Metabolism of Herbicides or Xenobiotics in Plants

Tracy M. Sterling
Department of Entomology, Plant Pathology and Weed Science at New Mexico State University, USA
Deana M. Namuth
Department of Agronomy and Horticulture at University of Nebraska-Lincoln, USA
Scott J. Nissen
Department of Bioagricultural Sciences and Pest Management at Colorado State University, USA


 

Overview

Herbicide detoxication via metabolism is the primary mechanism of selectivity for most herbicides. Selective weed control using herbicides often relies on the ability of tolerant crop plants to detoxify the herbicide more rapidly than weeds. The same processes used by plants to detoxify herbicides are used for other xenobiotics (foreign chemicals); therefore, these terms will be used interchangeably. In this lesson, we will explore in detail three major phases of herbicide metabolism in plants, the enzymes involved in those processes and the final fate of herbicide metabolites. In addition, how crop injury or weed sensitivity might be altered by synergists, antagonists or other factors that affect metabolism will be described. Involvement of herbicide metabolism in resistance will also be discussed.

Objectives:

At the completion of this lesson, learners will be able to:

1. Understand the importance of herbicide metabolism for crop tolerance (selectivity).
    
2. Identify the three major phases of xenobiotic metabolism in plants.
    
3. Explain the major enzyme systems involved during metabolism of xenobiotics in plants.
    
4. Provide examples of each major phase and understand how metabolism may also lead to herbicide bio-activation.