水稻抗稻瘟病基因Pi47的精细定位和候选基因分析

不断挖掘和克隆抗稻瘟病新基因, 是解析水稻抗病分子遗传机制和培育抗稻瘟病新品种的重要基础。Pi47是笔者从广谱、持久抗稻瘟病湖南地方品种湘资3150中鉴定的稻瘟病抗性基因, 前期研究将其初步定位于第11染色体标记RM224和RM5926间。本研究利用3个Pi47单基因系与感病亲本CO39杂交F₂群体1687个感病单株对Pi47精细定位, 利用6个STS标记对3个单基因系进行背景分析, 采用生物信息学方法进行了候选基因分析。结果表明, Pi47被精细定位于CAPS标记S32与K33间0.24 cM区域的171.2 kb物理区间内, 背景分析将Pi47进一步缩小至SC12和K33间67.8 kb的区间内; 该区间含有8个结构基因, 其中2个编码NBS-LRR抗病类似蛋白, 为Pi47的候选功能基因。稻瘟菌抗谱比较分析发现, Pi47单基因系与其定位区间内4个Pik位点的等位基因Pik、Pikm、Pikh和Pikp的近等基因系抗谱不同。这些结果为进一步克隆Pi47和利用其进行分子标记辅助选择培育抗稻瘟病水稻新品种奠定了基础。

Fine Mapping and Candidate Gene Analysis of Rice Blast Resistance Gene Pi47

Continuous mapping and cloning new blast resistance genes provided an important approach for revealing the molecular mechanism of resistance to rice disease and breeding new varieties resistant to rice blast. Previously, the blast resistance gene Pi47 was mapped between SSR markers RM224 and RM2956 on chromosome 11, from a broad-spectrum and durable resistance native cultivar Xiangzi 3150 in Hunan province. In this study, the fine mapping and candidate gene prediction were performed, showing that Pi47 was mapped in an interval of 0.24 cM between CAPS markers S32 and K33 with 171.2 kb on Nipponbare reference genome, and further narrowed in an interval of 67.8 kb between markers SC12 and K33, through background screening to Pi47 monogenic lines and susceptible parent CO39 with six STS markers. Eight genes were predicted in this region on the reference genome, among them two encoded NBS-LRR resistance-like proteins, which probably were Pi47 functional candidate genes. A blast resistance spectrum evaluation, using Pi47 monogenic lines and four near-isogenic lines with the Pik allelic gene Pik, Pikm, Pikh, and Pikp across Pi47 region, revealed that Pi47 shared different resistance spectra with these four alleles. These results shed light on further molecular cloning of Pi47, and the molecular marker will be useful for molecular maker assisted selection to breed new resistant cultivars.