XVI International Botanical Congess

The ATP-binding cassette (ABC) superfamily is probably the largest family of proteins that mediate ATP-dependent transfer of solutes. Among ABC transporters identified in animal cells, it has emerged that some of them bind sulfonylureas and exhibit an ion channel activity. We have investigated the role of an ABC protein in guard cells and its involvement in the control of ion channels. We demonstrate the existence of a sulfonylurea-receptor-like protein involved in the outward potassium channel regulation during stomatal movements (Leonhardt et al., 1997, PNAS 94: 14156-161). Moreover, sulfonylureas dramatically affect the Ca2+-induced stomatal closure and the ABA-stimulated anion currents (Leonhardt et al., 1999, Plant Cell, In press). Elements concerning a more detailed identification of this receptor and its interaction with the ABA-signaling cascade will be presented at the meeting.