Development of a Non-GMO Herbicide Resistance System for Grass Control in Seashore Paspalum.

Herbicide resistance has been a sought-after trait to improve weed control options in turfgrasses; however attempts to commercialize genetically modified (GM) turfgrasses have been unsuccessful.  Sethoxydim is a grass-specific herbicide in the ACCase family.  Naturally occurring resistance to sethoxydim and other ACCase herbicides has been reported in several grass species as a result of single base-pair mutations.  Research was initiated to develop a novel source of resistance to sethoxydim in seashore paspalum (Paspalum vaginatum, Swartz).  In vitro selection and regeneration using tissue culture were used to select for naturally occurring mutations conferring herbicide resistance.  Callus was induced from immature inflorescences then plated on callus induction medium containing 10 µM sethoxydim for selection. Green plants were regenerated from resistant callus, the Ile to Leu mutation known to confer sethoxydim resistance was documented, and expression of herbicide resistance confirmed.  New sethoxydim resistant seashore paspalum experimental lines are now under field evaluation to determine their potential as a new tool to manage bermudagrass and other problematic grasses in seashore paspalum turf.