Discovery of Novel Aminopyridine Ethers as Promising Auxin Herbicides

Auxin herbicides are vital for agricultural weed management. To develop novel and efficient auxin herbicides, a series of aminopyridine ether compounds were designed and synthesized via fragment splicing. Postemergence herbicidal activity assays showed that compounds C6, C7, and C8 achieved 100% control against Echinochloa crusgalli (E.c.), Eleusine indica (E.i.), Setaria faberi (S.f.), Amaranthus retroflexus (A.r.), Abutilon juncea (A.j.), and Portulaca oleracea (P.o.) at 37.5 g a.i./ha. Especially, C8 provided over 70% control of all six weeds at 9.375 g a.i./ha. At 75 g a.i./ha, compounds C7 and C8 caused less damage to gramineous crops than fluchloraminopyr-tefuryl. Transcriptomic and metabolomic analyses demonstrated that C8 alters the expression of genes associated with plant growth, development and stress responses, and disrupts plant growth by interfering with auxin signal transduction and reducing the content of the key metabolite indole-3-acetic acid. The present work indicates that C8 possesses great potential as an auxin-type herbicide for weed control.