Cost effective Integrated Weed Management (IWM) involves combinations of non-chemical and chemical technologies adapted to the crops, the weed diversity, and environmental factors. When low diversity is present in the cropping system, including herbicide use, weed-herbicide-resistance can evolve with the results of poor weed control and significant crop losses. Herbicide-resistance has spread worldwide and concern a high number of weed species. It is of particular concern in certain locations in cereal, soybean, maize, cotton, and rice cropping systems. Among several resistance mechanisms, herbicide detoxification (EMR, enhanced metabolic resistance) can confer resistance to a broad spectrum of chemical classes representing one or several modes of action. Molecular elements involved in herbicide detoxification are still poorly characterized and understood. Recent data using RNA-Seq transcriptome analyses to identify genes conferring EMR resistant populations in rye-grass and Amaranthus populations resistant to different herbicides will be summarized and compared. Among genes overexpressed in the herbicide-resistant plants compared to the sensitive plants, several, including CytP450s, GSTs, and GTs, were validated by genetics (co-segregation with the resistant phenotype), and functionally, by biochemical activity on the herbicide compounds. For some of the characterized genes, structure activity was performed on a range of herbicides representing several chemical classes. In addition data on protein modelling and herbicide docking in the active site of detoxification enzymes will be presented. Not all overexpressed genes co-segregating with the resistance phenotype were found to be able to detoxify the herbicide(s) showing poor activity on a given resistant population. Possible resistance evolution mechanisms will be discussed in comparison to resistance evolution in other organisms, in particular in insects resistant to insecticides.

Genomics to characterize Cyt P450 function in herbicide metabolic resistance:  A review of recent works

256th National Meeting (2018)

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