title: Brassinosteroid leaf unrolling QTL mapping in durum wheat.
abstract: Brassinosteroids are a newly reported class of plant growth phytohormones found in plants throughout the plant kingdom. Functioning at very low concentrations, they play an essential role in improving biomass yield and stress tolerance. There are no reports in the literature of the genetic variability of responsiveness of brassinosteroids in wheat; most studies on brassinosteroids have focused on the physiological effects of exogenous addition of brassinosteroids. Our aim was to study the genetic variation in the responsiveness of a doubled haploid durum wheat population to three brassinosteroid concentrations using the leaf unrolling test, which is a simple bioassay to test brassinosteroid activity. An F(1)-derived doubled haploid population of 77 individuals from the cross Strongfield/Blackbird was used to construct a genetic map of 427 molecular marker loci. The leaf unrolling test was performed on the parents and doubled haploid genotypes of the population using 0.2, 2 and 20 nM brassinosteroid concentrations. The results indicated significant differences in leaf unrolling between the two parents, doubled haploid genotypes, treatments and genotype-by-treatment combinations. Transgressive segregation beyond Strongfield of leaf unrolling was observed for all concentrations, with the strongest response at 20 nM. Putative quantitative trait loci were revealed in the intervals Xgwm2-Xbarc45 on chromosome 3A and Xwmc643a-Xwmc625a on chromosome 3B. Additional quantitative trait loci were associated with markers Xwmc48a, Xwmc511, Xwmc89a and Xgwmc692 on chromosome 4B, and Xwmc17 on chromosome 7A. This work should enhance the understanding of the relationship between stress tolerance and productivity, and responsiveness to brassinosteroids.
authors.affiliation: Semiarid Prairie Agriculture Research Centre, Agriculture and Agri-Food Canada (AAFC), Swift Current, SK, S9H 3X2, Canada.
authors.forename: Julio
authors.initials: J
authors.lastname: Isidro
authors.forename: Ron
authors.initials: R
authors.lastname: Knox
authors.forename: Asheesh
authors.initials: A
authors.lastname: Singh
authors.forename: Fran
authors.initials: F
authors.lastname: Clarke
authors.forename: Priti
authors.initials: P
authors.lastname: Krishna
authors.forename: Ron
authors.initials: R
authors.lastname: DePauw
authors.forename: John
authors.initials: J
authors.lastname: Clarke
authors.forename: Daryl
authors.initials: D
authors.lastname: Somers
mesh_terms: D060406:Brassinosteroids / Q000008:administration & dosage* / Q000378:metabolism*; D002874:Chromosome Mapping; D005819:Genetic Markers; D014644:Genetic Variation; D005838:Genotype; D006238:Haploidy; D018515:Plant Leaves / Q000254:growth & development*; D040641:Quantitative Trait Loci; D014908:Triticum / Q000235:genetics* / Q000378:metabolism*
chemical_list: D060406:Brassinosteroids; D005819:Genetic Markers