Distinct Detoxification Mechanisms Confer Resistance to Mesotrione and Atrazine in a Population of Waterhemp

  • Rong Ma
    Department of Crop Sciences, University of Illinois, Urbana, Illinois 61801 (R.M., P.J.T., C.W.R., D.L.M., A.G.H., D.E.R.); and
  • Shiv S. Kaundun
    Syngenta, Jealott’s Hill International Research Centre, Bracknell, Berkshire RG42 6EY, United Kingdom (S.S.K., T.H., E.M.)
  • Patrick J. Tranel
    Department of Crop Sciences, University of Illinois, Urbana, Illinois 61801 (R.M., P.J.T., C.W.R., D.L.M., A.G.H., D.E.R.); and
  • Chance W. Riggins
    Department of Crop Sciences, University of Illinois, Urbana, Illinois 61801 (R.M., P.J.T., C.W.R., D.L.M., A.G.H., D.E.R.); and
  • Daniel L. McGinness
    Department of Crop Sciences, University of Illinois, Urbana, Illinois 61801 (R.M., P.J.T., C.W.R., D.L.M., A.G.H., D.E.R.); and
  • Aaron G. Hager
    Department of Crop Sciences, University of Illinois, Urbana, Illinois 61801 (R.M., P.J.T., C.W.R., D.L.M., A.G.H., D.E.R.); and
  • Tim Hawkes
    Syngenta, Jealott’s Hill International Research Centre, Bracknell, Berkshire RG42 6EY, United Kingdom (S.S.K., T.H., E.M.)
  • Eddie McIndoe
    Syngenta, Jealott’s Hill International Research Centre, Bracknell, Berkshire RG42 6EY, United Kingdom (S.S.K., T.H., E.M.)
  • Dean E. Riechers
    Department of Crop Sciences, University of Illinois, Urbana, Illinois 61801 (R.M., P.J.T., C.W.R., D.L.M., A.G.H., D.E.R.); and

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<jats:title>Abstract</jats:title> <jats:p>Previous research reported the first case of resistance to mesotrione and other 4-hydroxyphenylpyruvate dioxygenase (HPPD) herbicides in a waterhemp (Amaranthus tuberculatus) population designated MCR (for McLean County mesotrione- and atrazine-resistant). Herein, experiments were conducted to determine if target site or nontarget site mechanisms confer mesotrione resistance in MCR. Additionally, the basis for atrazine resistance was investigated in MCR and an atrazine-resistant but mesotrione-sensitive population (ACR for Adams County mesotrione-sensitive but atrazine-resistant). A standard sensitive population (WCS for Wayne County herbicide-sensitive) was also used for comparison. Mesotrione resistance was not due to an alteration in HPPD sequence, HPPD expression, or reduced herbicide absorption. Metabolism studies using whole plants and excised leaves revealed that the time for 50% of absorbed mesotrione to degrade in MCR was significantly shorter than in ACR and WCS, which correlated with previous phenotypic responses to mesotrione and the quantity of the metabolite 4-hydroxy-mesotrione in excised leaves. The cytochrome P450 monooxygenase inhibitors malathion and tetcyclacis significantly reduced mesotrione metabolism in MCR and corn (Zea mays) excised leaves but not in ACR. Furthermore, malathion increased mesotrione activity in MCR seedlings in greenhouse studies. These results indicate that enhanced oxidative metabolism contributes significantly to mesotrione resistance in MCR. Sequence analysis of atrazine-resistant (MCR and ACR) and atrazine-sensitive (WCS) waterhemp populations detected no differences in the psbA gene. The times for 50% of absorbed atrazine to degrade in corn, MCR, and ACR leaves were shorter than in WCS, and a polar metabolite of atrazine was detected in corn, MCR, and ACR that cochromatographed with a synthetic atrazine-glutathione conjugate. Thus, elevated rates of metabolism via distinct detoxification mechanisms contribute to mesotrione and atrazine resistance within the MCR population.</jats:p>

収録刊行物

  • Plant Physiology

    Plant Physiology 163 (1), 363-377, 2013-07-19

    Oxford University Press (OUP)

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