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: The polygonal-shaped epidermis on the adaxial side became flattened and changed from a papillae/cupola/conical to hemispherical shape in sepals and petals (Fig.7b,d,j,l) of PeSEP3- and PeSEP2/3-silenced flowers, accompanied by an increased aspect ratio Î² (Fig.6e). When compared with the convex-shaped epidermal cells on the abaxial surface of the sepal and petal in mock-treated flowers (Fig.7e,m), cells in PeSEP3- and PeSEP2/3-silenced flowers were flat (Fig.7f,h,n,p). In addition, PeSEP-silenced flowers showed a protuberance in the central field of the petal epidermis on the abaxial side (arrows in Figs7n,p, 8i) that resembled leaf abaxial epidermal cells (Fig.7z). Moreover, several microgranules were secreted from the epidermis on the adaxial side of the sepal and petal in PeSEP-silenced flowers (Fig.7bâ€“d,jâ€“l), unlike the smooth surface of the epidermis in mock-treated flowers (Figs7a,i, 8a,b). These microgranules covered the protuberance and sometimes appeared in the central field of the epidermis (Fig.8c,d). Furthermore, the greatly accumulated microsecretory granules on the protuberance of the adaxial epidermis may have contained lipids, as seen on histochemistry with Sudan IV staining (Fig.8l,o). In addition, platelet-shaped epicuticular wax crystals accumulating on the bract epidermis on the abaxial surface of mock-treated plants (Figs7y, 8j) appeared to aggregate randomly on the epidermal surface in all PeSEP2-, PeSEP3- and PeSEP2/3-silenced sepals (Figs7fâ€“h, 8h).
Affiliation: Department of Life Sciences, National Cheng Kung University, Tainan, 701, Taiwan.