Genome-Wide Association Analysis for Stem Cross Section Properties, Height and Heading Date in a Collection of...

Durum wheat landraces have a high potential for breeding but they remain underexploited due to several factors, including the insufficient evaluation of these plant materials and the lack of efficient selection tools for transferring target traits into elite backgrounds. In this work, we characterized 150 accessions of the Spanish durum wheat collection for stem cross section, height and heading date. Continuous variation and high heritabilities were recorded for the stem area, pith area, pith diameter, culm wall thickness, height and heading date. The accessions were genotyped with DArTSeq markers, which were aligned to the durum wheat 'Svevo' genome. The markers corresponding to genes, with a minor allele frequency above 5% and less than 10% of missing data, were used for genome-wide association scan analysis. Twenty-nine marker-trait associations (MTAs) were identified and compared with the positions of previously known QTLs. MTAs for height and heading date co-localized with the QTLs for these traits. In addition, all the MTAs for stem traits in chromosome 2B were located in the corresponding synteny regions of the markers associated with lodging in bread wheat. Finally, several MTAs for stem traits co-located with the QTL for wheat stem sawfly (WSS) resistance. The results presented herein reveal the same genomic regions in chromosome 2B are involved in the genetic control of stem traits and lodging tolerance in both durum and bread wheat. In addition, these results suggest the importance of stem traits for WSS resistance and the potential of these landraces as donors for lodging tolerance and WSS resistance enhancement. In this context, the MTAs for stem-related traits identified in this work can serve as a reference for further development of markers for the introgression of target traits into elite material.