A high diversity of mechanisms endows ALS-inhibiting herbicide resistance in the invasive common ragweed (Ambrosia artemisiifolia L.)

Abstract

Ambrosia artemisiifolia L. (common ragweed) is a globally invasive, allergenic, troublesome arable weed. ALS-inhibiting herbicides are broadly used in Europe to control ragweed in agricultural fields. Recently, ineffective treatments were reported in France. Target site resistance (TSR), the only resistance mechanism described so far for ragweed, was sought using high-throughput genotyping-by-sequencing in 213 field populations randomly sampled based on ragweed presence. Additionally, non-target site resistance (NTSR) was sought and its prevalence compared with that of TSR in 43 additional field populations where ALS inhibitor failure was reported, using herbicide sensitivity bioassay coupled with ALS gene Sanger sequencing. Resistance was identified in 46 populations and multiple, independent resistance evolution demonstrated across France. We revealed an unsuspected diversity of ALS alleles underlying resistance (9 amino-acid substitutions involved in TSR detected across 24 populations). Remarkably, NTSR was ragweed major type of resistance to ALS inhibitors. NTSR was present in 70.5% of the resistant plants and 74.1% of the fields harbouring resistance. A variety of NTSR mechanisms endowing different resistance patterns evolved across populations. Our study provides novel data on ragweed resistance to herbicides, and emphasises that local resistance management is as important as mitigating gene flow from populations where resistance has arisen.

Diversity and Spread of Acetolactate Synthase Allelic Variants at Position 574 Endowing Resistance in Amaranthus hybridus in Italy

“…Previous regional-scale studies in Europe focused on ALS-resistant barnyard grass ( Echinochloa spp.) [ 17 , 18 ], ALS-resistant common ragweed ( Ambrosia artemisiifolia L.) [ 19 ] and ALS or ACCase-resistant blackgrass ( Alopecurus myosuroides Huds.) [ 20 , 21 ].…”

Diversity of Herbicide-Resistance Mechanisms of Avena fatua L. to Acetyl-CoA Carboxylase-Inhibiting Herbicides in the Bajio, Mexico

“…This random distribution of biotypes and the lack of genetic structure in the populations are frequent in other agricultural regions [22]; the dispersion increases the complexity of the problem. For this reason, the distribution of herbicide-resistant populations is considered similar to epidemiological cases [23]. However, the most common situation in epidemiology is a unique origin and posterior dispersion.…”

Impact of new management practices on arable and field margin plant communities in sunflower, with an emphasis on the abundance of Ambrosia artemisiifolia (Asteraceae)

“…The use of compounds from the HRAC 2 group also poses the important risk of selecting for resistant species, which is already the case for A . artemisiifolia in France (Loubet et al, 2021). Several resistance situations have been detected to date, although still involving low proportions of resistant plants.…”

“…Some unintended effects that have not yet been detected may occur in the future, especially because, in some of the surveyed fields, farmers had only recently adopted this new practice. The use of compounds from the HRAC 2 group also poses the important risk of selecting for resistant species, which is already the case for A. artemisiifolia in France(Loubet et al, 2021). Several resistance situations have been detected to date, although still involving low proportions of resistant plants.…”