Genetic analysis on the composition of resistance gene(s) in Chinese differential host Zhong 4 of yellow rust fungi

Chinese. 中4是中国小麦条锈菌生理小种的重要鉴别寄主之一。采用常规杂交遗传分析法和花粉母细胞染色体镜检,明确中4抗条锈病基因遗传组成，并探讨利用中国春ph1b突变体分析小麦近缘属（种）抗条锈病基因。将中4分别与中国春ph1b突变体和感病品种铭贤169杂交，对亲本及其杂交后代进行苗期抗条锈性鉴定和遗传分析，发现中4对条锈菌小种CY31和CY32的抗病性由1对显性基因控制；通过等位性分析和抗谱比较，发现中4对小种CY32的抗病基因与T.spelta album、Moro及K733中的抗条锈病基因不同，对中国春ph1b突变体×中4组合的F2代植株染色体数目及其核型变化的研究表明，F2代单株的抗条锈性与来自中间偃麦草X组染色体增加有关，并导致F2单株染色体数目发生变化，且X组染色体在F2代群体对小种CY31表现为抗病和感病植株中随机分布。

English. The variety Zhong 4 was one of the Chinese differential hosts for Puccinia striiformis f.sp. tritici. The general genetic analysis and chromosome identification of pollen mother cells under microscope were applied to characterize the genetic composition of resistance gene(s) in Zhong 4 to Puccinia striiformis and to discuss the analysis method for the yellow rust resistance gene(s) in wheat-related genus or species with Chinese spring ph1b mutant in present study. The parents and progeny plants of the crosses of Zhong 4 with susceptible varieties Chinese spring ph1b mutant and Mingxian 169 respectively were inoculated in seedling stage to identify their resistance to yellow rust fungi. The results indicated that the resistance of Zhong 4 to the pathotypes CY31 and CY32 of P. striiformis was probably controlled by one dominant gene. Through allelic analysis and resistance spectrum identification of Zhong 4 to pathotypes of P. striiformis, the resistance gene in Zhong 4 to CY32 was different from those in the varieties such as T. spelta album, Moro and K733. Based on the investigation of chromosome number and karyotypes in F2 plants of Chinese spring ph1b×Zhong 4, we found that the F2 plant resistance to yellow rust fungi was related to the addition of chromosomes from Th. Intermedium X genome, and the changes of chromosome number in F2 plants was due to the addition of Th. intermedium X genome chromosomes, which distributed randomly among the F2 resistant and susceptible plants to CY31.