Chapter Six - Function and Evolution of Plant Cytochrome P450

This chapter introduces P450 protein organization and catalytic mechanism, describes the P450 superfamily of genes, and summarizes the present view of the function and evolution of cytochrome P450 (CYP) genes in plants. An excellent overview of P450 mechanisms and genetics can be found in several recent reviews, some of which have addressed specifically different aspects of P450 in plants. The number of distinct P450s in plants is exceptionally large. In A. thaliana , the estimated number is 285–290. Some plants, with larger or amphiploid genomes, may have substantially more. In sharp contrast, Caenorhabditis elegans has 81 P450s. The estimated number in humans is 49 + 15 pseudogenes. Yeast has only three. The remarkable diversification of this gene superfamily in higher plants appears to be linked to the crucial roles of P450s at the interface between plants and their environment.