Résumé
Non-target-site-resistance (NTSR) to herbicides is a major cause for failure in the chemical control of a number of weeds, and is especially widespread and important in grass weeds. Although several gene families have been shown to be involved in NTSR (cytochromes p450, glutathione-S-transferases, glycosyl-transferases, ABC transporters, esterases…), the genetic determinants of NTSR are still poorly known to date. NTSR is part of the response of weeds to herbicides. To unravel NTSR, it is thus of interest to firstly characterise the processes involved in herbicide stress response in grasses. For this purpose, we implemented a comparative whole-transcriptome sequencing (RNA-seq) of resistant and sensitive plants of Lolium sp. before and after the application of an herbicide inhibiting ALS. The expression of transcripts encoding a total of 81,663 potential peptides was monitored over a time-course experiment ranging from before herbicide application to 48 hours after herbicide application. Comparison among experimental modalities allowed to identify Gene Ontology biological processes and molecular functions with a potential role in herbicide response and in NTSR. The role of the main gene families known to be involved in herbicide detoxification was confirmed in this study. We identified additional processes regulated by the herbicide application (e.g., transcripts involved in plant defence, in drug response, in the regulation of gene expression, in the branched amino-acid biosynthesis pathway, in photosynthesis or in excretion transport). Several transcripts with an expression pattern differentiating herbicide-resistant and herbicide-sensitive plants were also identified that are candidates of interest for NTSR diagnosis purposes.