ABSTRACT
This chapter deals with the specific changes to plant biochemistry that endow resistance to herbicides. Any biochemical change that allows a plant to survive herbicide application can be selected. Resistance can result from changes to the herbicide target site such that binding of the herbicide is reduced, or over-expression of the target site may occur. The chapter considers major mechanisms of resistance to herbicides in weed species where resistance has evolved in the field. Understanding the biochemistry and genetics of multiple-resistance is considerably more challenging as a result of having to separate the resistance mechanisms. The intensive use of herbicides to control weeds inevitably has resulted in the evolution of herbicide-resistant weed populations. On surveying the large body of work on resistance mechanisms, it is clear that the majority of studied examples relate to changes in the target enzyme.
