Fine Mapping of Wheat Stripe Rust Resistance Gene Yr26 Based on Collinearity of Wheat with Brachypodium distachyon and Rice

Abstract

The Yr26 gene, conferring resistance to all currently important races of Puccinia striiformis f. sp. tritici (Pst) in China, was previously mapped to wheat chromosome deletion bin C-1BL-6-0.32 with low-density markers. In this study, collinearity of wheat to Brachypodium distachyon and rice was used to develop markers to saturate the chromosomal region containing the Yr26 locus, and a total of 2,341 F2 plants and 551 F2∶3 progenies derived from Avocet S×92R137 were used to develop a fine map of Yr26. Wheat expressed sequence tags (ESTs) located in deletion bin C-1BL-6-0.32 were used to develop sequence tagged site (STS) markers. The EST-STS markers flanking Yr26 were used to identify collinear regions of the rice and B. distachyon genomes. Wheat ESTs with significant similarities in the two collinear regions were selected to develop conserved markers for fine mapping of Yr26. Thirty-one markers were mapped to the Yr26 region, and six of them cosegregated with the resistance gene. Marker orders were highly conserved between rice and B. distachyon, but some rearrangements were observed between rice and wheat. Two flanking markers (CON-4 and CON-12) further narrowed the genomic region containing Yr26 to a 1.92 Mb region in B. distachyon chromosome 3 and a 1.17 Mb region in rice chromosome 10, and two putative resistance gene analogs were identified in the collinear region of B. distachyon. The markers developed in this study provide a potential target site for further map-based cloning of Yr26 and should be useful in marker assisted selection for pyramiding the gene with other resistance genes.

Toward a better understanding of the genomic region harboring Fusarium head blight resistance QTL Qfhs.ndsu-3AS in durum wheat

“…Thus, Brachypodium is more closely related to wheat than rice based on DNA sequence similarities in the genomic regions on the short arms of these three collinear chromosomes. These results are consistent with the observations reported in the previous studies (Catalan and Olmstead 2000;Draper et al 2001;Foote et al 2004;the International Brachypodium Initiative 2010;Zhang et al 2013). However, higher collinearity between wheat and rice than between wheat and Brachypodium has been observed in specific genomic regions (Faris et al 2008).…”

“…However, higher collinearity between wheat and rice than between wheat and Brachypodium has been observed in specific genomic regions (Faris et al 2008). To date, many genes in wheat have been well characterized through comparative analysis with rice and Brachypodium genomic sequences (Liu et al 2003(Liu et al , 2006Bossolini et al 2007;Faris et al 2008;Somyong et al 2011;Zhang et al 2013). Comparative analysis of the Qfhs.ndsu-3AS QTL and nearby regions on 3AS tremendously enhanced genetic as well as physical mapping of the region in this study.…”

Brachypodium as an emerging model for cereal–pathogen interactions

“…1Á92 Mb syntenic region in brachypodium harbours two RGAs. Zhang et al (2013) Phragmites spp. ), Stagonospora paspali (NH: bahiagrass; Paspalum notatum) and Stagonospora tainanensis (NH: sugarcane).…”

Fine Physical and Genetic Mapping of Powdery Mildew Resistance Gene MlIW172 Originating from Wild Emmer (Triticum dicoccoides)

“…Nevertheless, many studies have reported poor levels of micro-colinearity between wheat and rice because of inversions, deletions, duplications, and other rearrangements [6], [7], [48], [63]. The isolation of the wheat disease resistance genes Lr10 , Lr21 and Pm3 has also shown that wheat and rice have very limited colinearity in the relevant chromosomal regions.…”