CHANGES IN ABSCISIC-ACID AND ITS BETA-D-GLUCOPYRANOSYL ESTER LEVELS DURING TOMATO (LYCOPERSICON-ESCULENTUM MILL) SEED DEVELOPMENT

The role of abscisic acid (ABA) in tomato (Lycopersicon esculentum Mill.) zygotic embryogenesis was analysed. ABA and ABA beta-D-glucopyranosyl ester (ABA-GE) changes were determined in seeds and fruit tissues - placenta and mesocarp - during seed development, which was defined with eight embryo stages: from globular (stage 1) to mature embryo (stage 8). In whole seeds, ABA changes paralleled fresh and dry weight pattern curves and could be characterized by a high increase during embryo growth followed by a decrease as the seed matured and dehydrated. Moreover this dehydration phase led, at stage 8, to a new ABA distribution within the seed, preferentially into integument and embryo. Fruit tissue analyses provided new information about the ABA origin in seeds. ABA-GE levels were also measured and the results suggested different ABA metabolism in seed and fruit tissues.