title: High-resolution mapping of the Alp locus and identification of a candidate gene HvMATE controlling aluminium tolerance in barley (Hordeum vulgare L.).
abstract: Aluminium (Al) tolerance in barley is conditioned by the Alp locus on the long arm of chromosome 4H, which is associated with Al-activated release of citrate from roots. We developed a high-resolution map of the Alp locus using 132 doubled haploid (DH) lines from a cross between Dayton (Al-tolerant) and Zhepi 2 (Al-sensitive) and 2,070 F(2 )individuals from a cross between Dayton and Gairdner (Al-sensitive). The Al-activated efflux of citrate from the root apices of Al-tolerant Dayton was 10-fold greater than from the Al-sensitive parents Zhepi 2 and Gairdner. A suite of markers (ABG715, Bmag353, GBM1071, GWM165, HvMATE and HvGABP) exhibited complete linkage with the Alp locus in the DH population accounting 72% of the variation for Al tolerance evaluated as relative root elongation. These markers were used to map this genomic region in the Dayton/Gairdner population in more detail. Flanking markers HvGABP and ABG715 delineated the Alp locus to a 0.2 cM interval. Since the HvMATE marker was not polymorphic in the Dayton/Gairdner population we instead investigated the expression of the HvMATE gene. Relative expression of the HvMATE gene was 30-fold greater in Dayton than Gardiner. Furthermore, HvMATE expression in the F(2:3) families tested, including all the informative recombinant lines identified between HvGABP and ABG715 was significantly correlated with Al tolerance and Al-activated citrate efflux. These results identify HvMATE, a gene encoding a multidrug and toxic compound extrusion protein, as a candidate controlling Al tolerance in barley.
authors.affiliation: Tasmanian Institute of Agricultural Research and School of Agricultural Science, University of Tasmania, P.O. Box 46, Kings Meadows, TAS, 6249, Australia.
authors.forename: Junping
authors.initials: J
authors.lastname: Wang
authors.forename: Harsh
authors.initials: H
authors.lastname: Raman
authors.forename: Meixue
authors.initials: M
authors.lastname: Zhou
authors.forename: Peter R
authors.initials: PR
authors.lastname: Ryan
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Delhaize
authors.forename: Diane M
authors.initials: DM
authors.lastname: Hebb
authors.forename: Neil
authors.initials: N
authors.lastname: Coombes
authors.forename: Neville
authors.initials: N
authors.lastname: Mendham
mesh_terms: D000535:Aluminum / Q000378:metabolism*; D002874:Chromosome Mapping; D019343:Citric Acid / Q000378:metabolism; D005819:Genetic Markers; D018745:Genome, Plant; D001467:Hordeum / Q000235:genetics* / Q000378:metabolism; D012275:Oryza / Q000235:genetics; D010940:Plant Proteins / Q000235:genetics* / Q000502:physiology; D020641:Polymorphism, Single Nucleotide; D012434:Secale / Q000235:genetics; D026801:Synteny; D014908:Triticum / Q000235:genetics
chemical_list: D005819:Genetic Markers; D010940:Plant Proteins; D019343:Citric Acid; D000535:Aluminum