title: PnMADS1, encoding an StMADS11-clade protein, acts as a repressor of flowering in Pharbitis nil.
abstract: We previously isolated PnMADS1, a MADS-box transcription factor and member of the functionally diverse StMADS11 clade of the MADS-box family, from Pharbitis nil, which is a typical SD plant. However, its precise function remained unclear. To investigate the biological role of PnMADS1, and especially its involvement in flowering, we constructed transgenic P. nil plants that overexpresses or underexpresses PnMADS1. PnMADS1-RNAi transformants had an increased number of flower buds, whereas overexpression of PnMADS1 led to a decrease in the number of flower buds, although both transgenic plants maintained the photoperiodic responses of flowering. These results suggest that PnMADS1 negatively regulates floral evocation from the vegetative phase to the reproductive phase but it has no essential role in floral induction by photoperiodic signals. Results of yeast two-hybrid experiments revealed that PnMADS1 can interact with itself, suggesting that this protein functions in floral evocation as a homodimer. PnMADS1 also interacts with PnSAH3, an AP1-clade protein, suggesting that PnMADS1 has a functional role in flower formation as a heterodimer with other MADS-box protein(s).
authors.affiliation: Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8572, Japan. riekikuc@affrc.go.jp
authors.forename: Rie
authors.initials: R
authors.lastname: Kikuchi
authors.forename: Kimiyo
authors.initials: K
authors.lastname: Sage-Ono
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kamada
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Handa
authors.forename: Michiyuki
authors.initials: M
authors.lastname: Ono
mesh_terms: D035264:Flowers / Q000235:genetics / Q000502:physiology*; D018506:Gene Expression Regulation, Plant; D049915:Ipomoea nil / Q000235:genetics / Q000502:physiology*; D026161:MADS Domain Proteins / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified; D011485:Protein Binding; D034622:RNA Interference; D012097:Repressor Proteins / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014170:Transformation, Genetic; D020798:Two-Hybrid System Techniques
chemical_list: D026161:MADS Domain Proteins; D010940:Plant Proteins; D012097:Repressor Proteins