AUTHOR=He Huagang , Ji Yaoyong , Zhu Shanying , Li Bin , Zhao Renhui , Jiang Zhengning , Bie Tongde 

TITLE=Genetic, Physical and Comparative Mapping of the Powdery Mildew Resistance Gene Pm21 Originating from Dasypyrum villosum

JOURNAL=Frontiers in Plant Science

VOLUME=8

YEAR=2017

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2017.01914

DOI=10.3389/fpls.2017.01914

ISSN=1664-462X

ABSTRACT=<p><italic>Pm21</italic>, originating from wheat wild relative <italic>Dasypyrum villosum</italic>, confers immunity to all known races of <italic>Blumeria graminis</italic> f. sp. <italic>tritici</italic> (<italic>Bgt</italic>) and has been widely utilized in wheat breeding. However, little is known on the genetic basis of the <italic>Pm21</italic> locus. In the present study, four seedling-susceptible <italic>D. villosum</italic> lines (DvSus-1 ∼ DvSus-4) were identified from different natural populations. Based on the collinearity among genomes of <italic>Brachypodium distachyon, Oryza</italic>, and <italic>Triticeae</italic>, a set of 25 gene-derived markers were developed declaring the polymorphisms between DvRes-1 carrying <italic>Pm21</italic> and DvSus-1. Fine genetic mapping of <italic>Pm21</italic> was conducted by using an extremely large F<sub>2</sub> segregation population derived from the cross DvSus-1/DvRes-1. Then <italic>Pm21</italic> was narrowed to a 0.01-cM genetic interval defined by the markers 6VS-08.4b and 6VS-10b. Three DNA markers, including a resistance gene analog marker, were confirmed to co-segregate with <italic>Pm21</italic>. Moreover, based on the susceptible deletion line Y18-S6 induced by ethyl methanesulfonate treatment conducted on Yangmai 18, <italic>Pm21</italic> was physically mapped into a similar interval. Comparative analysis revealed that the orthologous regions of the interval carrying <italic>Pm21</italic> were narrowed to a 112.5 kb genomic region harboring 18 genes in <italic>Brachypodium</italic>, and a 23.2 kb region harboring two genes in rice, respectively. This study provides a high-density integrated map of the <italic>Pm21</italic> locus, which will contribute to map-based cloning of <italic>Pm21</italic>.</p>