RRC ID 52762
Author Takanashi K, Sasaki T, Kan T, Saida Y, Sugiyama A, Yamamoto Y, Yazaki K.
Title A Dicarboxylate Transporter, LjALMT4, Mainly Expressed in Nodules of Lotus japonicus.
Journal Mol. Plant Microbe Interact.
Abstract Legume plants can establish symbiosis with soil bacteria called rhizobia to obtain nitrogen as a nutrient directly from atmospheric N2 via symbiotic nitrogen fixation. Legumes and rhizobia form nodules, symbiotic organs in which fixed-nitrogen and photosynthetic products are exchanged between rhizobia and plant cells. The photosynthetic products supplied to rhizobia are thought to be dicarboxylates but little is known about the movement of dicarboxylates in the nodules. In terms of dicarboxylate transporters, an aluminum-activated malate transporter (ALMT) family is a strong candidate responsible for the membrane transport of carboxylates in nodules. Among the seven ALMT genes in the Lotus japonicus genome, only one, LjALMT4, shows a high expression in the nodules. LjALMT4 showed transport activity in a Xenopus oocyte system, with LjALMT4 mediating the efflux of dicarboxylates including malate, succinate, and fumarate, but not tricarboxylates such as citrate. LjALMT4 also mediated the influx of several inorganic anions. Organ-specific gene expression analysis showed LjALMT4 mRNA mainly in the parenchyma cells of nodule vascular bundles. These results suggest that LjALMT4 may not be involved in the direct supply of dicarboxylates to rhizobia in infected cells but is responsible for supplying malate as well as several anions necessary for symbiotic nitrogen fixation, via nodule vasculatures.
Volume 29(7)
Pages 584-92
Published 2016-7
DOI 10.1094/MPMI-04-16-0071-R
PMID 27183039
MeSH Dicarboxylic Acid Transporters / genetics* Dicarboxylic Acid Transporters / metabolism Genes, Reporter Loteae / cytology Loteae / genetics* Loteae / metabolism Molecular Sequence Data Nitrogen Fixation Phylogeny Plant Proteins / genetics Plant Proteins / metabolism Rhizobium / cytology Rhizobium / physiology* Root Nodules, Plant / cytology Root Nodules, Plant / metabolism Root Nodules, Plant / microbiology Sequence Analysis, DNA Symbiosis*
IF 3.649
Lotus / Glycine E023-H-12