Molecular cloning and spatiotemporal expression of an APETALA1/FRUITFULL-like MADS-box gene from the orchid (Cymbidium faberi).

Abstract

In order to identify genes involved in floral transition and development of the orchid species, a full-length APETALA1/FRUITFULL-like (AP1/FUL-like) MADS box cDNA was cloned from Cymbidium faberi (C. faberi) sepals and designated as C. faberi APETALA1-like (CfAP11], JQ031272.1). The deduced amino acid sequence of CfAP11 shared 84% homology with a member of the AP1/FUL-like group of MADS box genes (AY927238.1, Dendrobium thyrsiflorum FUL-like MADS box protein 3 mRNA). Phylogenetic analysis shows that CfAP11 belonged to the AP1/FUL transcription factor subfamily. Bioinformatics analysis shows that the deduced protein had a MADS domain and a relatively conservative K region. The secondary structure of CfAP11 mainly consisted of alpha helices (58.97%), and the three-dimensional structure of the protein was similar to that of homologues in Roza hybrida, Oryza sativa and Narcissus tazetta. Real-time quantitative PCR (qRT-PCR) results reveal low levels of its mRNA in roots, lower levels in leaves during reproductive period than vegetative period, and higher levels in pedicels at full-blossom stage than at bud stage. These results suggest that CfAP11 is involved in floral induction and floral development. Additionally, we observed higher levels of CfAP11 expression in pedicels and ovaries than in other tissues during full-blossom stage, which suggests that CfAP11 may also be involved in fruit formation in certain mechanism.