Differential expression of DAHP synthase and chorismate mutase in various organs of Brassica juncea and the effect of external factors on enzyme activity
R. Sharma et al., Differential expression of DAHP synthase and chorismate mutase in various organs of Brassica juncea and the effect of external factors on enzyme activity, PHYSL PLANT, 105(4), 1999, pp. 739-745
The multibranched shikimic acid pathway was discovered as the biosynthetic
route to the aromatic amino acids phenylalanine, tyrosine and tryptophan an
d a host of other secondary metabolites, An extensive body of work is avail
able on the characterization of various enzymes of this pathway in order to
understand the underlying mechanisms of aromatic amino acid biosynthesis a
nd secondary metabolism in higher plants. In the present investigation, sel
ective assays, based on feedback regulation patterns and divalent cation re
quirements, mere used to monitor the isozyme profiles of two of the key reg
ulatory enzymes of this pathway. 3-Deoxy-D-arabino heptulosonate-7-phosphat
e synthase (DAHP synthase/DS) (EC 4.1.2.15) and chorismate mutase (CM) (EC
5.4.99.4) have been characterized from different vegetative and reproductiv
e organs of Brassica juncea cv, Pusa Bold, An attempt has also been made to
investigate the effect of external factors, such as light and wounding on
the regulation of these enzymes. The results reveal differential expression
of DAHP synthase and CM in various organs of Brassica and an adaptability
of plants to various stresses by up or down regulation of these enzymes.