Pesticide metabolism in plants and microorganisms

Abstract

Understanding pesticide metabolism in plants and microorganisms is necessary for pesticide development, for safe and efficient use, as well as for developing pesticide bioremediation strategies for contaminated soil and water. Pesticide biotransformation may occur via multistep processes known as metabolism or cometabolism. Cometabolism is the biotransformation of an organic compound that is not used as an energy source or as a constitutive element of the organism. Individual reactions of degradation–detoxification pathways include oxidation, reduction, hydrolysis, and conjugation. Metabolic pathway diversity depends on the chemical structure of the xenobiotic compound, the organism, environmental conditions, metabolic factors, and the regulating expression of these biochemical pathways. Knowledge of these enzymatic processes, especially concepts related to pesticide mechanism of action, resistance, selectivity, tolerance, and environmental fate, has advanced our understanding of pesticide science, and of plant and microbial biochemistry and physiology. There are some fundamental similarities and differences between plant and microbial pesticide metabolism. In this review, directed to researchers in weed science, we present concepts that were discussed at a symposium of the American Chemical Society (ACS) in 1999 and in the subsequent book Pesticide Biotransformation in Plants and Microorganism: Similarities and Divergences, edited by J. C. Hall, R. E. Hoagland, and R. M. Zablotowicz, and published by Oxford University Press, 2001.

Safeners recruit multiple signalling pathways for the orchestrated induction of the cellular xenobiotic detoxification machinery in Arabidopsis

“…The selective action of safeners may rather be determined by the specificity of the detoxifying enzymes, resulting in a higher herbicide metabolizing activity in grass crops as compared with dicots. Indeed, variation in substrate specificity of GSTs and P450s in different plant species can result in herbicide selectivity (Barrett et al 1997;Van Eerd et al 2003;Yuan et al 2007;Zhang et al 2007a). Furthermore, GSTs with herbicidedetoxifying activity were shown to result in herbicide tolerance in dicots when overexpressed in appropriate tissues (Jepson et al 1997;Skipsey et al 2005;Benekos et al 2010), and the development of herbicide resistance in weeds is often because of increased activities of specific P450s (Siminszky 2006).…”

“…Likewise, species-specific differences in herbicide tolerance can also be explained by differences in GST activity and the capacity for herbicide detoxification by glutathionylation (Van Eerd et al 2003;Yuan, Tranel & Stewart 2007).…”

In vitro biotransformation of PBDEs by root crude enzyme extracts: Potential role of nitrate reductase (NaR) and glutathione S-transferase (GST) in their debromination

“…Metabolites of lower debrominated PBDEs and OH-PBDEs were also detected in plant tissues (Wang et al, 2011b), which demonstrates that plants are able to transform PBDEs from higherto lower-brominated congeners as well as to OH-PBDE congeners. Enzymatic transformation, mainly as the result of biotic processes mediated by plants, is by far recognized as the major route of organic degradation (Van Eerd et al, 2003). However, it still remains unclear how plant enzymes response to the exposure of PBDEs and what particular plant enzymes are responsible for PBDE biodegradation.…”

Influencia de las coberturas en cultivos de cítricos sobre los hongos formadores de micorrizas arbusculares en Oxisoles del piedemonte llanero colombiano

“…Este resultado es similar al observado por Wang et al (1993), quienes encontraron que la aplicación de herbicidas puede tener una influencia negativa sobre la esporulación y la colonización de los HFMA, pues afecta el establecimiento de la simbiosis entre los organismos. Al aplicar al suelo glifosato, herbicida fosforado, puede ser utilizado como fuente de carbono, nitrógeno y fósforo por algunas bacterias Gram (+) y Gram (-) (Van Eerd et al, 2003). La disminución de las esporas de micorrizas parece estar asociada a la menor cantidad de materia seca producida por el tratamiento y, por tanto, al desarrollo El uso indiscriminado de agroquímicos puede generar diferentes niveles de toxicidad que pueden inducir cambios en los procesos de colonización, formación y desarrollo de clamidiosporas, estructuras directamente relacionadas con la asociación de los HFMA y las raíces de especies vegetales (Cano y Lynch, 1990).…”