Plants as hosts for heterologous cytochrome P450 expression

Higher plant species, particularly tobacco, have been used as hosts for expression of both eucaryotic and procaryotic cytochromes P450. Strategies for subcellular localization and for providing access to a source of reducing equivalents have varied. While expression of the P450 gene can be confirmed by the appearance of mRNA or antigen, recovery of activity for in vitro studies is very difficult. Some plant-expressed heterologous cytochromes P450 dramatically alter the phenotype of the plant, so in vivo activity such as premature senescence or P450-specific alterations in herbicide sensitivity confirm that expression of a functional protein has occurred.