Effect of Glyphosate on Carrot and Tobacco Cells 1

• Published in: Plant physiology (Bethesda) 1977-07, Vol.60 (1), p.40-43
• Main Authors: Haderlie, Lloyd C., Widholm, Jack M., Slife, Fred W.
• Format: Article
• Language: English
• ISSN: 0032-0889; 1532-2548

The growth of suspension-cultured carrot ( Daucus carota L.) and tobacco ( Nicotiana tabacum L. cv. Xanthi) cells was inhibited by glyphosate (N-[phosphonomethyl]glycine). This inhibition was reversed by adding combinations of phenylalanine, tyrosine, and tryptophan or casein hydrolysate. Casein hydrolysate and phenylalanine + tyrosine + tryptophan were the most effective treatments. Reversal of glyphosate-induced inhibition occurred only if the aromatic amino acids were added during the first 8 days of glyphosate incubation. Glyphosate uptake was not reduced when the aromatic amino acids or casein hydrolysate were added. Even though phenylalanine biosynthesis is a suggested site for glyphosate action, inhibitory levels of glyphosate did not lower free phenylalanine concentrations in carrot cells within 10 days. 14 C-Phenylalanine studies indicated that the metabolic pool size was, likewise, not decreased. In carrot cells total free amino acids increased within 6 hours after glyphosate addition. Cell protein levels declined within 48 hours following glyphosate treatment. Studies on 14 C-thymidine and 14 C-uridine incorporation were complicated by rapid metabolism of these compounds to 14 CO 2 .