Effects of alpha-aminooxy-beta-phenylpropionic acid on phenylalanine metabolism in p-fluorophenylalanine sensitive and resistant tobacco cells.

A p-fluorophenylalanine (PFP) resistant cell line with high phenylalanine ammonia lyase (PAL) activity and wild type cells with low PAL activity were compared in their responses to PAL inhibition by alpha-aminooxy-beta-phenylpropionic acid (AOP). Inhibition of PAL reduced the levels of the main phenolic compounds to 30% of the controls. Free phenylalanine pools increased 17 fold in the resistant line and 6 fold in the sensitive line, respectively. The accumulation of phenylalanine did not reduce the flow of labeled shikimic acid into the aromatic amino acids tyrosine and phenylalanine. The results are discussed with respect to the feedback inhibition of chorismate mutase activity by phenylalanine and tyrosine in both cell lines.