Bacterial Blight Resistance in Rice

Bacterial blight (BB) caused by Xanthomonas oryzae pv. oryzae (Xoo) is one of the major constraints for sustainable production of rice. Some factors affecting pathogenicity of Xoo. In rice, a number of genes contributing to qualitative and quantitative resistance against Xoo have been characterized. At least 37 major disease resistance (MR) genes have been identified and named, and 7 (Xa1, Xa3/Xa26, xa5, xa13, Xa21, xa25, and Xa27) of them have been isolated. Importantly, some key components functioning in Xa3/Xa26- and Xa21-mediated defense signaling pathways have been characterized, which is helpful to understand molecular mechanisms of qualitative resistance to BB. At least 74 resistance quantitative trait locus (QTLs) against Xoo have been identified in different rice cultivars interacting with different Xoo strains. One major resistance QTL (WRKY45) and eight minor resistance QTLs (NRR, WRKY13, OsDR8, MPK6, GH3-1, GH3-2, GH3-8, and C3H12) have also been identified.