Abscisic acid promotes lectin biosynthesis in developing and germinating rice embryos.

Immature rice (Oryza sativa, L) embryos isolated about 12 days post anthesis are fully able to develop into young seedlings when cultured in vitro. Concomitantly, they rapidly loose their lectin synthesis activity. Abscisic acid added to the nutrient medium prevents precocious germination of the immature embryos and simultaneously strongly promotes lectin biosynthesis activity. Similarly, abscisic acid keeps mature embryos grown in a nutrient medium in a dormant state and maintains their lectin synthesis activity, whereas control embryos rapidly germinate but also quickly loose their lectin synthesis activity. It appears, therefore, that rice lectin is typically synthesized in embryos which are kept in a dornant state.