title: AtALMT1, which encodes a malate transporter, is identified as one of several genes critical for aluminum tolerance in Arabidopsis.
abstract: Aluminum (Al) tolerance in Arabidopsis is a genetically complex trait, yet it is mediated by a single physiological mechanism based on Al-activated root malate efflux. We investigated a possible molecular determinant for Al tolerance involving a homolog of the wheat Al-activated malate transporter, ALMT1. This gene, named AtALMT1 (At1g08430), was the best candidate from the 14-member AtALMT family to be involved with Al tolerance based on expression patterns and genomic location. Physiological analysis of a transferred DNA knockout mutant for AtALMT1 as well as electrophysiological examination of the protein expressed in Xenopus oocytes showed that AtALMT1 is critical for Arabidopsis Al tolerance and encodes the Al-activated root malate efflux transporter associated with tolerance. However, gene expression and sequence analysis of AtALMT1 alleles from tolerant Columbia (Col), sensitive Landsberg erecta (Ler), and other ecotypes that varied in Al tolerance suggested that variation observed at AtALMT1 is not correlated with the differences observed in Al tolerance among these ecotypes. Genetic complementation experiments indicated that the Ler allele of AtALMT1 is equally effective as the Col allele in conferring Al tolerance and Al-activated malate release. Finally, fine-scale mapping of a quantitative trait locus (QTL) for Al tolerance on chromosome 1 indicated that AtALMT1 is located proximal to this QTL. These results indicate that AtALMT1 is an essential factor for Al tolerance in Arabidopsis but does not represent the major Al tolerance QTL also found on chromosome 1.
authors.affiliation: Boyce Thompson Institute for Plant Research, Ithaca, NY 14853, USA.
authors.forename: Owen A
authors.initials: OA
authors.lastname: Hoekenga
authors.forename: Lyza G
authors.initials: LG
authors.lastname: Maron
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Piñeros
authors.forename: Geraldo M A
authors.initials: GM
authors.lastname: Cançado
authors.forename: Jon
authors.initials: J
authors.lastname: Shaff
authors.forename: Yuriko
authors.initials: Y
authors.lastname: Kobayashi
authors.forename: Peter R
authors.initials: PR
authors.lastname: Ryan
authors.forename: Bei
authors.initials: B
authors.lastname: Dong
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Delhaize
authors.forename: Takayuki
authors.initials: T
authors.lastname: Sasaki
authors.forename: Hideaki
authors.initials: H
authors.lastname: Matsumoto
authors.forename: Yoko
authors.initials: Y
authors.lastname: Yamamoto
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Koyama
authors.forename: Leon V
authors.initials: LV
authors.lastname: Kochian
mesh_terms: D000535:Aluminum / Q000494:pharmacology*; D000596:Amino Acids / Q000235:genetics / Q000378:metabolism; D017360:Arabidopsis / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D018744:DNA, Plant / Q000235:genetics; D004594:Electrophysiology; D017343:Genes, Plant / Q000235:genetics*; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D027361:Organic Anion Transporters / Q000235:genetics / Q000378:metabolism*; D018517:Plant Roots / Q000187:drug effects / Q000378:metabolism; D011110:Polymorphism, Genetic / Q000235:genetics
chemical_list: C512361:ALMT1 protein, Arabidopsis; D000596:Amino Acids; D029681:Arabidopsis Proteins; D018744:DNA, Plant; D027361:Organic Anion Transporters; D000535:Aluminum