Selective disruption of wheat secondary metabolism by herbicide safeners.
In wheat (Triticum aestivum L.), treatment with herbicide safeners enhances the expression of enzymes involved in pesticide detoxification and reduces crop sensitivity to herbicides. Since these same enzymes are involved in plant secondary metabolism, it was of interest to determine whether or not the safener cloquintocet mexyl perturbed phenolic metabolism in wheat seedlings. LC/ESI/MS analysis identified 14 phenolic substrates in the shoots of young wheat plants. Fragmentation imposed by collision induced dissociation identified specific C-glycosidic conjugates of 4',5,7-trihydroxflavone (apigenin), 3',4',5,7-tetrahydroxyflavone (luteolin) and 3'-O-methylluteolin. Treatment of 7-day-old wheat shoots with cloquintocet mexyl resulted in an accelerated depletion of the conjugates of all three flavones, most notably with the glycosides of luteolin. In contrast, safener treatment caused the selective accumulation of 4',5,7-trihydroxy-3',5'-dimethoxyflavone (tricin) and the phenylpropanoid ferulic acid. Changes in phenolic content were associated with an increase in O-methyltransferase and C-glucosyltransferase activity toward flavonoid substrates as well as the classic enhancement of detoxifying glutathione transferases. Our results suggest that in addition to altering the capacity of wheat to metabolise herbicides and other xenobiotics, safeners can also cause a selective shift in the metabolism of endogenous phenolics.
Centre for Bioactive Chemistry, Department of Biological Sciences, School of Biological and Biomedical Sciences, Durham University, South Road, Durham DH1 3LE, UK.
Ian
I
Cummins
Melissa
M
Brazier-Hicks
Maciej
M
Stobiecki
Rafa
R
Franski
Robert
R
Edwards
D002853:Chromatography, Liquid; D006540:Herbicides / Q000494:pharmacology*; D013058:Mass Spectrometry; D010636:Phenols / Q000378:metabolism; D014908:Triticum / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism
D006540:Herbicides; D010636:Phenols