Abstract
Pm21, derived from wheat wild relative Dasypyrum villosum, is one of the most effective powdery mildew resistance genes and has been widely applied in wheat breeding in China. Mapping and cloning Pm21 are of importance for understanding its resistance mechanism. In the present study, physical mapping was performed using different genetic stocks involving in structural variations of chromosome 6VS carrying Pm21. The data showed that 6VS could be divided into eight distinguishable chromosomal bins, and Pm21 was mapped to the bin FLb4–b5/b6 closely flanked by the markers 6VS-08.6 and 6VS-10.2. Comparative genomic mapping indicated that the orthologous regions of FLb4–b5/b6 carrying Pm21 were narrowed to a 117.7 kb genomic region harboring 19 genes in Brachypodium and a 37.7 kb region harboring 5 genes in rice, respectively. The result was consistent with that given by recent genetic mapping in diploid D. villosum. In conclusion, this study demonstrated that physical mapping based on chromosomal structural variations is an efficient method for locating alien genes in wheat background.
Highlights
Common wheat (Triticum aestivum L.) is one of the most important cereal crops
B1 and b10 were in NAU419, b4 and b8 were in NAU418, and b3 and b5 were in Y18-S6
Several genetic stocks involving in chromosomal structural changes of 6VS have been reported [4,6,7,11], which allows to physically map Pm21 in common wheat
Summary
Common wheat (Triticum aestivum L.) is one of the most important cereal crops. Wheat production is seriously threatened by powdery mildew caused by Blumeria graminis f. The powdery mildew resistance gene Pm21, originating from Dasypyrum villosum Candargy (2n = 14, VV), confers highly effective resistance to all known isolates of Bgt [1,2]. As the donor of Pm21, wheat-D. villosum translocation line T6AL.6VS has been widely applied in wheat breeding. More than 20 varieties with this translocated chromosome have been planted on an accumulated area of more than four million hectares in China [3]. Up to now, little is known about the nature of Pm21 and its resistance mechanism. It is essential to map and clone Pm21
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