Content area
Abstract
The Dendrobium genus belongs to the Orchidaceae family and includes a broad range of terrestrial, epiphytic, and lithophytic plants. The genus includes many well-loved ornamental plants and valuable sources of traditional Chinese herbal medicines. Although popular and useful, their slow growth and vulnerability to environmental stress has strongly limited their more widespread adoption. The aim of our research is to expand the understanding of the regulation of Dendrobium growth and development. In this study, the gene encoding EREB5, a member of the APETALA2/ethylene-responsive element-binding protein (AP2/EREBP) family of transcription factors, was cloned from Dendrobium officinale. The full-length ORF of 558 bp, is predicted to code for a protein of 185 amino acids. The putative protein contains one copy of the well-conserved AP2 domain and a typical EAR motif, present in members of the ethylene response factor (ERF) subfamily. Arabidopsis thaliana plants ectopically expressing the DoEREB5 gene showed several phenotypic differences from wild-type plants, including altered leaf shape and petiole size. Expression of a DoEREB5 RNAi construct in Arabidopsis led to reduced levels of the putative Arabidopsis ortholog, AtERF9. Plants with reduced levels of AtERF9 showed an increase in chlorophyll content and photosynthetic rates compared to wild-type and heterologous ectopic DoEREB5 expression plants. Photosynthetic rates in the RNAi plants were higher than those in WT plants under both high and low light. Our results have provided clues as to the in vivo role of the Dendrobium gene, DoEREB5, suggesting that it is involved in the important processes of leaf development and function.