title: Association mapping for root architectural traits in durum wheat seedlings as related to agronomic performance.
abstract: Association mapping provides useful insights on the genetic architecture of quantitative traits across a large number of unrelated genotypes, which in turn allows an informed choice of the lines to be crossed for a more accurate characterization of major QTLs in a biparental genetic background. In this study, seedlings of 183 durum wheat elite accessions were evaluated in order to identify QTLs for root system architecture (RSA). The QTLs identified were compared with QTLs detected for grain yield and its component traits, plant height and peduncle length measured in a previous study where the same accessions were evaluated in 15 field trials with a broad range of soil moisture availability and productivity (Maccaferri et al. in J Exp Bot 62:409-438, 2011). The following RSA features were investigated in seedlings at the four-leaf stage: seminal root angle, primary root length, total root length, average root length, root number and shoot length. Highly significant differences among accessions were detected for all traits. The highest repeatability (h2= 0.72) was observed for seminal root angle. Out of the 48 QTLs detected for RSA, 15 overlapped with QTLs for agronomic traits and/or grain yield in two or more environments. The congruency of the effects of RSA traits and agronomic traits was evaluated. Seminal root angle and root number appear the most promising traits for further studies on the adaptive role of RSA plasticity on field performance in environments differing for water availability. Our results provide novel insights on the genetic control of RSA and its implications on field performance of durum wheat.
authors.affiliation: Department of Agricultural Sciences (DipSA), University of Bologna, Viale Fanin 44, 40127 Bologna, Italy.
authors.forename: Maria Angela
authors.initials: MA
authors.lastname: Canè
authors.affiliation: Department of Agricultural Sciences (DipSA), University of Bologna, Viale Fanin 44, 40127 Bologna, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Maccaferri
authors.affiliation: Department of Agricultural Sciences (DipSA), University of Bologna, Viale Fanin 44, 40127 Bologna, Italy ; Department of Plant Production, I.A.U. Haji abad Branch, Haji abad, Iran.
authors.forename: Ghasemali
authors.initials: G
authors.lastname: Nazemi
authors.affiliation: Department of Agricultural Sciences (DipSA), University of Bologna, Viale Fanin 44, 40127 Bologna, Italy.
authors.forename: Silvio
authors.initials: S
authors.lastname: Salvi
authors.affiliation: Department of Agricultural Sciences (DipSA), University of Bologna, Viale Fanin 44, 40127 Bologna, Italy.
authors.forename: Rossella
authors.initials: R
authors.lastname: Francia
authors.affiliation: Department of Agricultural Sciences (DipSA), University of Bologna, Viale Fanin 44, 40127 Bologna, Italy.
authors.forename: Chiara
authors.initials: C
authors.lastname: Colalongo
authors.affiliation: Department of Agricultural Sciences (DipSA), University of Bologna, Viale Fanin 44, 40127 Bologna, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Tuberosa
keywords: Agronomic performance; Association mapping; Drought; QTL; Root architecture; Root number; Seminal root angle; Triticum turgidum L. subsp. durum (Desf.) Husn.; Yield