Selection and characterization of a carrot cell line tolerant to glyphosate

Emerson D. Nafziger, Jack M. Widholm, Hans C. Steinrücken, John L. Killmer

Research output: Contribution to journalArticlepeer-review


Cultured carrot (Daucs carota L.) cells were adapted to growing in 25 millimolar glyphosate by transfer into progressively higher concentrations ofthe herbicide. Tolerance was increased 52-fold, and the adaptation was stable in the absence of glyphosate. The uptake of glyphosate was similar for adapted and nonadapted cells. Activity of the enzyme 5- enolpyruvylshikimic acid-3-phosphate synthase was 12-fold higher in the adapted line compared to nonadapted cells, while activities of shikimate dehydrogenase and anthranilate synthase were similr in the two cell types. The adapted cells had higher levels of free amino acids-especially threonine, methionine, tyrosine, phenylalanine, tryptophan, histidine, and arginine than did nonadapted cells. Glyphosate treatment caused decreases of 50 to 65% in the levels of serine, glycine, methionine, tyrosine, phenybaanine, and tryptophan in nonadapted cells, but caused little change in free amino acid levels in adapted cells. The adaptation reported here supports the growing body of evidence linking tolerance to glyphosate with increased levels of the enzyme 5- enolpyruvylshikimic acid-3-phosphate synthase. The elevated levels of aromatic amino acids, which may confer resistance in adapted cells, suggest that control of the shikimate pathway may be altered in these cells.

Original languageEnglish (US)
Pages (from-to)571-574
Number of pages4
JournalPlant physiology
Issue number3
StatePublished - 1984

ASJC Scopus subject areas

  • Physiology
  • Genetics
  • Plant Science


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