中文摘要：

Xα21是最早克隆的水稻抗病基因，作为类受体激酶类广谱抗病基因它受到广泛的关注。转基因Xα21材料，很可能成为世界上第一个被批准进行大田释放的水稻转基因材料。文章在简要回顾Xα21的发现、定位和克隆过程之后，总结了目前Xα21基因的抗病作用机理和育种应用研究现状，包括XA21蛋白质激酶的生化特性、AvrXα21的鉴别、Xα21介导的抗病途径、抗病机理等，并对今后的研究进行了展望。

英文摘要：

Germ Xα21 is the first disease resistance gene cloned from rice （ Oryzo sativa L. ）, which encodes a receptor-like kinase and confers broad spectrum resistance against Xanthomonas oryzae pv. oryzae （Xoo）. In this paper, the discovery, mapping and cloning of Xα21 were reviewed briefly. The molecular mechanism of resistance and its breeding application, including biochemical properties of the kinase domain of XA21, AvrXα21 identification, the disease resistance pathway mediated by Xα21, and the mechanism of disease resistance were summarized. Future perspective on Xα21-related research is also discussed.