A Novel AHAS-Inhibiting Herbicide Candidate for Controlling Leptochloa chinensis : A Devastating Weedy Grass in Rice Fields.

Given the prevalence of the malignant weed Chinese Sprangletop ( Leptochloa chinensis (L.) Nees) in rice fields, the development of novel herbicides against this weed has aroused wide interest. Here, we report a novel diphenyl ether-pyrimidine hybrid, DEP- 5 , serving as a systematic pre/postemergence herbicide candidate for broad-spectrum weed control in rice fields, specifically for L. chinensis . Notably, DEP- 5 exhibits over 80% herbicidal activity against the resistant biotypes even at 37.5 g a.i./ha under greenhouse conditions and has complete control of L. chinensis at 150 g a.i./ha in the rice fields. We uncover that DEP- 5 acts as a noncompetitive inhibitor of acetohydroxyacid synthase (AHAS) with an inhibition constant ( K i ) of 39.4 μM. We propose that DEP- 5 binds to AHAS in two hydrophobic-driven binding modes that differ from commercial AHAS inhibitors. Overall, these findings demonstrate that DEP- 5 has great potential to be developed into a herbicide for L. chinensis control and inspire fresh concepts for novel AHAS-inhibiting herbicide design.