The development of sulfonylurea herbicide-resistant birdsfoot trefoil (Lotus corniculatus) plants from in vitro selection.

Herbicide-resistant lines of birdsfoot trefoil (Lotus corniculatus L. cv ‘Leo’) were isolated after sequential selection at the callus, shoot, and whole plant levels to the sulfonylurea (SU) herbicide Harmony {DPX-M6316; 3-[[[(4-methoxy-6methyl-1,3,5, triazine-2-yl) amino] carbonyl] amino] sulfonyl-2-thiophenecarboxylate}. In field and growth chamber tests the Harmony regenerant lines displayed an increased tolerance as compared to control plants from tissue culture and controls grown from seed. Results of evaluation of callus cultures of regenerated mutant lines signify stability of the resistance. Outcrossed seeds collected from field trials, and tested in vitro for herbicide resistance, indicate that the trait is heritable and that resistance may be due to reduced sensitivity of acetolactate synthase to SU inhibition. Genetically stable herbicide-resistant lines of birdsfoot trefoil were successfully isolated using in vitro selection.