Subcellular Localization of 2-(beta-d-Glucosyloxy)-Cinnamic Acids and the Related beta-glucosidase in Leaves of Melilotus alba Desr

The distribution of the glucosides of trans- and cis-2-hydroxy cinnamic acid and of the β-glucosidase which hydrolyzes the latter glucoside was examined in preparations of epidermal and mesophyll tissue obtained from leaves of sweet clover (Melilotus alba Desr.). The concentrations of glucosides in the two tissues were about equal when compared on the basis of fresh or dry weight. Inasmuch as the epidermal layers account for no more than 10% of the leaf volume, the mesophyll tissue contains 90% or more of the glucosides. Vacuoles isolated from mesophyll protoplasts contained all of the glucosides present initially in the protoplasts.