Evolutionary Developmental Biology (Evo-Devo)
Mullenniex, Anne , Goetsch, Loretta , Di Stilio, Veronica , Hall, Benjamin .
Molecular Studies of Floral Evolution in Vireya Rhododendrons.
Zygomorphy is thought to have arisen independently multiple times as a specialized mechanism for pollinator interactions and may have promoted speciation and diversification. In Papuasia, the majority of species of Rhododendron L. section Vireya (Blume) Copel.f. occurring above 3000m are zygomorphic with the following characteristics: red tubular flowers with spreading corolla lobes, obliquely offset mouth with abaxial curvature of the tube, and adaxially-located stamens with style. It has been suggested that this combination of flower structure and orientation is advantageous for bird pollination; the oblique mouth protects the abaxial corolla lobes from damage and the curvature situates the reproductive structures in the optimal position for ornithophilous pollination. Representatives of four nectar-eating bird genera of the Meliphagidae occur above 3000m in Papuasia, and the curvature of their beaks and tongues mimic this corolla structure. Preliminary phylogenetic analysis of RPB2-d sequences divides the New Guinea and Queensland Vireyas into two well-supported clades. Species of subsection Phaeovireya Sleumer are paraphyletic with the zygomorphs nested within one clade and the actinomorphs found in the sister clade. To investigate the origins of asymmetry, we have initiated studies of the CYC-like genes in Rhododendron—TCP transcription factor genes known to contribute to floral asymmetry. Using a gene-walking method along with RT-PCR of cDNAs, we have characterized the complete sequences of one copy each of RhCYCL1 (i.e., Rhododendron CYCLOIDEA-like 1) and RhCYCL3 and two copies of RhCYCL2. We use RT-PCR to determine spatial and temporal expression of these CYC-like genes. Our goal is to document and understand the changes in structure, regulation and transcript localization for these genes in the context of Vireya Rhododendron evolution.
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1 - University of Washington, Department of Biology, BOX 351800, Seattle, WA, 98195, USA
2 - University of Washington, Biology, 202A Johnson Hall, Box 351800, Seattle, WA, 98195, USA
3 - University of Washington, Biology, Seattle, WA, 98195, United States
Presentation Type: Oral Paper:Papers for Topics
Date: Wednesday, July 30th, 2008
Time: 10:15 AM