| Summary: | 碩士 === 國立中興大學 === 生物科技學研究所 === 102 === Proper timing of the transition from vegetative stage to flowering is critical to the reproductive success of plants. The floral transition in Arabidopsis is regulated by four flowering pathways: the photoperiod, vernalization, autonomous, and gibberellin dependent pathway. SUPPRESSOR OF OVEREXPRESSION OF CO1 (SOC1) encodes a MADS-box protein that plays an essential role in integrating multiple flowering signals to regulate the transition from vegetative to reproductive development in the model plant Arabidopsis. To investigate the function of its homologue in Orchid, we cloned OnSOC1 from Oncidium Gower Ramsey. In this study, further functional analysis of the OnSOC1 in transgenic Arabidopsis was performed. The flowering time was promoted in 35S::OnSOC1 and 35S::OnSOC1-VP16 (fused an activation domain) transgenic plants whereas 35S::OnSOC1-SRDX (fused a repressing domain) caused the delay of flowering. These results indicated that OnSOC1 acted as an activator in promoting flowering in transgenic Arabidopsis. The promotion of flowering time in 35S::OnSOC1 Arabidopsis was due to the up-regulation of AGL24 and LEAFY expression. Furthermore, similar to SOC1, OnSOC1 could form heterodimers with Arabidopsis AGL24. 35S::OnSOC1-SRDX also caused significant delay of flower senescence and abscission in transgenic Arabidopsis. Our results revealed that SOC1-like genes play an evolutionarily conserved role in promoting flowering in the Orchidaceae family. Thus, OnSOC1 isolated from Oncidium Gower Ramsey could be used as an important target for genetic manipulation of flowering time in Orchid.
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