Microsatellite high‐density mapping of the stripe rust resistance gene YrH52 region on chromosome 1B and evaluation of its marker‐assisted selection in the F₂ generation in wild emmer wheat

Abstract

A new stripe rust resistance gene, YrH52, derived from the unique Mount Hermon population of wild emmer wheat (Triticum dicoccoides) in Israel, was previously located on chromosome 1B. The main objectives of the present study were to increase marker density in the vicinity of the YrH52 gene using additional microsatellite markers, and to evaluate the accuracy and efficiency of marker-assisted selection on this gene in the F # generation. By means of 70 additional microsatellite primer pairs, 150 individuals of the F # mapping population were genotyped. Among 202 marker loci, 20 were found to be linked to the YrH52 gene with log-likelihood (LOD) scores ranging from 3.84 to 58.82, and linkage distances ranging from 0.33 to 41.39 cM. A genetic map was constructed of chromosome 1B, consisting of 23 markers and the YrH52 gene, with a total map length of 149.5 cM. Most of the markers were located in the region close to YrH52, which was flanked by Xgwm413 and Xgwm273a with map distances of 1.3 and 2.7 cM, respectively. The accuracy and efficiency of marker-assisted selection were calculated as AMAS and EMAS, respectively, for homozygous resistant genotypes of YrH52 gene in the F # generation. AMAS and EMAS for homozygous resistant genotypes of the YrH52 gene in the F # generation showed linear and significant negative correlation with the map distance between marker and target gene or between the two bracketing markers. It was concluded that the YrH52 region on chromosome 1B is significantly more enriched by microsatellite markers than the previously published map ; that a single microsatellite marker is efficient for marker-assisted selection of homozygous resistant genotypes of YrH52 gene in the F # generation when the map distance is 5.0 cM ; and that when two markers are used AMAS can be dramatically improved and becomes relatively stable, whereas EMAS will not be obviously improved and will still vary linearly with map distance.

Molecular Genetic Maps in Wild Emmer Wheat, Triticum dicoccoides: Genome-Wide Coverage, Massive Negative Interference, and Putative Quasi-Linkage

“…Recently, Röder et al (1998) developed a set of hexaploid wheat microsatellite markers, and constructed a molecular map consisting of 279 microsatellite loci amplified by 230 primer sets. The efficiency of these primer sets in analysis of T. dicoccoides genomic DNA was demonstrated previously both for mapping (Chagué et al 1999;Peng et al 1999Peng et al , 2000 and population genetics purposes (Fahima et al 1998;Li et al 2000). Seventy-nine of these microsatellite markers were integrated into the above-mentioned RFLP-linkage map in durum wheat (Korzun et al 1999).…”

DNA and morphological markers for a Russian wheat aphid resistance gene

“…The effectiveness of markers for MAS was evaluated by calculating accuracy and efficiency using the empirical formula proposed by Peng et al (2000). Accuracy of a marker is calculated by the number of homozygous resistant plants among the total number of plants containing the resistant parent-type marker multiplied by 100.…”

An EST-SSR marker, bu099658, and its potential use in breeding for yellow rust resistance in wheat

“…This being the purpose, many molecular markers, such as Restriction Fragment Length Polymorphisms (RFLPs) (Helentjaris et al 1986), Random Amplified Polymorphic DNAs (RAPDs) (Williams et al 1990), Amplified Fragment Length Polymorphisms (AFLPs) (Vos et al 1995), Resistance Gene Analogs (RGAs) (Kanazin et al 1996) and Simple Sequence Repeats (SSRs) (Akkaya et al 1992) have been widely used in plants. The successful utility of DNA markers has been shown in different wheat breeding programmes, namely SCAR marker (SC-Y15) for Yr17 (Sharp et al 2001), SSR markers (Xgwm413 and Xgwm273) for YrH52 (Peng et al 2000) and SSR marker (Xgwm498) for Yr26 (Yildirim et al 2004), for developing resistant wheat cultivars. Worldwide, yellow rust resistance genes Yr1-Yr48 and many provisionally designated genes have been identified in wheat and its relatives (Huang et al 2011).…”