title: Molecular mapping of a gene responsible for Al-activated secretion of citrate in barley.
abstract: Aluminium (Al) toxicity is an important limitation to barley (Hordeum vulgare L.) on acid soil. Al-resistant cultivars of barley detoxify Al externally by secreting citrate from the roots. To link the genetics and physiology of Al resistance in barley, genes controlling Al resistance and Al-activated secretion of citrate were mapped. An analysis of Al-induced root growth inhibition from 100 F2 seedlings derived from an Al-resistant cultivar (Murasakimochi) and an Al-sensitive cultivar (Morex) showed that a gene associated with Al resistance is localized on chromosome 4H, tightly linked to microsatellite marker Bmag353. Quantitative trait locus (QTL) analysis from 59 F4 seedlings derived from an F3 plant heterozygous at the region of Al resistance on chromosome 4H showed that a gene responsible for the Al-activated secretion of citrate was also tightly linked to microsatellite marker Bmag353. This QTL explained more than 50% of the phenotypic variation in citrate secretion in this population. These results indicate that the gene controlling Al resistance on barley chromosome 4H is identical to that for Al-activated secretion of citrate and that the secretion of citrate is one of the mechanisms of Al resistance in barley. The identification of the microsatellite marker associated with both Al resistance and citrate secretion provides a valuable tool for marker-assisted selection of Al-resistant lines.
authors.affiliation: Faculty of Agriculture, Kagawa University, Ikenobe 2393, Miki-cho, Kita-gun, Kagawa 761-0795, Japan. maj@ag.kagawa-u.ac.jp
authors.forename: Jian Feng
authors.initials: JF
authors.lastname: Ma
authors.forename: Sakiko
authors.initials: S
authors.lastname: Nagao
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Sato
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Ito
authors.forename: Jun
authors.initials: J
authors.lastname: Furukawa
authors.forename: Kazuyoshi
authors.initials: K
authors.lastname: Takeda
mesh_terms: D000222:Adaptation, Physiological / Q000187:drug effects*; D000535:Aluminum / Q000378:metabolism / Q000633:toxicity*; D002874:Chromosome Mapping / Q000379:methods; D019343:Citric Acid / Q000378:metabolism*; D001467:Hordeum / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D018517:Plant Roots / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D040641:Quantitative Trait Loci
chemical_list: D019343:Citric Acid; D000535:Aluminum