Abstract：
Rice blast is one of the main diseases in rice and can occur in different rice growth stages. Due to the complicated procedure of panicle blast identification and instability of panicle blast infection influenced by the environment, most cloned rice resistance genes are associated with leaf blast. In this study, a rice panicle blast resistance gene, Pb2, was identified by genome-wide association mapping based on the panicle blast resistance phenotypes of 230 Rice Diversity Panel 1 (RDP1) accessions with 700,000 single-nucleotide polymorphism (SNP) markers. A genome-wide association study identified 18 panicle blast resistance loci (PBRL) within two years, including 9 reported loci and 2 repeated loci (PBRL2 and PBRL13, PBRL10 and PBRL18). Among them, the repeated locus (PBRL10 and PBRL18) was located in chromosome 11. By haplotype and expression analysis, one of the Nucleotide-binding domain and Leucine-rich Repeat (NLR) Pb2 genes was highly conserved in multiple resistant rice cultivars, and its expression was significantly upregulated after rice blast infection. Pb2 encodes a typical NBS-LRR protein with NB-ARC domain and LRR domain. Compared with wild type plants, the transgenic rice of Pb2 showed enhanced resistance to panicle and leaf blast with reduced lesion number. Subcellular localization of Pb2 showed that it is located on plasma membrane, and GUS tissue-staining observation found that Pb2 is highly expressed in grains, leaf tips and stem nodes. The Pb2 transgenic plants showed no difference in agronomic traits with wild type plants. It indicated that Pb2 could be useful for breeding of rice blast resistance.
摘要：
稻瘟病是水稻的主要病害之一,可发生在水稻的不同生长阶段。由于囊胚鉴定过程复杂，且受环境影响，囊胚感染不稳定，大多数克隆的水稻抗性基因与叶瘟病有关。在这项研究中,水稻抗穗病基因，Pb2是根据具有700,000个单核苷酸多态性（SNP）标记的230个水稻多样性组1（RDP1）种质的抗穗病表型，通过全基因组关联图谱鉴定的。一项全基因组关联研究在两年内确定了18个抗穗病基因座（PBRL），包括9个报告基因座和2个重复基因座（PBRL2和PBRL13，PBRL10和PBRL18）。其中,重复位点(PBRL10和PBRL18)位于11号染色体。通过单倍型和表达分析,一个核苷酸结合域和富含亮氨酸的重复序列（NLR）Pb2基因在多个抗性水稻品种中高度保守，稻瘟病侵染后其表达显著上调。Pb2编码具有NB-ARC结构域和LRR结构域的典型NBS-LRR蛋白。与野生型植物相比，转基因Pb2水稻对穗病和叶病的抗性增强，病斑数量减少。Pb2的亚细胞定位显示它位于质膜上,GUS组织染色观察发现Pb2在谷粒中高表达,叶尖和茎节。Pb2转基因植株与野生型植株在农艺性状上无差异。表明Pb2可用于水稻抗稻瘟病育种。
