Simultaneous reduction of the activity of two related enzymes, involved in early steps of the polyamine biosynthetic pathway, by a single antisense cDNA in transgenic rice.

Transgenic rice cell lines transformed with a heterologous cDNA derived from the arginine decarboxylase gene of oat, in an antisense orientation, exhibited significant (P < 0.05) down-regulation of the activity of the endogenous arginine and ornithine decarboxylases, compared to wild type and controls transformed only with the selectable marker (hpt). Changes in enzyme activity were reflected in a marked decrease in the level of putrescine (P < 0.