title: Prioritizing quantitative trait loci for root system architecture in tetraploid wheat.
abstract: Optimization of root system architecture (RSA) traits is an important objective for modern wheat breeding. Linkage and association mapping for RSA in two recombinant inbred line populations and one association mapping panel of 183 elite durum wheat (Triticum turgidum L. var. durum Desf.) accessions evaluated as seedlings grown on filter paper/polycarbonate screening plates revealed 20 clusters of quantitative trait loci (QTLs) for root length and number, as well as 30 QTLs for root growth angle (RGA). Divergent RGA phenotypes observed by seminal root screening were validated by root phenotyping of field-grown adult plants. QTLs were mapped on a high-density tetraploid consensus map based on transcript-associated Illumina 90K single nucleotide polymorphisms (SNPs) developed for bread and durum wheat, thus allowing for an accurate cross-referencing of RSA QTLs between durum and bread wheat. Among the main QTL clusters for root length and number highlighted in this study, 15 overlapped with QTLs for multiple RSA traits reported in bread wheat, while out of 30 QTLs for RGA, only six showed co-location with previously reported QTLs in wheat. Based on their relative additive effects/significance, allelic distribution in the association mapping panel, and co-location with QTLs for grain weight and grain yield, the RSA QTLs have been prioritized in terms of breeding value. Three major QTL clusters for root length and number (RSA_QTL_cluster_5#, RSA_QTL_cluster_6#, and RSA_QTL_cluster_12#) and nine RGA QTL clusters (QRGA.ubo-2A.1, QRGA.ubo-2A.3, QRGA.ubo-2B.2/2B.3, QRGA.ubo-4B.4, QRGA.ubo-6A.1, QRGA.ubo-6A.2, QRGA.ubo-7A.1, QRGA.ubo-7A.2, and QRGA.ubo-7B) appear particularly valuable for further characterization towards a possible implementation of breeding applications in marker-assisted selection and/or cloning of the causal genes underlying the QTLs.
authors.affiliation: Department of Agricultural Sciences (DipSA), University of Bologna, 40127 Bologna, Italy marco.maccaferri@unibo.it.
authors.forename: Marco
authors.initials: M
authors.lastname: Maccaferri
authors.affiliation: Department of Agricultural Sciences (DipSA), University of Bologna, 40127 Bologna, Italy Department of Crop Sciences, Faculty of Agriculture, Alexandria University, 23714 Alexandria, Egypt.
authors.forename: Walid
authors.initials: W
authors.lastname: El-Feki
authors.affiliation: Department of Agricultural Sciences (DipSA), University of Bologna, 40127 Bologna, Italy Department of Agriculture, Hajiabad Branch, Islamic Azad University, 21100 Hajiabad, Iran.
authors.forename: Ghasemali
authors.initials: G
authors.lastname: Nazemi
authors.affiliation: Department of Agricultural Sciences (DipSA), University of Bologna, 40127 Bologna, Italy.
authors.forename: Silvio
authors.initials: S
authors.lastname: Salvi
authors.affiliation: Department of Agricultural Sciences (DipSA), University of Bologna, 40127 Bologna, Italy.
authors.forename: Maria Angela
authors.initials: MA
authors.lastname: Canè
authors.affiliation: Department of Agricultural Sciences (DipSA), University of Bologna, 40127 Bologna, Italy.
authors.forename: Maria Chiara
authors.initials: MC
authors.lastname: Colalongo
authors.affiliation: Department of Agricultural Sciences (DipSA), University of Bologna, 40127 Bologna, Italy.
authors.forename: Sandra
authors.initials: S
authors.lastname: Stefanelli
authors.affiliation: Department of Agricultural Sciences (DipSA), University of Bologna, 40127 Bologna, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Tuberosa
mesh_terms: D002874:Chromosome Mapping; D032461:Chromosomes, Plant; D056726:Genetic Association Studies; D008040:Genetic Linkage; D018517:Plant Roots / Q000033:anatomy & histology / Q000235:genetics* / Q000254:growth & development; D040641:Quantitative Trait Loci; D057891:Tetraploidy; D014908:Triticum / Q000033:anatomy & histology / Q000235:genetics* / Q000254:growth & development
keywords: Association mapping; GWAS; drought stress; germplasm collection; grain yield; meta-QTLs; root growth angle; root system architecture; rooting depth; seminal root.