论文部分内容阅读
Powdery mildew caused by Blumeriagraminis(DC.)f.sp.tritici(Bgt)is one of the most devastating diseases of wheat(Triticum aestivum L.)worldwide.More than a dozen genes against this disease,identified from wheat germplasms of different ploidy levels,have been mapped to the region surrounding the Pm1 locus on the long arm of chromosome 7A,which forms a resistance(R)gene cluster.Mlm2033 and Mlm80 from einkom wheat were two of the R genes belonging to the Pm1 cluster.This study was initiated to fine map these two genes for map-based cloning.Comparative genomics study showed that macro-colinearity exists between Brachypodium distachyon chromosome 1(Bd1)and the Mlm2033-Mlm80-Pm1a region,which allowed us to develop markers based on the wheat sequences orthologous to genes contained in the Bd1 region.With these and other newly developed and published markers,high-resolution maps were constructed for both Mlm2033 and Mlm80 using large F2 populations.Moreover,a physical map of Mlm2033 was constructed through chromosome walking with BACs and comparative mapping.Eventually,Mlm2033 and Mlm80 were restricted to a 0.12 cM and a 0.86 cM interval,respectively.Based on the closely linked common markers,Mlm2033,Mlm80,and MlIW172,another powdery mildew resistance gene in thePm1 cluster,were not allelic to one another.These results provided useful information for map-based cloning of the R genes in the Pm1 cluster and interpretation of their evolution.