Abscisic acid levels and metabolism in the leaf epidermal tissue of Tulipa gesneriana L. and Commelina communis L.

Abstract
We have shown the presence of abscisic acid (ABA) in abaxial epidermal strips taken from Tulipa gesneriana and Commelina communis and that the ABA level rises in the epidermis when leaves are water stressed. ABA levels had risen 50% in the abaxial epidermis of C. communis 30 min after the leaves lost 10% of their fresh weight. Epidermis from both T. gesneriana and C. communis metabolize [14C]ABA to several products probably including phaseic acid (PA) and dihydrophaseic acid (DPA).