小麦Mlo及NBS-LRR类抗病基因同源序列的分离与鉴定

根据GenBank中公布的大麦白粉病抗性控制基因Mlo cDNA序列及一个来源于栽培一粒小麦(Triticum monococcum L.)的假定抗病基因序列分别设计引物,以携带小麦抗白粉病基因的近等基因系为材料进行RT-PCR筛选.结果获得两个表达基因的cDNA克隆.其中一个与大麦白粉病抗性控制基因Mlo的同源性达83%.另一个为非通读序列,含有两个可能的开放阅读框,分别包含抗病基因NBS保守结构域2和3以及与水稻抗稻瘟病基因Pib蛋白末端相似的13个LRR区域,推测该序列属于NBS-LRR类.白粉菌诱导前后,该片段RT-PCR扩增产物存在差异,表明该片段可能与小麦抗病性相关.利用"中国春"缺体-四体系,将该NBS-LRR类序列定位在小麦1D染色体上.

Isolation and Characterization of Mlo and NBS-LRR-like Gene Sequences in Wheat

Based on both cDNA sequence of barley powdery mildew resistance control element Mlo and DNA sequence of the known putative disease resistance gene from Triticum monococcum L., we designed some primers to amplify resistant homologous sequences in the near isogenic lines (NILs) of powdery mildew resistance using RT-PCR method. Two expressed cDNA fragments were isolated from wheat genome. One showed 83% homology to the Mlo gene of barley. The other contained two possible open reading frames (ORFs). NBS conservative domains 2, 3 of disease resistance gene and 13 LRR structures similar to rice Pib protein terminal were found respectively in the two ORFs. It indicated that the latter fragment belongs to NBS-LRR-like genes. The obvious difference of RT-PCR products was observed between the before challenged and the challenged for 72 h by Blumeria graminis f. sp. tritici, which implied that this sequence could be associated with disease resistance of wheat. Using nulli-tetrasomic lines of “Chinese Spring", the NBS-LRR-like gene had been located on chromosome 1D. Key words:Mlo; NBS-LRR; cDNA cloning; NIL; RGA