Uniconazole, a cytochrome P450 inhibitor, inhibits trans-zeatin biosynthesis in Arabidopsis

Cytokinin (CK) is a plant hormone that plays important regulatory roles in many aspects of plant growth and development. Although functions of CK and its biosynthesis pathway have been studied extensively, there is still no efficient biosynthesis inhibitor, which would be useful for studying CK from a chemical genetic approach. Here, CK biosynthesis inhibitor candidates were searched for using a systematic approach. In silico screening of candidates were carried out using genome-wide gene expression profiles and prediction of target sites using global CK accumulation profile analysis. As a result of these screenings, it was found that uniconazole, a well known inhibitor of Cytochrome P450 monooxygenase, prevents the biosynthesis of trans-zeatin, and that its target is CYP735As in Arabidopsis.