Virulence and Genetic Diversity of Blumeria graminis f． sp． tritici Collected from Shandong and Hebei Provinces

Abstract

Powdery mildew caused by Blumeria graminis f.sp.tritici(Bgt) is one of the most important diseases that damages wheat(Triticum aestivum L.) production in China.Analysis of virulence structure and effectiveness of resistance genes is important in controlling powdery mildew with host resistance.This study was conducted to test virulence structures of 41 isolates collected from Shandong and Hebei provinces in 2011.The genetic diversity of these isolates was also analyzed using SSR markers.The virulence frequencies of isolates tested ranged from 0.35(Bg40-2,Yantai,Shandong) to 0.74(Bg46-1,Pingdu,Shandong).The mean virulence frequency for the isolates from Shandong Province was not significantly different from that of the isolates from Hebei Province.Except for a few resistance genes such as Pm17,the virulence frequencies of isolates from Shandong and Hebei provinces on most resistance genes were not different.None of the isolates tested was virulent on Pm24 carried by the Chinese landrace Chiyacao.A few isolates were virulent on Pm1c,Pm16,Pm20,PmH,and Mlxbd.Two isolates from Handan and Huanghua of Hebei Province were virulent on Pm21,but none of the isolates from Shandong Province was virulent on Pm21.The virulence frequencies for Pm5e,Pm6,Pm12,Pm13,Pm17,Pm40,Pm2+6,and Pm5+6 ranged from 0.18 to 0.48.Genes Pm1a,Pm3a,Pm3c,Pm3g,Pm4a,Pm4b,Pm4c,Pm5a,Pm7,Pm8,Pm19,Pm33,Pm43,PmY39,PmPS5A,and PmDR147 had the virulence frequencies over 0.6.Analysis of genetic diversity indicated that the genetic variation of Bgt isolates occurred within the population,and gene flow occurred among isolates.Although some single spore progenies from the same location were clustered together,some were not classified into the same cluster,indicating the variation in their genetic bases.The polymorphism of virulence patterns for various resistance genes was not necessarily consistent with the DNA polymorphism as revealed by SSR markers.