National Key Facility for Crop Gene Resources and Genetic Improvement (NFCRI), Institute of Crop Science, Chinese Academy of Agriculture Sciences (CAAS), Beijing 100081, China.
State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Life Sciences, South China Agricultural University, Guangzhou 510642, China.
Mol Plant. 2015 Feb;8(2):290-302. doi: 10.1016/j.molp.2014.10.010. Epub 2014 Dec 15.
The majority of plant disease resistance (R) genes encode proteins that share common structural features. However, the transcription activator-like effector (TALE)-associated executor type R genes show no considerable sequence homology to any known R genes. We adopted a map-based cloning approach and TALE-based technology to isolate and characterize Xa23, a new executor R gene derived from wild rice (Oryza rufipogon) that confers an extremely broad spectrum of resistance to bacterial blight caused by Xanthomonas oryzae pv. oryzae (Xoo). Xa23 encodes a 113 amino acid protein that shares 50% identity with the known executor R protein XA10. The predicted transmembrane helices in XA23 also overlap with those of XA10. Unlike Xa10, however, Xa23 transcription is specifically activated by AvrXa23, a TALE present in all examined Xoo field isolates. Moreover, the susceptible xa23 allele has an identical open reading frame of Xa23 but differs in promoter region by lacking the TALE binding element (EBE) for AvrXa23. XA23 can trigger a strong hypersensitive response in rice, tobacco, and tomato. Our results provide the first evidence that plant genomes have an executor R gene family of which members execute their function and spectrum of disease resistance by recognizing the cognate TALEs in the pathogen.
大多数植物疾病抗性 (R) 基因编码具有共同结构特征的蛋白质。然而，转录激活子样效应物 (TALE) 相关执行器类型 R 基因与任何已知的 R 基因没有显著的序列同源性。我们采用基于图谱的克隆方法和 TALE 技术，从野生稻 (Oryza rufipogon) 中分离和鉴定出一个新的执行器 R 基因 Xa23，该基因赋予对由稻黄单胞菌 pv. 引起的细菌性枯萎病的广谱抗性oryzae (Xoo)。Xa23 编码一个 113 个氨基酸的蛋白质，与已知的执行器 R 蛋白 XA10 具有 50%的同一性。XA23 中的预测跨膜螺旋也与 XA10 的跨膜螺旋重叠。然而，与 Xa10 不同的是，Xa23 的转录是由 AvrXa23 特异性激活的，AvrXa23 是所有检测到的 Xoo 田间分离物中存在的一种 TALE。此外，易感 xa23 等位基因具有与 Xa23 相同的开放阅读框，但在启动子区域缺失了用于识别 AvrXa23 的 TALE 结合元件 (EBE)。XA23 可以在水稻、烟草和番茄中引发强烈的过敏反应。我们的研究结果首次提供了证据表明，植物基因组具有一个执行器 R 基因家族，其成员通过识别病原体中的同源 TALEs 来执行其功能和疾病抗性谱。
