Relationship of Phenylalanine Ammonia-lyase Activity to o-Hydroxycinnamic Acid Content in Melilotus alba

Authors

A. Kleinhofs, University of Nebraska-Lincoln
Francis A. Haskins, University of Nebraska-LincolnFollow
Herman J. Gorz, University of Nebraska-Lincoln

Date of this Version

8-1966

Comments

Published in Plant Physiology 41:8 (1966). pp. 1276–1279. Copyright © 1966 American Society of Plant Biologists.

Abstract

Phenylalanine ammonia-lyase activity was investigated in preparations representing various parts of sweetclover (Melilotus alba Desr.) plants of CuCu and cucu genotypes. In contrast to other plant parts, very young leaves and stems of CuCu plants displayed high phenylalanine ammonia-lyase activity. Initial leaf samples from CuCu plants were approximately 3 times as high in enzyme activity as leaves from cucu plants, but stems were only slightly higher in activity. Defoliation of the plants resulted in decreased enzyme activity, increased o-hydroxycinnamic acid content, and essentially no difference in enzyme activity between the genotypes. It appears that phenylalanine ammonia-lyase activity in leaves is not primarily controlled by the Cu/cu alleles and that the reaction catalyzed by this enzyme is not the limiting step in o-hydroxycinnamic acid synthesis.