Abstract
Several cytochromes P450 (P450s) are involved in the biosynthesis of phtohormones in higher plants. Genome sequencing projects of Physcomitrella patents and Selaginella moellendorffii have revealed that some orthologous genes to phytohormone-related P450s from the flowering plants may be present in bryophyte and pteridophyte. We think that the comparative analysis of plant P450s conserved across the evolutionary stages can give us a clue to study the evolutionary aspects of phytohormone homeostasis. In this study, we performed functional analysis of putative brassinosteroid-biosynthetic P450s from P. patents and S. moellendorffii. We have found that CYP763A1 and CYP763B1/B2 from P. patents and CYP90E1/E2/E3 and CYP90F1 from S. moellendorffii may be the orthologs of brassinosteroid-biosynthetic P450s from the flowering plants. We have isolated the full-length cDNAs of the P450s except for CYP90F1 by RT-PCR. The recombinant P450 proteins were expressed in E. coli and with a baculovirusinsect cell system in order to analyze their catalytic activities in vitro. Now, we are looking for their proper substrates among the BR-biosynthesis intermediates and try to reveal the enzymatic reactions catalyzed by them.
