In Vitro Selection of Sethoxydim‐Resistant Creeping Bentgrass

Abstract

Creeping bentgrass (Agrostis stolonifera L.) is a fine‐textured, cold‐hardy turfgrass used by the golf industry in the transition zone and farther north. Grassy weeds are a recurrent problem for seed producers and golf course managers. Herbicide‐resistant creeping bentgrass would provide the seed producer and golf course manager with an additional tool to control grassy weeds. In the present study, in vitro selection was used to obtain mutants of creeping bentgrass via somaclonal variation that were resistant to the acetyl coenzyme A carboxylase (ACCase) inhibitor, sethoxydim {2‐[1‐(ethoxyimino] butyl)‐5‐[2‐(ethylthio)propyl]‐3‐hydroxy‐2‐cyclohexen‐1‐one}. Selection was imposed on creeping bentgrass calli (total of 13,725) by growing them on induction medium containing 10 µM sethoxydim. Four independent sethoxydim‐resistant calli were identified and subsequently sequenced to confirm the presence of an A to C mutation in the first position of the 1781 amino acid codon causing an isoleucine to leucine substitution. Whole plant dose response experiments showed the sethoxydim‐resistant event, SR1, was resistant to sethoxydim at rates of >3200 g a.i. ha–1. SR1 also showed cross resistance to the ACCase‐inhibitor herbicide, fenoxaprop at rates of > 800 g a.i. ha–1.