ABSTRACT
Aryloxyphenoxypropionate and cyclohexanedione herbicides comprise two families of herbicides with several derivatives of chemistry that all act through inhibition of acetyl-coenzyme A carboxylase (ACCase) in susceptible species. This chapter reviews the present status of selection and development of crop plants resistant to ACCase-inhibiting herbicides. Herbicide inhibition of ACCase inhibits incorporation of acetate into free fatty acids in isolated maize chloroplasts, in root tips, and in cell cultures. Resistance to ACCase inhibiting herbicides may be conferred by at least three different documented mechanisms: altered target site enzyme, metabolism, and an undetermined mechanism associated with altered membrane electrochemical properties. Plant cell and tissue culture technologies involve reduction of plant growth to the cell level, thereby maximizing the number of selectable units that can be screened for tolerance to biochemical inhibitors such as herbicides. Plant tissue cultures are usually grown in defined media under controlled environmental conditions, enabling optimization of selection conditions for recovery of the desired variant.
