Guo Changjiang, Sun Xiaoguang, Chen Xiao, Yang Sihai, Li Jing, Wang Long, Zhang Xiaohui
State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, 210023, China.
Institute for Research on Cancer and Ageing, Nice (IRCAN), University of Nice, Nice, France.
Plant Mol Biol. 2016 Jan;90(1-2):95-105. doi: 10.1007/s11103-015-0398-7. Epub 2015 Nov 3.
Most rice blast resistance genes (R-genes) encode proteins with nucleotide-binding site (NBS) and leucine-rich repeat (LRR) domains. Our previous study has shown that more rice blast R-genes can be cloned in rapidly evolving NBS-LRR gene families. In the present study, two rapidly evolving R-gene families in rice were selected for cloning a subset of genes from their paralogs in three resistant rice lines. A total of eight functional blast R-genes were identified among nine NBS-LRR genes, and some of these showed resistance to three or more blast strains. Evolutionary analysis indicated that high nucleotide diversity of coding regions served as important parameters in the determination of gene resistance. We also observed that amino-acid variants (nonsynonymous mutations, insertions, or deletions) in essential motifs of the NBS domain contribute to the blast resistance capacity of NBS-LRR genes. These results suggested that the NBS regions might also play an important role in resistance specificity determination. On the other hand, different splicing patterns of introns were commonly observed in R-genes. The results of the present study contribute to improving the effectiveness of R-gene identification by using evolutionary analysis method and acquisition of novel blast resistance genes.
大多数稻瘟病抗性基因（R基因）编码具有核苷酸结合位点（NBS）和富含亮氨酸重复序列（LRR）结构域的蛋白质。我们之前的研究表明，在快速进化的NBS-LRR基因家族中可以克隆到更多的稻瘟病R基因。在本研究中，选择了水稻中两个快速进化的R基因家族，从三个抗病水稻品系的旁系同源基因中克隆一部分基因。在九个NBS-LRR基因中总共鉴定出八个功能性稻瘟病R基因，其中一些对三种或更多稻瘟病菌株具有抗性。进化分析表明，编码区的高核苷酸多样性是决定基因抗性的重要参数。我们还观察到，NBS结构域关键基序中的氨基酸变异（非同义突变、插入或缺失）有助于NBS-LRR基因的稻瘟病抗性能力。这些结果表明，NBS区域在抗性特异性的决定中可能也起着重要作用。另一方面，在R基因中通常观察到内含子的不同剪接模式。本研究结果有助于通过进化分析方法提高R基因鉴定的有效性，并有助于获得新的稻瘟病抗性基因。
