DOAP1 Promotes Flowering in the Orchid Dendrobium Chao Praya Smile.

Nunchanoke Sawettalake,Lisha Shen,Yanwen Wang,Sumontip Bunnag,Hao Yu

doi:10.3389/fpls.2017.00400

Abstract

APETALA1 (AP1) encodes a key MADS-box transcription factor that specifies the floral meristem identity on the flank of the inflorescence meristem, and determines the identity of perianth floral organs in the model plant Arabidopsis thaliana. Orchids are members of the Orchidaceae, one of the largest families of angiosperms. Although the expression patterns of a few AP1-like genes in orchids have been reported, their actual functions in orchid reproductive development are so far largely unknown. In this study, we isolated and characterized an AP1 ortholog, DOAP1, from Dendrobium Chao Praya Smile. DOAP1 was highly expressed in reproductive tissues, including inflorescence apices and flowers at various developmental stages. Overexpression of DOAP1 resulted in early flowering in Arabidopsis, and was able to rescue the floral organ defects of Arabidopsis ap1 mutants. Moreover, we successfully created transgenic Dendrobium Chao Praya Smile orchids overexpressing DOAP1, which displayed earlier flowering and earlier termination of inflorescence meristems into floral meristems than wild-type orchids. Our results demonstrate that DOAP1 plays an evolutionarily conserved role in promoting flowering and floral meristem specification in the Orchidaceae family.

Highlights

During the floral transition in flowering plants, the vegetative shoot apical meristem that produces leaves is transformed into the inflorescence meristem that produces flowers
Agrobacterium-mediated gene transformation system based on methionine sulfoximine (MSO) selection coupled with in vitro orchid culture system (Yu et al, 2001; Hee et al, 2007; Sim et al, 2007; Ding et al, 2013) to study the biological function of a newly isolated AP1 ortholog, DOAP1, from Dendrobium Chao Praya Smile
Our findings have provided several pieces of evidence to support that DOAP1 plays a conserved role in promoting the floral transition and specifying the identity of perianth floral organs

Summary

INTRODUCTION

During the floral transition in flowering plants, the vegetative shoot apical meristem that produces leaves is transformed into the inflorescence meristem that produces flowers. This process is controlled by flowering regulatory networks in response to various environmental and endogenous signals, and the underlying molecular mechanisms have been intensively studied in the model plant Arabidopsis thaliana. Raf.) (Sun et al, 2014), Birch (Betula platyphylla) (Huang et al, 2014) and poplar (Populus tomentosa) (Chen et al, 2015) Through mainly examining their expression patterns and their effects on heterologous systems, most of these genes have been suggested to affect either the flowering process or floral organ formation. Our results suggest that DOAP1 may play a conserved role in promoting flowering and floral meristem development in the Orchidaceae family

MATERIALS AND METHODS

RESULTS

DISCUSSION