ABC transporters linked to multiple herbicide resistance in blackgrass (Alopecurus myosuroides)

Abstract

Enhanced detoxification is a prominent mechanism protecting plants from toxic xenobiotics and endows resistance to diverse herbicide chemistries in grass weeds such as blackgrass (Alopecurus myosuroides). The roles of enzyme families which impart enhanced metabolic resistance (EMR) to herbicides through hydroxylation (phase 1 metabolism) and/or conjugation with glutathione or sugars (phase 2) have been well established. However, the functional importance of herbicide metabolite compartmentalisation into the vacuole as promoted by active transport (phase 3), has received little attention as an EMR mechanism. ATP-binding cassette (ABC) transporters are known to be important in drug detoxification in fungi and mammals. In this study, we identified three distinct C-class ABCCs transporters namely AmABCC1, AmABCC2 and AmABCC3 in populations of blackgrass exhibiting EMR and resistance to multiple herbicides. Uptake studies with monochlorobimane in root cells, showed that the EMR blackgrass had an enhanced capacity to compartmentalize fluorescent glutathione-bimane conjugated metabolites in an energy-dependent manner. Subcellular localisation analysis using transient expression of GFP-tagged AmABCC2 assays in Nicotiana demonstrated that the transporter was a membrane bound protein associated with the tonoplast. At the transcript level, as compared with herbicide sensitive plants, AmABCC1 and AmABCC2 were positively correlated with EMR in herbicide resistant blackgrass being co-expressed with AmGSTU2a, a glutathione transferase (GST) involved in herbicide detoxification linked to resistance. As the glutathione conjugates generated by GSTs are classic ligands for ABC proteins, this co-expression suggested AmGSTU2a and the two ABCC transporters delivered the coupled rapid phase 2/3 detoxification observed in EMR. A role for the transporters in resistance was further confirmed in transgenic yeast by demonstrating that the expression of either AmABCC1 or AmABCC2, promoted enhanced tolerance to the sulfonylurea herbicide, mesosulfuron-methyl. Our results link the expression of ABCC transporters to enhanced metabolic resistance in blackgrass through their ability to transport herbicides, and their metabolites, into the vacuole.

Mechanistic understanding and sustainable management of non-target site herbicide resistance in modern day agriculture

“…According to recent study, ABC transporters played an important role in translocating metabolites across membranes through ATP hydrolysis and were additionally involved in the compartmentation and detoxification of herbicides in Alopecurus myosuroides Huds. as confirmed by transcriptomic analysis (Goldberg-Cavalleri et al, 2023).…”

“…Rather, efforts were made to summarize the wide array of resistance mechanisms. Most of the NTSR mechanisms are not fully understood (Baucom, 2019, Goldberg-Cavalleri et al, 2023, however, this review will provide an account of what is known about these mechanisms. The review further discusses how various herbicide resistance management strategies delay resistance evolution, with emphasis on NTSR.…”

Selective herbicide safening in dicot plants: a case study in Arabidopsis

“…These GSTs from monocot species were selected based on their activity toward herbicides. Sequences were aligned and trimmed as described previously ( Goldberg-Cavalleri et al., 2023 ). Automatic model selection mode was employed (Bayesian information Criterion selecting the model LG+G4+I+F), with branch support values calculated by Ultrafast bootstrap approximation.…”

Comprehensive insights into herbicide resistance mechanisms in weeds: a synergistic integration of transcriptomic and metabolomic analyses

“…Herbicides have been used to control weeds and increase the quality and quantity of major crops since their discovery. However, repeated use of similar herbicidal modes of action (MOAs) and the associated selection pressure have led to the evolution of herbicide resistance in varieties of economically important weedy species such as Alopecurus myosuroides ( Lan et al., 2022 ; Goldberg-Cavalleri et al., 2023 ), Amaranthus palmeri ( Manicardi et al., 2023 ), Apera spica venti ( Košnarová et al., 2021 ; Papapanagiotou et al., 2022 ), Bromus sterilis ( Sen et al., 2021 ), Lolium spp ( Tehranchian et al., 2019 ; Ma et al., 2020 ; Zhu et al., 2023 ). Recent studies showed that the majority of these weeds were also developing multiple resistances against herbicides with more than one mode of action ( Tehranchian et al., 2019 ; Ma et al., 2020 ; Košnarová et al., 2021 ; Lan et al., 2022 ; Papapanagiotou et al., 2022 ; Zhu et al., 2023 ).…”