Assessing diversity in Triticum durum cultivars and breeding lines for high versus low cadmium content in seeds using the CAPS marker usw47

Cadmium (Cd) is a toxic heavy metal that occurs naturally in soils. Durum wheat is known to accumulate generally more Cd than other cereal crops. The uptake of Cd in durum wheat is governed by the gene Cdu1, which co-segregates with several DNA markers, such as the co-dominant marker usw47 and the dominant marker ScOPC20. A panel of 314 durum wheat cultivars or lines originating from 16 countries or regions were assessed with usw47. The plant material was mainly comprised of cultivars and modern breeding lines. From this set, 165 durum wheat lines were classified as low-Cd accumulators, 144 high-Cd accumulators and five were heterogeneous. A smaller subset of 16 cultivars had previously been evaluated for Cd accumulation in replicated field trials. Lines with the high-Cd allele showed a 2.4-fold higher Cd content in the seeds than lines with the low-Cd allele. We also compared the utility of markers usw47 and ScOPC20 as selection tools. Marker-assisted selection appears as a robust and practicable tool for breeding durum cultivars with low-Cd content.