Abscisic Acid Accumulation in Developing Seeds of Phaseolus vulgaris L

Abstract

Free and bound abscisic acid (ABA) in the pod, seed coat and embryo were determined separately throughout seed development of P. vulgaris L. cv. ''Taylor''s Horticultural.'' An internal standard method of GLC was used for ABA quantification. In the embryo, 2 peaks of free ABA occurred at days 22 (1.8 M/g or 5.5 MM) and 28 (1.74 M/g or 12 MM); and a single peak of bound ABA at day 30. In the seed coat, there was 1 peak of free ABA at day 22 and only small amounts of bound ABA. Very small amounts of ABA were detected in the pod at any stage of development. In cv. PI 226895, in which seed development is more rapid than in ''Taylor''s Horticultural,'' the embryo ABA peaks occur on day 20 and 26. The timing of the ABA peak in the embryo and the concentration attained, are consistent with previous reports on the natural pattern of RNA synthesis and with ABA inhibition of RNA synthesis in developing bean fruit.