Metabolism of phenylalanine and tyrosine in tobacco cell lines resistant and sensitive to p-fluorophenylalanine

Chromatography of soluble polyphenols of p-fluorophenylalanine-sensitive and -resistant tobacco cells revealed that the 10-fold increased level found in the resistant line was largely due to the accumulation of two unidentified polyphenols. The uptake of Phe-U-¹⁴C] and Tyr-U-¹⁴C] by the resistant line was ca 10 % that by the sensitive line. About 90 % of the phenylalanine-¹⁴C] which was taken up by both cell lines could be accounted for as free phenylalanine in protein, soluble polyphenols or CO₂. The fate of Tyr-¹⁴C] was similar to that of phenylalanine except that the incorporation was into insoluble polymeric forms of polyphenols rather than into soluble polyphenols. The resistant line incorporated 9-times more phenylalanine-¹⁴C] into soluble polyphenols than did the sensitive line. The different ¹⁴C-aromatic amino acid accumulation and incorporation patterns noted with the two cell lines indicates that there are different active pools. Differential uptake rates by the two cell lines might affect the distribution of the absorbed amino acid among the different pools.