AFLP Analysis Of Dominant Population And Establishment Of SU11-14 SCAR Marker Of Puccinia Striiformis West In China

Yellow (stripe) rust ,caused by Puccinia striiformis f. sp. tritici, is one of the most important diseases of wheat in China. The current strategy for management of wheat stripe rust is use of resistant cultivars. However, this economic strategy has been hampered by the resistance breakdown of wheat cultivars. Previous research indicates this phenomenon was caused by the occurrence and development of new races of Puccinia striiformis f. sp. tritici. As a result, it is necessary for management of wheat stripe rust and use of resistant cultivars to clarify molecular genetic relations of major races and epidemic strains of Puccinia striiformis f.sp.tritici in rencent years in China and it is also necessary to understand population genetic structure of this pathogen in nature.In recent years, monitoring results from Shaanxi,Gansu,Yunnan and Shanxi indicated that The virulence rate of CY32 was the highest and became the dominant race but The variation trend of Hybrid46 group and SU11 group was the virulence rate of Hybrid46 declined, while the rate of SU11 group increased gradually. From this view, Amplified fragment length polymorphisim(AFLP) was used to fingerprint the dominant epidemic strains in rencent years, especially,SU11 group of Puccinia striiformis f.sp.tritici,the pathogen of wheat stripe rust and analysis virulence characterisc of pathogen, and random amplified polymorphic DNA(RAPD) was used to analysis polymorphisims and find especial DNA band of eight pathotypes in SU11 group.The results as follows:1. Ten AFLP primer pairs of nineteen primer pairs selected in the research were used to analyze twelve races or pathotypes of Puccinia striiformis f.sp.tritici and the result show that: DNA bands amplified with different primer pairs were 23 to 61 and the band length was mainly between 200 base pairs and 750 base pairs; sixty-two percent of 431 bands in total obtained with ten AFLP primer pairs were polymorphic.2.AFLP was used to fingerprint the dominant epidemic strains in rencent years, especially,SU11 group of Puccinia striiformis f.sp.tritici,the pathogen of wheat stripe rust.Compared to the result of virulence characterisc of pathogen, The resuts showed that: genetic diversity of both virulence and fingerprint characteristic existed in the pathogen populations,but there was not significant correlation between the two characteristics; according to AFLP cluster analysis,different pathotypes in SU11 group don't share close evolutionary relationships and they evolve independly.3.Of the 190 random primers analyzed in this research, 94 primers can show us steady amplification profiles. The results obtained from eight pahotypes in SU11 group in China indicate that the Puccinia striiformis f.sp.tritici still has some consistent DNA sequence, but the genetic variations among types were abundance as a whole.4. In this study,the special DNA fragments of SU11-14 and SU11-4 in SU11 group were founded.One special DNA fragment of SU11-14 was cloned and sequenced. Based on the sequencing result, a primer pair was designed and the SCAR marker for SU11-14 in SU11 group was obtained.The results above indicate that AFLP is very suitable for genetic analysis,especially, genetic relationship of Puccinia striiformis f.sp. tritici and a molecular identification system for the Puccinia striiformis f.sp. tritici races could be established by means of cosmically searching special RAPD fragments of different races.