The article "A Receptor Kinase-Like Protein Encoded by the Rice Disease Resistance Gene, Xa21" by Wen-Yuan Song, Guo-Liang Wang, Li-Li Chen, et al., published in *Science* in 1995, reports the positional cloning of the rice gene Xa21, which confers resistance to the bacterial pathogen *Xanthomonas oryzae pv. oryzae* race 6. The gene was isolated through transgenic experiments, and 50 transgenic rice plants carrying the cloned Xa21 gene displayed high levels of resistance to the pathogen. The predicted protein sequence of Xa21 contains both a leucine-rich repeat motif and a serine-threonine kinase-like domain, suggesting its role in cell surface recognition of pathogen ligands and subsequent activation of intracellular defense responses. The study highlights the importance of cellular signaling processes in plant disease resistance and suggests that the Xa21 gene represents an uncharacterized class of plant disease resistance genes. The findings also indicate that intergeneric transfer of disease resistance genes may provide resistance to pathogens in recipient species.The article "A Receptor Kinase-Like Protein Encoded by the Rice Disease Resistance Gene, Xa21" by Wen-Yuan Song, Guo-Liang Wang, Li-Li Chen, et al., published in *Science* in 1995, reports the positional cloning of the rice gene Xa21, which confers resistance to the bacterial pathogen *Xanthomonas oryzae pv. oryzae* race 6. The gene was isolated through transgenic experiments, and 50 transgenic rice plants carrying the cloned Xa21 gene displayed high levels of resistance to the pathogen. The predicted protein sequence of Xa21 contains both a leucine-rich repeat motif and a serine-threonine kinase-like domain, suggesting its role in cell surface recognition of pathogen ligands and subsequent activation of intracellular defense responses. The study highlights the importance of cellular signaling processes in plant disease resistance and suggests that the Xa21 gene represents an uncharacterized class of plant disease resistance genes. The findings also indicate that intergeneric transfer of disease resistance genes may provide resistance to pathogens in recipient species.