Abstract
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.
Highlights
Plant breeding has been very successful at increasing the frequency of beneficial alleles for yield at many loci [1]
The diversity panel of durum wheat landraces was genotyped with the DArTSeq platform (Diversity Array Technology Pty Ltd., DArT P/L, Canberra, Australia)
The co-localization of the marker-trait associations (MTAs) identified in this work with those of previous studies in both durum and bread wheat confirms the importance of these markers in relation to stem traits
Summary
Plant breeding has been very successful at increasing the frequency of beneficial alleles for yield at many loci [1]. Modern breeding keeps making crosses between closely related high-yielding varieties, but many beneficial alleles have undoubtedly been left behind due to the bottlenecks of domestication coupled with modern breeding [1]. This is a serious problem considering the current scenario of climate change. The increasing risk of heat stress is expected to result in substantial yield losses. Both chronic increases in temperature and transient hot days are already producing large decreases in yield in Australia (reviewed by Passioura et al [2])
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