RRC ID 4620
Author Furukawa J, Yamaji N, Wang H, Mitani N, Murata Y, Sato K, Katsuhara M, Takeda K, Ma JF.
Title An aluminum-activated citrate transporter in barley.
Journal Plant Cell Physiol.
Abstract Soluble ionic aluminum (Al) inhibits root growth and reduces crop production on acid soils. Al-resistant cultivars of barley (Hordeum vulgare L.) detoxify Al by secreting citrate from the roots, but the responsible gene has not been identified yet. Here, we identified a gene (HvAACT1) responsible for the Al-activated citrate secretion by fine mapping combined with microarray analysis, using an Al-resistant cultivar, Murasakimochi, and an Al-sensitive cultivar, Morex. This gene belongs to the multidrug and toxic compound extrusion (MATE) family and was constitutively expressed mainly in the roots of the Al-resistant barley cultivar. Heterologous expression of HvAACT1 in Xenopus oocytes showed efflux activity for (14)C-labeled citrate, but not for malate. Two-electrode voltage clamp analysis also showed transport activity of citrate in the HvAACT1-expressing oocytes in the presence of Al. Overexpression of this gene in tobacco enhanced citrate secretion and Al resistance compared with the wild-type plants. Transiently expressed green fluorescent protein-tagged HvAACT1 was localized at the plasma membrane of the onion epidermal cells, and immunostaining showed that HvAACT1 was localized in the epidermal cells of the barley root tips. A good correlation was found between the expression of HvAACT1 and citrate secretion in 10 barley cultivars differing in Al resistance. Taken together, our results demonstrate that HvAACT1 is an Al-activated citrate transporter responsible for Al resistance in barley.
Volume 48(8)
Pages 1081-91
Published 2007-8
DOI 10.1093/pcp/pcm091
PII pcm091
PMID 17634181
MeSH Aluminum / pharmacology* Animals Carrier Proteins / genetics Carrier Proteins / metabolism Carrier Proteins / physiology* Citric Acid / metabolism Cloning, Molecular Female Gene Expression Regulation, Plant / drug effects Green Fluorescent Proteins / genetics Green Fluorescent Proteins / metabolism Hordeum / classification Hordeum / genetics Hordeum / metabolism* In Situ Hybridization Malates / metabolism Membrane Potentials / genetics Membrane Potentials / physiology Molecular Sequence Data Oligonucleotide Array Sequence Analysis Onions / genetics Onions / metabolism Phylogeny Plant Proteins / genetics Plant Proteins / metabolism Plant Proteins / physiology* Plant Roots / genetics Plant Roots / metabolism Plants, Genetically Modified Recombinant Fusion Proteins / genetics Recombinant Fusion Proteins / metabolism Sequence Analysis, DNA Tobacco / genetics Tobacco / metabolism Xenopus laevis
IF 3.929
Times Cited 202
Barley EST clones