ABC transporter AtABCG25 is involved in abscisic acid transport and responses

Abstract

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 ABAproducing 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 ATPdependent 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.Arabidopsis | ABCG | transposon-tagged lines

Environmental nitrate signals through abscisic acid in the root tip

“…Recently, several ABA transporters have been identified, many of which also transport other substrates. 19,[47][48][49][50] Increasing the concentration of one substrate is likely to have effects on the transport of the others. For AtNPF4.1, transport of the gibberellin, GA 3 , competes with ABA transport.…”

A petunia ABC protein controls strigolactone-dependent symbiotic signalling and branching

“…Despite their importance, it is not known how strigolactones are transported. ATP-binding cassette (ABC) transporters, however, are known to have functions in phytohormone translocation [7][8][9] . Here we show that the Petunia hybrida ABC transporter PDR1 has a key role in regulating the development of arbuscular mycorrhizae and axillary branches, by functioning as a cellular strigolactone exporter.…”

“…The rationale behind the focus on these transporters, of which there are 15 in Arabidopsis 11 , 23 in Oryza sativa (rice) 11 and 23 putative factors in Solanum lycopersicum (tomato) ( Supplementary Fig. 3a), was that they are plasma membrane proteins often found in roots 12 , they are implicated in below-ground plantmicrobe interactions 13,14 , and they have affinities for compounds that are structurally related to strigolactones 8,9,15 . Of six primary candidates, only P. hybrida PDR1 had increased expression in roots that were subjected to either phosphate starvation (Fig.…”

Arabidopsis ABCG14 protein controls the acropetal translocation of root-synthesized cytokinins

“…ABC subfamily G (ABCG) includes 28 members of the white-brown complex half transporters, and 15 pleiotropic drug resistance full transporters 16 . Several members of this subfamily have demonstrated responsibility for exporting wax and cutin used in the formation of cuticle in aerial organs 18 , for conveying abscisic acid across the plasma membrane in leaf guard cells 19 and for exporting auxinic compounds, including indole-3-butyric acid 20 . Seemingly, the ABCG subfamily proteins participate in various biological processes.…”