title: Duplicated C-class MADS-box genes reveal distinct roles in gynostemium development in Cymbidium ensifolium (Orchidaceae).
abstract: The orchid floral organs represent novel and effective structures for attracting pollination vectors. In addition, to avoid inbreeding, the androecium and gynoecium are united in a single structure termed the gynostemium. Identification of C-class MADS-box genes regulating reproductive organ development could help determine the level of homology with the current ABC model of floral organ identity in orchids. In this study, we isolated and characterized two C-class AGAMOUS-like genes, denoted CeMADS1 and CeMADS2, from Cymbidium ensifolium. These two genes showed distinct spatial and temporal expression profiles, which suggests their functional diversification during gynostemium development. Furthermore, the expression of CeMADS1 but not CeMADS2 was eliminated in the multitepal mutant whose gynostemium is replaced by a newly emerged flower, and this ecotopic flower continues to produce sepals and petals centripetally. Protein interaction relationships among CeMADS1, CeMADS2 and E-class PeMADS8 proteins were assessed by yeast two-hybrid analysis. Both CeMADS1 and CeMADS2 formed homodimers and heterodimers with each other and the E-class PeMADS protein. Furthermore, transgenic Arabidopsis plants overexpressing CeMADS1 or CeMADS2 showed limited growth of primary inflorescence. Thus, CeMADS1 may have a pivotal C function in reproductive organ development in C. ensifolium.
authors.affiliation: Institute of Biotechnology, National Cheng Kung University, Tainan 701, Taiwan.
authors.forename: Shih-Yu
authors.initials: SY
authors.lastname: Wang
authors.forename: Pei-Fang
authors.initials: PF
authors.lastname: Lee
authors.forename: Yung-I
authors.initials: YI
authors.lastname: Lee
authors.forename: Yu-Yun
authors.initials: YY
authors.lastname: Hsiao
authors.forename: You-Yi
authors.initials: YY
authors.lastname: Chen
authors.forename: Zhao-Jun
authors.initials: ZJ
authors.lastname: Pan
authors.forename: Zhong-Jian
authors.initials: ZJ
authors.lastname: Liu
authors.forename: Wen-Chieh
authors.initials: WC
authors.lastname: Tsai
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics; D015152:Blotting, Northern; D015139:Blotting, Southern; D035264:Flowers / Q000166:cytology / Q000235:genetics* / Q000254:growth & development* / Q000648:ultrastructure; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D020131:Genes, Duplicate / Q000235:genetics*; D017343:Genes, Plant / Q000235:genetics*; D026161:MADS Domain Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D029595:Orchidaceae / Q000166:cytology / Q000235:genetics* / Q000254:growth & development* / Q000648:ultrastructure; D010802:Phylogeny; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified; D011485:Protein Binding; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
chemical_list: D026161:MADS Domain Proteins; D010940:Plant Proteins; D012333:RNA, Messenger