Abstract
Yieldin (YLD) is a wall protein regulating the yield threshold (Y) under acidic condition. We have presumed that YLD interact with some wall-constituting molecules and tried to isolate the Yieldin-Associated Molecule (YAM).
The YAM isolated from the non-cellulosic cowpea wall polysaccharides using the YLD-bound affinity chromatography was about 120 kD and comprised of Xyl, Glc, Man and Gal in a ratio of 5-6:3-4:1:8-10. Its binding activity to YLD was stronger in acidic buffer than in a neutral one, since the amount of YAM bound to 1μg-YLD was 245μg of YAM under pH 4, but less than 1/10 under pH 6. The reconstruction experiments using the glycerinated hollow cylinder of cowpea hypocotyl pre-treated with YAM indicated that the YAM-treatment with over 100μg/mL YAM perfectly suppressed y-shift, and suggested that the YAM may play a key part in the Y-control mechanism by YLD.
