Genetic characterization and cloning of the barley M1-a locus

大麦的白粉病，由专性真菌引起 小麦白粉病菌sp. hordei，提供了几个优点 用于研究介导抗性的宿主基因。 这种疾病 经过50多年的深入研究， 广泛的生理数据和遗传物质基础 这是大多数其他宿主/病原体系统无法比拟的。 大麦M1-a基因座特别令人感兴趣，因为其超过 在该位点上共鉴定出30个抗性等位基因。 通过 筛选118，000 M2幼苗，我已经分离出41部分或 完全易感的突变体 这些新的互补分析 等位基因将用于确定M1-a的遗传结构 基因座，它可以代表一个复杂的基因座或集群， 紧密相连的基因 此外，突变体将被利用， 消减杂交实验分离M1-a cDNA克隆。 目前还没有从任何植物中克隆出这样的抗病基因。 对M1-a克隆的分析将提供关于 M1-a基因座的等位基因变异的性质以及 M1-a基因产物在介导疾病中的生化作用 resistance.*//

The powdery mildew disease of barley, caused by the obligate fungal pathogen Erysiphe graminis f. sp. hordei, offers several advantages for the study of host genes mediating resistance. This disease has been studied intensively for more than 50 years; thus, there is an extensive base of physiological data and genetic materials available that is unmatched by most other host/pathogen systems. The barley M1-a locus is of particular interest in that more than 30 resistance alleles have been identified at this locus. By screening 118,000 M2 seedlings, I have isolated 41 partially or fully susceptible mutants. Complementation analysis of these new alleles will be used to determine the genetic structure of the M1-a locus, which may represent either a complex locus or cluster of tightly linked genes. Also, the mutants will be exploited in subtractive hybridization experiments to isolate M1-a cDNA clones. No such disease resistance gene has been cloned from any plant. Analysis of the M1-a clones will provide information about the nature of the allelic variation at the M1-a locus and about the biochemical role of the M1-a gene product in mediating disease resistance.***//