PLoS ONE (Jan 2014)

Fine physical and genetic mapping of powdery mildew resistance gene MlIW172 originating from wild emmer (Triticum dicoccoides).

  • Shuhong Ouyang,
  • Dong Zhang,
  • Jun Han,
  • Xiaojie Zhao,
  • Yu Cui,
  • Wei Song,
  • Naxin Huo,
  • Yong Liang,
  • Jingzhong Xie,
  • Zhenzhong Wang,
  • Qiuhong Wu,
  • Yong-Xing Chen,
  • Ping Lu,
  • De-Yun Zhang,
  • Lili Wang,
  • Hua Sun,
  • Tsomin Yang,
  • Gabriel Keeble-Gagnere,
  • Rudi Appels,
  • Jaroslav Doležel,
  • Hong-Qing Ling,
  • Mingcheng Luo,
  • Yongqiang Gu,
  • Qixin Sun,
  • Zhiyong Liu

DOI
https://doi.org/10.1371/journal.pone.0100160
Journal volume & issue
Vol. 9, no. 6
p. e100160

Abstract

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Powdery mildew, caused by Blumeria graminis f. sp. tritici, is one of the most important wheat diseases in the world. In this study, a single dominant powdery mildew resistance gene MlIW172 was identified in the IW172 wild emmer accession and mapped to the distal region of chromosome arm 7AL (bin7AL-16-0.86-0.90) via molecular marker analysis. MlIW172 was closely linked with the RFLP probe Xpsr680-derived STS marker Xmag2185 and the EST markers BE405531 and BE637476. This suggested that MlIW172 might be allelic to the Pm1 locus or a new locus closely linked to Pm1. By screening genomic BAC library of durum wheat cv. Langdon and 7AL-specific BAC library of hexaploid wheat cv. Chinese Spring, and after analyzing genome scaffolds of Triticum urartu containing the marker sequences, additional markers were developed to construct a fine genetic linkage map on the MlIW172 locus region and to delineate the resistance gene within a 0.48 cM interval. Comparative genetics analyses using ESTs and RFLP probe sequences flanking the MlIW172 region against other grass species revealed a general co-linearity in this region with the orthologous genomic regions of rice chromosome 6, Brachypodium chromosome 1, and sorghum chromosome 10. However, orthologous resistance gene-like RGA sequences were only present in wheat and Brachypodium. The BAC contigs and sequence scaffolds that we have developed provide a framework for the physical mapping and map-based cloning of MlIW172.