Genetic Characterization and Cloning of the Barley Ml-a Locus

9402315萨默维尔大麦的白粉病，由专性真菌病原体小麦白粉病菌（Erysiphe graminis f.）sp. hordei，为研究宿主基因介导的抗性提供了几个优势。 这种疾病已经被深入研究了50多年;因此，有一个广泛的基础生理数据和遗传材料，这是大多数其他宿主/病原体系统无法比拟的。 大麦Ml-a基因座特别令人感兴趣，因为在该基因座上已经鉴定了超过30个抗性等位基因。 通过对118，000株M_2幼苗的筛选，分离出41株部分或完全感病的突变体。 这些新等位基因的互补分析将用于确定Ml-a基因座的遗传结构，其可以代表复杂的基因座或紧密连锁的基因簇。 此外，将在消减杂交实验中利用突变体以分离Ml-a cDNA克隆。 还没有从任何植物中克隆出这样的抗病基因。 Ml-a克隆的分析将提供关于Ml-a基因座处等位基因变异的性质和关于Ml-a基因产物在介导抗病性中的生物化学作用的信息。 ***

9402315 Somerville 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 that 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 Ml-a locus is of particular interest in that more that 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 Ml-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 isolated Ml-a cDNA clones. No such disease resistance gene has been cloned form any plant. %%% Analysis of the Ml-a clones will provide information about the nature of the allelic variation at the Ml-a locus and about the biochemical role of the Ml-a gene product in mediating disease resistance. ***