Developing a Dwarf Echinacea purpurea Line by Suppressing DWF3 Expression via RNA Interference

DWARF3 (DWF3) is a brassinosteroid (BR) biosynthesis-related enzyme that catalyzes the C-3 oxidation of early BR intermediates. For the first time, we isolated the EpDWF3 gene from Echinacea purpurea. EpDWF3 shares high homology with AtCYP90A1 and ZeCPD1, a steroid 23-alpha-hydroxylase involved in the BR-biosynthetic pathway. We generated transgenic Echinacea plants via transformation with an RNA interference (RNAi) construct that expresses hairpin double-stranded RNA for EpDWF3 to induce sequence-specific RNA silencing. The transgenic plants displayed dwarf phenotypes, including reduced plant height and small flower diameter. We confirmed the presence of the RNAi construct in the transgenic plants by genomic DNA PCR. The transcript level of EpDWF3 decreased by 48% in the transgenic plants compared to wild type. Our results indicate that the knock-down of BR biosynthesis-related genes by RNAi enables the production of valuable dwarf plants for commercial horticultural or agricultural applications.