Identification and cloning of genes conditioning species-specific parasitism of Magnaporthe oryzae

为了阐明稻瘟病菌种属专一性的遗传机制，我们将一个小麦分离物与一个狗尾草分离物、一个燕麦分离物和一个水稻分离物杂交。利用这些杂交F_1代，我们鉴定了PWT1、PWT2(狗尾草分离物对小麦的条件无毒)、PWT3、PWT4(燕麦分离物对小麦的条件无毒性)、PWT5(水稻分离物对小麦的条件无毒性)、PFM1、PFM2(小麦分离物对谷子的条件无毒性)和PAT1(小麦分离物对燕麦的条件无毒性)。我们还鉴定了一个与PWT4相对应的抗性基因，并将其命名为Rwt4。Rwt4与PWT4一一对应，表明小麦/燕麦分离物对小麦的植物专化性受基因对基因互作的影响。从这些无毒基因中选择pWT1、PWT4和PAT1作为分子克隆的目标。通过批量分离分析，我们发现了与PWT1、PWT4和PAT1紧密连锁的分子标记。

To clarify genetic mechanisms of plant-species specificity of Magnaporthe oryzae, we crossed a Triticum isolate with a Setaria isolate, an Avena isolate, and an Oryza isolate. Using the F_1 progenies derived from these crosses, we identified PWT1, PWT2 (conditioning avirulence of the Setaria isolate on wheat), PWT3, PWT4 (conditioning avirulence of the Avena isolate on wheat), PWT5 (conditioning avirulence of the Oryza isolate on wheat), PFM1, PFM2 (conditioning avirulence of the Triticum isolate on foxtail millet), and PAT1 (conditioning avirulence of the Triticum isolate on oat). We also identified a resistance gene corresponding to PWT4, and designated it as Rwt4. Rwt4 corresponded to PWT4 in a one-to-one manner, suggesting that the plant species specificity of the Triticum/Avena isolates on wheat is conditioned by gene-for-gene interactions. From these avirulence genes, PWT1, PWT4, and PAT1 were chosen as targets for molecular cloning. Using bulked segregant analysis, we found molecular markers that are closely linked to PWT1, PWT4 and PAT1.