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
Related in: MedlinePlus
Mentions: We investigated the expression profiles of the four PeSEP genes in Phalaenopsis (Fig.3). All four genes were expressed in the flower buds (Fig.3i). The expression of PeSEP1 and PeSEP3 was specific to reproductive tissues, whereas only the expression of PeSEP2 was detectable in vegetative tissues and significantly high in the floral stalk (Fig.3i). By contrast, PeSEP4 expression was extremely low in all tissues. Furthermore, transcripts of PeSEPs persisted throughout the entire floral development (Fig.3j). We further analyzed the expression of PeSEP1–3 in sepal, petal, lip and column; transcripts of PeSEP1–3 were widely detected in all floral organs (Fig.3k). PeSEP2 was highly expressed in the column, and PeSEP3 expression was dominant in the petal. In addition to floral organs, we analyzed transcripts of PeSEPs in developing ovules, embryos and mature seeds after pollination; the expression of PeSEP1–3 was enriched in the near-mature ovule at 56 d after pollination (DAP), but was nearly undetectable in various developing embryo stages (embryo 1, 80 DAP and embryo 2, 100 DAP) and seeds (Fig.3l). Although the PeSEP genes were produced by recent gene duplication events, they showed overall non-overlapping expression profiles, both temporally and spatially. The non-ubiquitous expression patterns of PeSEP genes suggest that these SEP genes probably have functional divergence in regulating Phalaenopsis vegetative tissue, flower and ovule development.
Affiliation: Department of Life Sciences, National Cheng Kung University, Tainan, 701, Taiwan.