The Phalaenopsis orchid produces complex flowers that are commercially valuable, which has promoted the study of its flower development. E‐class MADS‐box genes, SEPALLATA (SEP), combined with B‐, C‐ ...and D‐class MADS‐box genes, are involved in various aspects of plant development, such as floral meristem determination, organ identity, fruit maturation, seed formation and plant architecture. Four SEP‐like genes were cloned from Phalaenopsis orchid, and the duplicated PeSEPs were grouped into PeSEP1/3 and PeSEP2/4. All PeSEPs were expressed in all floral organs. PeSEP2 expression was detectable in vegetative tissues. The study of protein–protein interactions suggested that PeSEPs may form higher order complexes with the B‐, C‐, D‐class and AGAMOUS LIKE6‐related MADS‐box proteins to determine floral organ identity. The tepal became a leaf‐like organ when PeSEP3 was silenced by virus‐induced silencing, with alterations in epidermis identity and contents of anthocyanin and chlorophyll. Silencing of PeSEP2 had minor effects on the floral phenotype. Silencing of the E‐class genes PeSEP2 and PeSEP3 resulted in the downregulation of B‐class PeMADS2‐6 genes, which indicates an association of PeSEP functions and B‐class gene expression. These findings reveal the important roles of PeSEP in Phalaenopsis floral organ formation throughout the developmental process by the formation of various multiple protein complexes.
碩士
國立臺灣大學
植物科學研究所
103
The mechanism of flowering and phase transition from vegetative to reproductive stage is still not well-known in Oncidesa. Our previous study has shown that three SPL (SQUAMOSA ...PROMOTER BINDING PROTEIN-LIKE) genes in Oncidesa (OgSPLs) are identified as key regulators in the phase transition of reproductive process and high ambient temperature-induced flowering, which relate to induction of the down-stream floral genes, such as FLOWERING LOCUS T (FT), APETALA1 (AP1). To comprehend the regulatory mechanism between OgSPLs and the floral genes, we cloned OgFT, OgLEAFY (OgLFY), OgAP1, and OgSPLs promoter. Our results showed that OgSPLs localizes in nucleus and could regulate OgFT, OgAP1 promoter but not OgLFY promoter. Additionally, OgFT localizes in nucleus and cytoplasm which could interact with AtFD and further regulate OgSPLs promoter. Moreover, we generated Arabidopsis transgenic plants which has GUS reporter gene driven by the target genes’ promoter of Oncidesa. GUS staining data reveal
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