Para-Fluorophenylalanine Resistant Cell Lines of Tobacco

Abstract

Thirty-one p-fluorophenylalanine (PFP)-resistant cell lines of tobacco cell cultures ( Nicotiana tabacum L. cv. Xanthi, Nicotiana tabacum L. cv. Maryland Mammoth and Nicotiana glauca ) were selected in liquid media and on agar plates. Three of these cell lines were also resistant to 5-methyltryptophan (5-MT) indicating a resistance due to decreased uptake of amino acids and their analogs. Three lines of Nicotiana tabacum L. cv. Maryland Mammoth and three of Nicotiana glauca accumulated higher levels of phenylalanine and tyrosine and became likely resistant to PFP due to the overproduction of the corresponding natural amino acids. All five lines of Nicotiana tabacum L. cv. Xanthi, one of Nicotiana tabacum L. cv. Maryland Mammoth and five of Nicotiana glauca accumulated higher levels of phenolics. Decreased uptake of an analog or dilution of the toxic antimetabolite by enlargement of the pool size of the corresponding natural amino acid are reasonable explanations for acquired resistance. The often observed concomitant occurrence of PFP-resistance with increased levels of phenolics is discussed.