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Genome-Wide Association Mapping of Leaf Rust Response in a Durum Wheat Worldwide Germplasm Collection

Aoun, Meriem, Breiland, Matthew, Turner, M. Kathryn, Loladze, Alexander, Chao, Shiaoman, Xu, Steven S., Ammar, Karim, Anderson, James A., Kolmer, James A., Acevedo, Maricelis
The Plant Genome 2016 v.9 no.3
Puccinia recondita, Triticum turgidum subsp. durum, adults, breeding lines, chromosome mapping, crop production, cultivars, disease resistance, durum wheat, field experimentation, genetic markers, genome-wide association study, germplasm, landraces, leaf rust, loci, mature plants, races, seedlings, single nucleotide polymorphism, virulence, Great Plains region, Kansas, Mexico
Leaf rust (caused by Puccinia triticina Eriks.) is increasingly impacting durum wheat production with the recent appearance of races with virulence to widely grown cultivars in many durum producing areas worldwide. A highly virulent P. triticina race on durum wheat was recently collected in Kansas. This race may spread to Northern Great Plains, where most of the U.S. durum wheat is produced. The objective of this study was to identify sources of resistance to several races from USA and Mexico at seedling stage in the greenhouse and at adult stage in field experiments. Genome wide association analysis was used to identify SNP markers associated with leaf rust response in a worldwide durum wheat collection of 496 accessions. Ten accessions comprised of six landraces, two breeding lines, and two cultivars were resistant across all experiments. Association mapping revealed 88 significant SNPs, associated with leaf rust response. Of these 88 SNPs, 33 were located on chromosomes 2A and 2B, and 55 were distributed across all other chromosomes except for 1B and 7B. Twenty markers were associated with leaf rust response at seedling stage, while 68 markers were associated with leaf rust response at adult plant stage. The current study identified a total of 20 previously uncharacterized loci associated with leaf rust response in durum wheat. The discovery of these loci through association mapping is a significant step in identifying useful sources of resistance that can be used to broaden relatively narrow leaf rust resistance spectrum in durum wheat germplasm.