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Genetic Mapping of Major-Effect Seed Dormancy Quantitative Trait Loci on Chromosome 2B using Recombinant Substitution Lines in Tetraploid Wheat

Chao, Shiaoman, Elias, Elias, Benscher, David, Ishikawa, Goro, Huang, Yung-Fen, Saito, Mika, Nakamura, Toshiki, Xu, Steven, Faris, Justin, Sorrells, Mark
Crop science 2016 v.56 no.1 pp. 59-72
Triticum turgidum subsp. dicoccoides, Triticum turgidum subsp. durum, agronomic traits, centromeres, chromosome mapping, cultivars, durum wheat, genetic background, genetic markers, grain quality, phenotypic variation, quantitative trait loci, seed dormancy, seed germination, single nucleotide polymorphism, sprouting, substitution lines, tetraploidy
Durum wheat cultivars can benefit from having some level of seed dormancy to help reduce seed damage and lower grain quality caused by pre-harvest sprouting (PHS) occurring during wet harvesting conditions. Previously a single chromosome substitution line carrying chromosome 2B of wild emmer in the durum cultivar ‘Langdon’ background was found to have higher levels of seed dormancy and PHS tolerance. In this study, a population of recombinant substitution lines was developed and used to construct a SNP-based high density genetic linkage map. Seed germination tests were used to evaluate seed dormancy levels of the population grown in five field environments. Multiple interval mapping analysis revealed six QTL regions affecting seed dormancy. Two regions containing major-effect QTL contributed by wild emmer were consistently expressed in four environments and explained 5.89 to 11.14% of the phenotypic variation. One QTL region was located near the centromere and the other on the long arm of chromosome 2B in Bayes credible intervals of 4 and 7 cM, respectively. The two QTL regions identified in this study should be useful for improving PHS tolerance in wheat. Efforts to transfer the two QTL into elite durum cultivars are in progress to examine the effects of genetic background and environment on QTL expression and to evaluate the performance of other agronomic traits in the presence of the QTL.