Dissecting the QTLome Governing Root System Architecture Features in Durum Wheat

Linkage (biparental) and association mapping were used for the dissection of the QTLome governing root system architecture (RSA) in seedlings of two recombinant inbred line populations and one association mapping panel of 183 elite durum wheat (Triticum turgidum L. var. durum Desf.), respectively. In total, 20 clusters of QTLs for root length and/or number as well as 30 QTLs for root growth angle (RGA) were evidenced. QTLs were mapped on a high-density tetraploid consensus map based on a transcript-associated Illumina 90K SNP assay developed for bread and durum wheat, thus allowing for an accurate cross-referencing of RSA QTLs between tetraploid and hexaploid wheat. Among the main QTL clusters for root length and number highlighted in this study, 15 overlapped with QTLs for multiple RSA traits reported also in bread wheat while out of 30 QTLs for RGA, only six colocated with QTLs previously reported in wheat. Based on their relative additive effects, allelic distribution in the AM panel and co-location with QTLs for yield and kernel weight, the RSA QTLs have been prioritized in terms of breeding value. Three major QTL clusters for root length and number and five QTLs for RGA appear particularly suitable for a possible deployment in marker-assisted selection and positional cloning.