Rice versus Xanthomonas oryzae pv. oryzae: a unique pathosystem

Bacterial blight, caused by Xanthomonas oryzae pv. oryzae (Xoo), is a devastating disease of rice worldwide. The qualitative or pathogen race-specific resistance to this pathogen conferred by major disease resistance (MR) genes has been widely used in rice improvement. Accumulating genetic and molecular data have revealed that the molecular mechanisms of rice qualitative resistance to Xoo are largely different from those of qualitative resistance in other plant-pathogen pathosystems. In this review, we focus on the unique features of rice qualitative resistance to Xoo based on MR genes that have been identified and characterized. The distinctiveness of the rice-Xoo interaction provides a unique pathosystem to elucidate the diverse molecular mechanisms in plant qualitative resistance.