, functional characterization, and breeding applications of these genes. Finally, we discuss current challenges and future prospects in engineering durable resistance through a deeper understanding of host-pathogen interactions and integrated immune responses. This review aims to provide valuable insights for researchers and breeders working toward sustainable control of rice bacterial blight.