STUDIES OF PHLORIDZIN IN MALUS

Abstract

The phloridzin content of dormant terminal twigs of Malus root-stock clones was not related to the vigor imparted to the scions. In young seedling trees it varied with the nutritional status of the plant; an acute deficiency of N, S, or Ca resulted in a significant increase in phloridzin accumulation. Phloridzin is synthesized readily in the leaf from C14O2 in the light and appears to be stable once formed. Phenylalanine-C and tyrosine-C , when fed to leaf disks, are incorporated into the Cg-C, moiety of phloridzin which includes ring B. Tyrosine is not as effective as phenylalanine. Acetate-C14 is incorporated into ring A. Phloroglucinol is not involved in the synthesis of phloridzin. A method for the quantitative determination of phloridzin is described, also a semimicro method for its alkaline hydrolysis. The large amounts of radioactive d-glucitol formed from a wide variety of precursor compounds indicate a central role for it in the carbohydrate metabolism of Malus.