Vacuolar localization of the enzymatic synthesis of hydroxycinnamic acid esters of malic acid in protoplasts from Raphanus sativus leaves

Protoplasts from leaves of radish ( Raphanus sativus L. var. sativus ) were examined for the subcellular localization of p -coumaric, caffeic, ferulic and sinapic acid esters of malic acid and the enzyme(s) involved in their syntheses. Vacuoles isolated from leaf protoplasts contained all the hydroxycinnamic acid esters as well as all the dependent enzyme activities. Protein from leaf vacuoles was shown to form the hydroxycinnamoylmalic acids, using the corresponding hydroxycinnamic acid glucose esters (1-O-acyl glucosides) as acyl donors. It is proposed that the vacuole is the cell compartment for synthesis and deposition of the hydroxycinnamoylmalic acids.