Abstract:The variety Zhong 4 was one of the Chinese differential hosts for Puccinis 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.