A Val-202-Phe α-tubulin mutation and enhanced metabolism confer dinitroaniline resistance in a single Lolium rigidum population.

BACKGROUND A Lolium rigidum population collected from Western Australia was previously reported as highly resistant to dinitroaniline herbicides mainly due to a Val-202-Phe substitution in the target site alpha-tubulin protein. To further determine the contribution of the 202 mutation to resistance, two sub-populations, respectively comprising the 202 mutant and wild-type (WT) individuals, were isolated from within the same resistant population and subject to dinitroaniline herbicide doses. A rice transgenic study was conducted to demonstrate whether the amino acid substitution at the 202 residue confers resistance. In addition, as indicated in the phenotyping and genotyping study, non-target enhanced trifluralin metabolism was further examined in the same population. RESULTS The 202 mutants were more resistant than the wild-type plants. Rice calli transformed with the L. rigidum mutant alpha-tubulin gene (Val-202-Phe) were more resistant to dinitroaniline herbicides relative to calli transformed with the wild-type gene. Also, enhanced trifluralin metabolism was detected in the 202 mutants in comparison to the susceptible seedlings. CONLCUSION Both target-site Val-202-Phe alpha-tubulin mutation and non-target-site enhanced trifluralin metabolism co-exist in this dinitroaniline-resistant L. rigidum population. (c) 2019 Society of Chemical Industry