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: Four SEP-like genes isolated from P. equestris were named PeSEP1,PeSEP2,PeSEP3 and PeSEP4 (GenBank KF673857–KF673860, Table S4). The reconstructed phylogeny suggested that these four P. equestris SEPs, together with all available orchid SEP homologs, formed two separate monophyletic clades, in which PeSEP2 and PeSEP4 grouped to the orchid SEP1/2 (in the AGL2/3/4 or SEP1/2/4 clade), with PeSEP1 and PeSEP3 included in the orchid SEP3 (in the AGL9 or SEP3 clade) (Fig.1). Therefore, apart from the major pre-angiosperm gene duplication event separating AGL2/3/4 and AGL9 clades, additional SEP duplications within the monocots and orchids were evident (blue bars in Fig.1). Similar additional duplication events also pre-dated the rosid and asterid diversification within their lineages. All predicted amino acid sequences of PeSEP proteins shared 61–82% identity and 76–89% similarity, and possessed the conserved MIK domain and a divergent C-terminal domain with the conserved SEP I and SEP II motifs, whereas PeSEP2 has a partial deleted form of the SEP Imotif (Figs2a, S2).
Affiliation: Department of Life Sciences, National Cheng Kung University, Tainan, 701, Taiwan.