Abstract
Although the nuclear RNA binding protein FCA and the Mg-chelatase H subunit localized in the chloroplast have recently been reported as receptors for the plant hormone, abscisic acid (ABA), some physiological evidence suggest perception of the ABA signal on the cell surface. By using biotinylated ABA, we visualized and quantitatively characterized the putative ABA perception sites on the cell surface of Vicia faba guard cell protoplasts and barley aleurone protoplasts (Yamazaki et al., 2003; Kitahata et al., 2005). In the present study, in an attempt to identify putative plasma membrane ABA receptors, we applied the phage display technique using the cDNA library from Arabidopsis thaliana to screen for novel biotinlylated ABA-binding proteins. Subcellular localization, ABA sensitivity of the T-DNA insertional mutants in terms of seed germination, root growth and stomatal closure, as well as the ABA binding activity of the putative novel ABA binding proteins will be discussed.
