| Summary: | 碩士 === 朝陽科技大學 === 生物技術研究所 === 97 === Although light and temperature affect the flowering time in Phalaenopsis, the molecular mechanism of flowering in such floral crop remain unclear. Possible flowering-time pathways are mainly studied in Arabidopsis. To have a better understanding on the photoperiodic flowering of Phalaeanopsis, this studies started with a circadian controlled gene GIGANTEA(GI) in Phalaenopsis bellina. According to the gene homology and 5’ and 3’ RACE, the full-length of PbGI (3,480 bp) has been cloned and bioinformatically analyzed. The deduced amino acid sequences, composition and phylogenic analysis indicated that PbGI is more closed to rice GI (OsGI) and shared more than 69% of similarity with other GI homologues. PbGI is predicted to have five transmembrane regions like other GI homologues, meanwhile the cluster and correspondence analysis of its RSCU values are more similar to AtGI’s. By Southern blots and real-time PCR analysis, it was found that PbGI, a single copy gene like HvGI and OsGI, is controlled by light conditions and can express constantly in almost all tissues, especially in mature leaves and petals. Therefore, PbGI must be a GI homolog. On the other hand, an activation-tagged strategy was used to study the flowering time in Phalaenopsis, and one of the 30 transgenic Phalenopsis was observed with a delayed flowering phenotype. Such change might caused by a single insertion of pTAG-8 or other factors that remained to be studied.
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