The broad-spectrum blast resistance gene Pi9 encodes a nucleotide-binding site-leucine-rich repeat protein and is a member of a multigene family in rice
The broad-spectrum blast resistance gene Pi9 encodes a nucleotide-binding site-leucine-rich repeat protein and is a member of a multigene family in rice
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DOI：
10.1534/genetics.105.044891
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发表时间：
2006-03-01
期刊：
影响因子：
3.3
通讯作者：
Wang, GL
中科院分区：
文献类型：
--
作者：
Qu, SH;Liu, GF;Wang, GL
利用定位克隆技术克隆了水稻抗稻瘟病广谱基因Pi9。对横跨Pi9位点的76 kb细菌人工染色体（BAC）序列进行测序，鉴定出6个串联排列的具有核苷酸结合位点（NBS）和富含亮氨酸重复序列（lrr）的耐药样基因（Nbs1-Pi9-Nbs6-Pi9）。对选定的Pi9缺失突变体进行分析，并将来自BAC的45 kb片段转化为易感水稻品种TP309，将Pi9缩小到候选基因Nbs2-Pi9和Nbs3-Pi9。对携带候选基因的转基因品系的疾病评价证实Nbs2-Pi9就是Pi9基因。序列比较分析表明，Pi9位点的6个相似位点分属于4个类，基因重复可能是NBS-LRR基因簇形成的主要进化动力之一。半定量逆转录酶（RT -PCR）分析表明，Pi9在抗Pi9植物中组成性表达，不受稻瘟病侵染的诱导。克隆的Pi9基因为阐明水稻广谱抗病的分子基础和稻瘟病抗性基因簇的进化机制提供了一个起点。
The broad-spectrum rice blast resistance gene Pi9 was cloned using a map-based cloning strategy. Sequencing of a 76-kb bacterial artificial chromosome (BAC) contig spanning the Pi9 locus led to identification of six tandemly arranged resistance-like genes with a nucleotide-binding site (NBS) and leucine-rich repeats (LRRs) (Nbs1-Pi9-Nbs6-Pi9). Analysis of selected Pi9 deletion mutants and transformation of a 45-kb fragment from the BAC contig into the susceptible rice cultivar TP309 narrowed down Pi9 to the candidate genes Nbs2-Pi9 and Nbs3-Pi9. Disease evaluation of the transgenic lines carrying the individual candidate genes confirmed that Nbs2-Pi9 is the Pi9 gene. Sequence comparison analysis revealed that the six paralogs at the Pi9 locus belong to four classes and gene duplication might be one of the major evolutionary forces contributing to the formation of the NBS-LRR gene cluster. Semiquantitative reverse transcriptase (RT)-PCR analysis showed that Pi9 was constitutively expressed in the Pi9-resistant plants and was not induced by blast infection. The cloned Pi9 gene provides a starting point to elucidate the molecular basis of the broad-spectrum disease resistance and the evolutionary mechanisms of blast resistance gene clusters in rice.