Flower development of Phalaenopsis orchid involves functionally divergent SEPALLATA-like genes.
Bottom Line: 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 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.
Affiliation: Department of Life Sciences, National Cheng Kung University, Tainan, 701, Taiwan.Show MeSH
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Mentions: Unexpectedly, the average poor dimeric interactions formed between PeSEP and other MADS-box proteins were not consistent with the role of SEP proteins as a glue to mediate complex assembly. These heterodimers may have unstable binding abilities relative to the trimeric protein complexes bridged by SEP proteins. We therefore tested whether the PeSEP proteins can function as a glue to mediate and strengthen the interactions between PeMADS6 (PI-like) and other MADS-box proteins (PeMADS2 and PeMADS4, AP3-like and PeMADS7, STK-like) by co-transforming three constructs in yeast. The original weak interactions between PeSEPs and PeMADS2, PeMADS4, PeMADS6 and PeMADS7 were greatly enhanced to strong and very strong levels (Fig.4a,b) with the formation of PeSEP/PeMADS6/PeMADS2, 4 and 7 complexes. Heterotrimerizations were revealed by facilitating the interaction among the three Phalaenopsis MADS-box proteins in PI-like/SEP-like/AP3- or STK-like complexes mediated by PeSEP proteins.
Affiliation: Department of Life Sciences, National Cheng Kung University, Tainan, 701, Taiwan.