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

Birdsfoot Trefoil (Lotus corniculatus L. cv. Leo), is a perennial forage legume that has difficulty in establishing stands due to slow seedling growth, weed competition and herbicide sensitivity. The development of herbicide resistant cultivars would be of economic importance. Resistant lines were isolated after sequential selection at the callus, shoot and whole plant levels to the sulfonylurea (SU) herbicides Harmony (DPX-M6316, code name for methyl 3- ( ( ((4-methoxy-6-methyl-1,3,5,triazine-2-yl)amino) carbonyl) amino) sulfonyl-2-thiophenecarboxylate), or Classic (DPX-F6025, code name for 2(( (4-chloro-6-methoxypyrimidine-yl)amino carbonyl) aminosulfonyl)benzoic acid ethyl ester. In field and growth chamber tests the Harmony regenerant lines displayed an increased tolerance as compared to control plants from tissue culture, and from seed. Results of the 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. It is concluded that herbicide resistant birdsfoot trefoil cultivars can be isolated using in vitro selection