Formation of putrescine and cinnamoyl putrescines in tobacco cell cultures

A p-fluorophenylalanine- (PFP) resistant cell line of Nicotiana tabacum and wild type cells accumulating high and low levels of cinnamoyl putrescines, respectively, were used to study the formation of putrescine in the biosynthesis of cinnamoyl putrescines. Labelled arginine and ornithine were equally well incorporated into the main conjugates caffeoyl and feruloyl putrescine. Trapping experiments indicated that both amino acids were decarboxylated for putrescine biosynthesis. Nearly all alcohol-extractable radioactivity from the labelled amino acids was found as cinnamoyl putrescines in the PFP-resistant cell line, whereas wild type cells retained significant radioactivity in the amino acids. The enzyme activities of arginine and ornithine decarboxylases in the resistant cell line were increased 3- to 6-fold.