6533b871fe1ef96bd12d0b9f

RESEARCH PRODUCT

Genetic determinisms, evolution and detection of non-target-site based resistance to herbicides inhibiting acetolactate-synthase in rye-grass (Lolium sp.)

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The aim of this study is to unravel the genetic determinism of non-target-site resistance (NTSR) to herbicides inhibiting acetolactate-synthase (ALS) in the major weed rye-grass (Lolium sp.), and to estimate the feasibility of NTSR diagnosis based on genetic data. On the one hand, this work contributes to the understanding of the processes driving the evolution of NTSR to herbicides, and on the other hand it lays the foundations for the development of a diagnosis tool to identify NTSR to ALS inhibiting herbicides. - Using a quantitative transcriptome sequencing approach, we showed that NTSR evolve by recurrent selection of higher and higher constitutive expression levels of genes involved in pathways leading to the neutralization of herbicides or of their effects. Nineteen genes upregulated in plants with NTSR (marker genes) were identified. Gene amplification was observed for all marker genes and may be responsible for the up-regulation of some of them. - The selection of NTSR due to the deregulation of whole secondary metabolism pathways in rye-grass may be facilitated by “safeners” which are compounds applied in association with herbicides to ensure crop selectivity by enhancing NTSR-like metabolism pathways in crops. - The mechanisms at the root of NTSR seem to be conserved among rye-grass populations with different geographic origins in France (redundant evolution of the same mechanisms). - The NTSR marker genes identified in this work provided a proof of the feasibility of the diagnosis of NTSR to ALS inhibiting herbicides based on the study of the expression levels of a subset of the most informative marker genes (RNA quantification). NTSR detection based on the study of gene amplification of the most informative marker genes, or possibly on the identification of polymorphic variants frequently present in resistant plants, may also be possible. Both approaches remain to be validated on a broad and diverse set of rye-grass populations.