Expression of Arabidopsis thaliana cytochrome P450 monooxygenase, CYP71A12, in yeast catalyzes the metabolism of herbicide pyrazoxyfen

In higher plants, cytochrome P450 (P450, CYP) monooxygenases play important roles in the biosynthesis and metabolism of endogenous compounds and/or in the oxidative reactions of xenobiotics, such as herbicides, insecticides, and fungicides. In this study, the novel P450 cDNAs encoding CYP71A12 was isolated from wild-type Arabidopsis thaliana ecotype Ws using an RT-PCR strategy. Northern blot analysis revealed that cyp71A12 is expressed specifically in roots but not in flowers, leaves, or stems. To determine the function of CYP71A12, the coding sequences of the corresponding cDNAs were expressed in Saccharomyces cerevisiae AH22 cells. Microsomal fractions expressing CYP71A12 metabolized the herbicide pyrazoxyfen. Liquid chromatography mass spectrometry (LC/MS) analysis indicated that the metabolite of pyrazoxyfen might be N-demethylated at the pyrazole ring and 5-hydroxylated at the dichlorobenzene ring. This is the first report that a pyrazole herbicide is metabolized by a plant P450 species.