Evolutionary Developmental Biology (Evo-Devo)
Specht, Chelsea , Bartlett, Madelaine E. , Renner, Tanya .
Evolution of the stamen whorl in the Zingiberales.
The Zingiberales demonstrate an interesting evolutionary trend in the ontogeny of the stamen whorl. In the basal “banana families” (Musaceae, Lowiaceae, Strelitziaceae, Heliconiaceae), two consecutive stamen whorls each contain 3 fertile stamens, or a single stamen will abort early in development resulting in 5 fertile stamens at maturity. Stamens have a ‘typical’ filament and anther construction. In the derived ginger families, the number of fertile stamens is reduced to one (Costaceae, Zingiberaceae) or 1/2 (Cannaceae, Marantaceae). The fertile stamen develops from the inner stamen whorl and is petaloid. The remaining infertile stamens (“staminodes”) share positional homology with stamens of the banana families but develop as petaloid structures, taking on the function (pollinator attraction) and structure (conical epidermal cells) of petals. In Zingiberaceae and Costaceae, 2-4 or 5 (respectively) staminodes fuse together to form a novel structure, the labellum. This labellum comprises the main visual aspect of the floral display and is involved in creating the variety of pollination syndromes found in these highly diverse families. In this study, we focus on the role of the MADS-box family of transcription factors in the development of the labellum with the goal of investigating homologies of organ identity and organ position. We use a comparative candidate gene approach to identify the genes that are likely to be involved in stamen and staminode formation in Musa and in labellum formation in Costus. Combining results from studies of gene evolution across Zingiberales, comparative gene expression in Musa and Costus and VIGS-based genetic knockdowns in Zingiber, we attempt to tease apart the developmental genetic mechanisms leading to the formation of the labellum and thus driving morphological evolution and diversification in the Zingiberales.
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1 - University of California, Berkeley, Plant and Microbial Biology, 111 Koshland Hall MC 3102, Berkeley, California, 94720-3102, USA
2 - University of California, Berkeley, Plant and Microbial Biology, 111 Koshland Hall MC 3102, Berkeley, CA, 94720-3102, USA
Presentation Type: Oral Paper:Papers for Topics
Date: Wednesday, July 30th, 2008
Time: 9:00 AM