A RECEPTOR KINASE-LIKE PROTEIN ENCODED BY THE RICE DISEASE RESISTANCEGENE, XA21

The rice Xa21 gene, which confers resistance to Xanthomonas oryzae pv. oryzae race 6, was isolated by positional cloning. Fifty transgenic r ice plants carrying the cloned Xa21 gene display high levels of resist ance to the pathogen. The sequence of the predicted protein, which car ries both a leucine-rich repeat motif and a serine-threonine kinase-li ke domain, suggests a role in cell surface recognition of a pathogen l igand and subsequent activation of an intracellular defense response. Characterization of Xa21 should facilitate understanding of plant dise ase resistance and lead to engineered resistance in rice.