A Rapid Phenotyping Method for Imazamox Resistance in Wheat

Abstract

The availability of imidazolinone (IMI) resistant cultivars has provided an effective option for weed control in wheat production systems. IMI herbicides control several weeds, including Avena fatua and Lolium multiflorum, which are the most frequent grass weeds in wheat crops of the Argentine Pampas. The aim of this study was to develop a soil-less method that allows rapid phenotyping of IMI resistance in wheat. Nine wheat cultivars differing in IMI resistance were evaluated through a between-paper germination method. Herbicide concentrations required to reduce shoot and root length by 50% for resistant cultivars were > 75 fold that of the susceptible cultivars. The response of resistant and susceptible commercial cultivars was assessed in the between-paper and top-paper methods at 100 mM imazamox as discriminating dose. The Z’-factor was calculated for evaluation of the quality of the screening methods. Both germination methods showed Z’-factors > 0 indicating that the assays were appropriate but the between-paper method allowed to save space in the growth chamber. The germination methods were useful for distinguishing between susceptible and resistant plants carrying at least one resistance gene. The rapid, simple and cost-effective method described in the present study could be a potential tool when selecting for IMI resistance in wheat in breeding programs.

An integrated approach for the characterization of one‐ and two‐gene imazamox‐resistant wheat lines

“…The seedling response to imazamox was evaluated under controlled conditions using a top‐paper germination test (Breccia, Bisio, Picardi, & Nestares, 2018). Seeds were placed on germination paper moistened with different concentrations of commercial imazamox (0, 10, 100, and 316 μM) inside a polypropylene box.…”

Evaluation of bioassay methods to screen winter wheat for quizalofop herbicide tolerance

“…The differences in discriminatory doses between the Group 1 herbicides were due to the different mutations at the site of action and different patterns of resistances between Aryloxyphenoxy propionate (fop) and Cyclohexanedione (dim) herbicides (Beckie et al, 2000). Clearfield wheat, resistant to the ALS inhibitor Imidazolinone herbicide uses the SI bioassay method to differentiate between trait and nontrait seedlings, which is why it was hypothesized that CoAXium wheat could be tested using the SI method (Breccia et al, 2018).…”