Evolution of herbicide resistance mechanisms in grass weeds

• Published in: Plant science (Limerick) 2014-12, Vol.229, p.43-52
• Main Authors: Matzrafi, Maor, Gadri, Yaron, Frenkel, Eyal, Rubin, Baruch, Peleg, Zvi
• Format: Article
• Language: English
• Subjects: ACCase inhibitors; Acetyl-CoA Carboxylase - antagonists & inhibitors; Acetyl-CoA Carboxylase - metabolism; ALS/AHAS inhibitors; Amino Acid Sequence; Arabidopsis - metabolism; Brachypodium; Brachypodium - drug effects; Brachypodium - genetics; Ecosystem; EPSPS inhibitor; Evolution, Molecular; Halogenated Diphenyl Ethers - toxicity; Herbicide detoxification; Herbicide Resistance - genetics; Heterocyclic Compounds, 2-Ring - toxicity; Israel; Molecular Sequence Data; Photosystem II Protein Complex - metabolism; Plant Proteins - chemistry; Plant Weeds - drug effects; Plant Weeds - genetics; PSII inhibitors
• ISSN: 0168-9452; 1873-2259
• DOI: 10.1016/j.plantsci.2014.08.013

•TS resistance to PSII inhibitors was associated with significant fitness cost.•NTS resistance was found regardless of herbicide application history.•CYT-P450-based detoxification conferred ACCase resistance in Brachipodium.•BrIFAR offers a new and improved weed management for agricultural practice. Herbicide resistant weeds are becoming increasingly common, threatening global food security. Here, we present BrIFAR: a new model system for the functional study of mechanisms of herbicide resistance in grass weeds. We have developed a large collection of Brachypodium accessions, the BrI collection, representing a wide range of habitats. Wide screening of the responses of the accessions to four major herbicide groups (PSII, ACCase, ALS/AHAS and EPSPS inhibitors) identified 28 herbicide-resistance candidate accessions. Target-site resistance to PSII inhibitors was found in accessions collected from habitats with a known history of herbicide applications. An amino acid substitution in the psbA gene (serine264 to glycine) conferred resistance and also significantly affected the flowering and shoot dry weight of the resistant accession, as compared to the sensitive accession. Non-target site resistance to ACCase inhibitors was found in accessions collected from habitats with a history of herbicide application and from a nature reserve. In-vitro enzyme activity tests and responses following pre-treatment with malathion (a cytochrome-P450 inhibitor) indicated sensitivity at the enzyme level, and give strong support to diclofop-methyl and pinoxaden enhanced detoxification as NTS resistance mechanism. BrIFAR can promote better understanding of the evolution of mechanisms of herbicide resistance and aid the implementation of integrative management approaches for sustainable agriculture.