Obtaining Sethoxydim Resistance in Seashore Paspalum.

Herbicide resistance has been a sought-after trait for turfgrasses, however attempts to commercialize GM turfgrasses have thus far been unsuccessful. Sethoxydim is a grass-specific herbicide, and resistance results from one of several single base-pair mutations. The most common mutation is an ILE to LEU substitution caused by an A to T mutation at position 1781 of ACCase. Research was initiated to develop a novel source of resistance to sethoxydim in seashore paspalum (Paspalum vaginatum Swartz). Our objectives were to develop in vitro selection and regeneration protocols necessary to select for naturally occurring mutations conferring herbicide resistance. A dose response experiment was performed to determine the optimum sethoxydim concentration for selection. Callus was induced from immature inflorescences then plated on callus induction medium containing sethoxydim for selection. Green plants were regenerated from resistant callus, the ILE to LEU mutation documented, and expression of herbicide resistance at the whole-plant level confirmed.