Ickert-Bond, Stefanie M. , Rydberg, Anders , Bolinder, Kristina , Han, Jun , Jesse, Susannah , Little, Stefan , Loera Carrizales, Israel , Rydin, Catarina , Von Aderkas, Patrick .
Chemical composition of pollination drops in Ephedra - safe sex and other oddities.
Although pollination drop mechanisms are known from several extinct seed plants, within extant gymnosperms it is restricted to four clades: conifers, Ginkgo, cycads and Gnetales. Within conifers pollination mechanisms are highly variable due to varied orientations of the ovule during pollination, presence, modification or absence of the pollination drop mechanism, and whether the pollen is saccate or non-saccate. In Gnetales the ovules are orthotropous and produce pollination drops to capture non-saccate pollen. The pollination drop then retracts, carrying the pollen into the ovule. Ephedra pollination drops are produced via nucellar secretion and are presented at the tip of a long micropylar tube, an extension of the integument. Analysis of the chemical composition of pollination drops might give clues to understanding plant-insect associations involving gymnosperms and their nectarivores, pollinivores and pollinators. While most gymnosperm pollination drops contain low concentrations of sucrose (5-10 %), in Ephedra helvetica sucrose is not only the predominant sugar, but it is found at high concentrations (~ 25 %). This goes in concert with the lack of invertases in the pollination drop of Ephedra. As is typical of other gymnosperms, the protein composition of pollination drops in Ephedra includes several defense-related proteins. Since Ephedra ovules are exposed to the environment and vulnerable to potential pathogens during the time of pollen receptivity, a potential role of these proteins would be to protect the young ovule from airborne microbes - itís a safe sex mechanism. Based on a proteomic evaluation of pollination droplet proteins in several species of Ephedra we discuss implications for the evolution of pollination biology in Ephedra.
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NSF ATOL - Gymnosperms on the Tree of Life: Resolving the Phylogeny of Seed Plants
1 - University of Alaska, UA Museum of the North Herbarium & Dept. of Biology and Wildlife, 907 Yukon Dr., Fairbanks, Alaska, 99775, USA
2 - Uppsala University, Evolutionary Biology Centre, Norbyvšgen 18D, SE-75236 Uppsala, Sweden
3 - University of Victoria, Genome BC Proteomics Centre, Vancouver Island Technology Park, #3101-4464 Markham St, Victoria, BC, V8Z 7X8, Canada
4 - University Of California Davis, Department Of Plant Sciences, Davis, CA, 95616-8515, USA
5 - Instituto De Ecologia, A. C., Biologia Evolutiva, Apartado Postal 63, Xalapa, Veracruz, 91000, Mexico
6 - University of Victoria, Graduate Centre for Forest Biology, Department of Biology, P.O. Box 3020, Station CSC, Victoria, BC, V8W 3N5, Canada
Presentation Type: Oral Paper:Papers for Topics
Location: Waterman Room/Chase Park Plaza
Date: Monday, July 11th, 2011
Time: 4:15 PM