水稻白叶枯病候选抗性基因SHNLR的RGAs克隆及分析

旨在从含有疣粒野生稻抗白叶枯病基因的新种质SH5、SH76基因组中克隆抗病基因。利用RGAs法得到1个NBS-LRR类同源基因,暂命名为SHNLR(登录号为JF934724)。结果表明,SHNLR的开放阅读框长度为3 105 bp,编码1 034个氨基酸,含有CC、NB-ARC与LRR结构域,具备CC-NBS-LRR类植物抗病基因的结构特征。BLASTn和BLASTp比对显示SHNLR是单拷贝基因,未发现同源性较高且功能已知的基因,仅NBS保守域序列与番茄Prf基因的相似度最高。对SHNLR基因电子定位,发现其位于水稻第11号染色体的长臂末端,但与11号染色体上已定位或克隆的8个白叶枯病抗性基因具有不同序列或处于不同的位置。半定量RT-PCR分析表明,SHNLR在抗病新种质叶片中的表达明显受到白叶枯病菌Zhe173的诱导。因此推测SHNLR可能是1个与抗白叶枯病相关的R基因。

RGAs Cloning and Analysis of a Candidate Resistance Gene SHNLR to Rice Bacterial Blight

SH5 and SH76 carrying BB-resistance genes were the progenies of a cultivated japonica rice variety 8411 somatically hybridized with Oryza meyeriana.Resistance gene analogs(RGAs)method was used in this study.A NBS-LRR homologous gene was cloned from SH5 and SH76 and named as SHNLR(Accession No.JF934724).Open reading frame(ORF)of SHNLR was amplified from SH5 and SH76 cDNA by RT-PCR.ORF was 3 105 bp in length and encoded a 1 034-residue protein containing CC,NB-ARC and LRR domain,which are the characteristic domains of CC-NBS-LRR disease resistance proteins in plant.BLASTn and BLASTp indicated that SHNLR was a single copy gene and had no high homology to any functionally known genes except for high similarity to NBS of Prf in tomato.SHNLR was in silico mapped to the long arm terminal of chromosome 11,whose sequence or position was different from those of eight cloned or mapped genes in chromosome 11.Semi-quantitative RT-PCR showed that SHNLR was induced by the race Zhe173 in SH5 and SH76.Therefore,SHNLR may be a new bacterial blight resistance gene.