A plant enzyme - vellosimine reductase - has been isolated from Rauwolfia cell suspension cultures. This new enzyme has been-purified (110-fold) and characterized. The reductase is a specificenzyme of the sarpagine pathway catalyzing the NADPH dependent conversion of vellosimine into 10-deoxysarpagine. The latter alkaloid is the immediate biogenetic precursor of sarpagine as shown by its high in vivo