ABC transporter AtABCG25 is involved in abscisic acid transport and responses.
Abscisic acid (ABA) is one of the most important phytohormones involved in abiotic stress responses, seed maturation, germination, and senescence. ABA is predominantly produced in vascular tissues and exerts hormonal responses in various cells, including guard cells. Although ABA responses require extrusion of ABA from ABA-producing cells in an intercellular ABA signaling pathway, the transport mechanisms of ABA through the plasma membrane remain unknown. Here we isolated an ATP-binding cassette (ABC) transporter gene, AtABCG25, from Arabidopsis by genetically screening for ABA sensitivity. AtABCG25 was expressed mainly in vascular tissues. The fluorescent protein-fused AtABCG25 was localized at the plasma membrane in plant cells. In membrane vesicles derived from AtABCG25-expressing insect cells, AtABCG25 exhibited ATP-dependent ABA transport. The AtABCG25-overexpressing plants showed higher leaf temperatures, implying an influence on stomatal regulation. These results strongly suggest that AtABCG25 is an exporter of ABA and is involved in the intercellular ABA signaling pathway. The presence of the ABA transport mechanism sheds light on the active control of multicellular ABA responses to environmental stresses among plant cells.
Gene Discovery Research Group, RIKEN Plant Science Center, Yokohama 230-0045, Japan.
Takashi
T
Kuromori
Takaaki
T
Miyaji
Hikaru
H
Yabuuchi
Hidetada
H
Shimizu
Eriko
E
Sugimoto
Asako
A
Kamiya
Yoshinori
Y
Moriyama
Kazuo
K
Shinozaki
D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000378:metabolism*; D000040:Abscisic Acid / Q000378:metabolism*; D000818:Animals; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D017931:DNA Primers / Q000235:genetics; D015870:Gene Expression; D017343:Genes, Plant; D009154:Mutation; D010937:Plant Growth Regulators / Q000378:metabolism*; D030821:Plants, Genetically Modified; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D018411:Spodoptera; D014018:Tissue Distribution; D014162:Transfection
D018528:ATP-Binding Cassette Transporters; D029681:Arabidopsis Proteins; D017931:DNA Primers; D010937:Plant Growth Regulators; D011993:Recombinant Fusion Proteins; D000040:Abscisic Acid