Simultaneous suppression of three genes related to brassinosteroid (BR) biosynthesis altered campesterol and BR contents, and led to a dwarf phenotype in Arabidopsis thaliana.

We generated transgenic lines of Arabidopsis thaliana with an RNA interference construct that expressed hairpin double-stranded RNA for DET2:DWF4:SMT2 to induce sequence-specific RNA silencing. In transgenic plants, expressions of DET2, DWF4, and SMT2 were simultaneously reduced, and the campesterol content was increased by up to 420% compared to the level in the wild-type plant. Triple knock-down of the DET2, DWF4, and SMT2 enzymes also resulted in reduction of brassinosteroid (BR)-specific biosynthesis intermediates. Transgenic plants harboring the RNA interference construct displayed a semi-dwarf phenotype due to altered development. Our findings indicate that redesigning of plant architecture is possible through simultaneous suppression of multiple genes involved in BR biosynthesis.