Resistance mechanisms to dinitroaniline herbicides in annual ryegrass (Lolium rigidum Gaudin)

Dinitroanilines (trifluralin, pendimethalin etc.) have been used as pre-emergence herbicides for ryegrass control for decades. With the dinitroaniline resistance evolution escalating, revealing dinitroaniline resistance mechanisms is of high importance. By investigating four trifluralin-resistant annual ryegrass populations, target-site a-tubulin mutations (including known Val-202-Phe, Thr-239-lle mutations and novel Arg-243-Lys/Met mutations), and non-target-site enhanced trifluralin metabolism were identified to confer dinitroaniline resistance. Additionally, the target-site resistance was mainly inherited as a nuclear-controlled recessive trait. And the Arg-243-Met mutation was found to incur profound changes in plant morphology. This knowledge is helpful for developing better weed management strategies to mitigate dinitroaniline resistance.