title: Two major quantitative trait loci controlling the number of seminal roots in maize co-map with the root developmental genes rtcs and rum1.
abstract: The genetic dissection of root architecture and functions allows for a more effective and informed design of novel root ideotypes and paves the way to evaluate their effects on crop resilience to a number of abiotic stresses. In maize, limited attention has been devoted to the genetic analysis of root architecture diversity at the early stage. The difference in embryonic (including seminal and primary) root architecture between the maize reference line B73 (which mostly develops three seminal roots) and the landrace Gaspé Flint (with virtually no seminal roots) was genetically dissected using a collection of introgression lines grown in paper rolls and pots. Quantitative trait locus (QTL) analysis identified three QTLs controlling seminal root number (SRN) on chromosome bins 1.02, 3.07, and 8.04-8.05, which collectively explained 66% of the phenotypic variation. In all three cases, Gaspé Flint contributed the allele for lower SRN. Primary root dry weight was negatively correlated with SRN (r= -0.52), and QTLs for primary root size co-mapped with SRN QTLs, suggesting a pleiotropic effect of SRN QTLs on the primary root, most probably caused by competition for seed resources. Interestingly, two out of three SRN QTLs co-mapped with the only two known maize genes (rtcs and rum1) affecting the number of seminal roots. The strong additive effect of the three QTLs and the development of near isogenic lines for each QTL in the elite B73 background provide unique opportunities to characterize functionally the genes involved in root development and to evaluate how root architecture affects seedling establishment, early development, and eventually yield in maize.
authors.affiliation: DipSA University of Bologna, viale Fanin 44, 40127 Bologna, Italy silvio.salvi@unibo.it.
authors.forename: Silvio
authors.initials: S
authors.lastname: Salvi
authors.affiliation: DipSA University of Bologna, viale Fanin 44, 40127 Bologna, Italy.
authors.forename: Silvia
authors.initials: S
authors.lastname: Giuliani
authors.affiliation: DipSA University of Bologna, viale Fanin 44, 40127 Bologna, Italy.
authors.forename: Claudia
authors.initials: C
authors.lastname: Ricciolini
authors.affiliation: DipSA University of Bologna, viale Fanin 44, 40127 Bologna, Italy.
authors.forename: Nicola
authors.initials: N
authors.lastname: Carraro
authors.affiliation: DipSA University of Bologna, viale Fanin 44, 40127 Bologna, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Maccaferri
authors.affiliation: KWS SAAT SE, Grimsehlstr. 31, D-37555 Einbeck, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Presterl
authors.affiliation: KWS SAAT SE, Grimsehlstr. 31, D-37555 Einbeck, Germany.
authors.forename: Milena
authors.initials: M
authors.lastname: Ouzunova
authors.affiliation: DipSA University of Bologna, viale Fanin 44, 40127 Bologna, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Tuberosa
mesh_terms: D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D018517:Plant Roots / Q000033:anatomy & histology / Q000196:embryology / Q000235:genetics* / Q000254:growth & development; D040641:Quantitative Trait Loci; D003313:Zea mays / Q000033:anatomy & histology / Q000196:embryology / Q000235:genetics* / Q000254:growth & development
chemical_list: D010940:Plant Proteins
keywords: Maize; QTL; primary root; root architecture; seminal roots; stress tolerance.