METHODS AND COMPOSITIONS FOR ISOLATING， IDENTIFYING AND CHARACTERIZING MONOCOT PLASTIDIC ACCASE HERBICIDE TOLERANT MUTATIONS USING A MODEL SYSTEM

The present invention relates to methods of producing， isolating， identifying and characterizing herbicide tolerant ACCase variants. In one embodiment， the invention encompasses a method of screening for an acetyle-CoA carboxylase (ACCase) enzyme which is tolerant to at least one herbicide， comprising: a) providing an ACCase-deficient yeast with a chimeric ACCase， said chimeric ACCase comprising: at least two regions that further comprise: i) an N-terminal region， said N-terminal region derived from yeast， fungi or monocot cytoplasmic ACCases， preferably a yeast ACCase; ii) a C-terminal region， said C-terminal region derived from monocot plastific ACCases and comprising an HSR; and iii) said N-terminal region comprises about 50% to about 60% of the chimeric ACCase; b) isolating herbicide tolerant yeast cells after culturing in the presence of at least one herbicide; and c) further comprising identifying the mutation(s) not present in chimeric ACCase prior to culturing， which confers tolerance to at least one herbicide.