LAUSR

Orchid plants develop protocorms upon germination and produce protocorm-like structures called protocorm-like bodies (PLBs) from protocorms and somatic cells via tissue culture. PLBs have broad technical application potentials in orchid industry and their regeneration is a distinct developmental process in the plant kingdom. However, little is known about this unparalleled developmental program. In this study, we identified a PLB-abundant gene, ethylene response factor (ERF), a transcription factor named DoERF5, and determined its important roles in PLB regeneration in Dendrobium orchid. Overexpression of DoERF5 in Dendrobium greatly enhanced the PLB regeneration from PLB and stem explants, and up-regulated the expression of WOUND INDUCED DEDIFFERENTIATION (DoWIND) homologs and SHOOT MERISTEMLESS (DoSTM), as well as the genes involved in cytokinin biosynthesis (DoIPT) and cytokinin response (DoARRs). However, silencing DoERF5 reduced the regeneration rate of PLBs, and down-regulated the expression of DoWIND homologs, DoSTM and DoARRs. We demonstrated that DoERF5 directly bound to the promoter of DoSTM and regulated its expression. In addition, overexpression of DoSTM in Dendrobium orchid resulted in favorable regeneration of PLBs. Our results clarify that DoERF5 regulates the regeneration of PLB by enhancing DoSTM expression. Our findings provide new insights into how the DoERF5 mediates PLB regeneration and offer technical potentials in improving clonal propagation, preservation and bioengineering of orchids. This article is protected by copyright. All rights reserved.