Murch, Susan , Tomlinson, P. Barry. .
Chemical composition of pollination drops in Gnetum gnemon (Gnetales) Suggests Gender Differences.
Introduction. Pollination drops (Pds) are secreted by the exposed ovule in the majority of extant "gymnosperms" as the site of reception for wind-borne pollen. Pds apparently existed in many extinct groups of seed-plants. Pds are characteristic of all three genera in the Gnetales, but insects may be the usual vector. In Gnetum gnemon trees are dioecious but the strobili of each gender possess ovules. Only female plants produce viable seed. Both male and female ovules secrete a Pd but the function of the Pd in male trees has not been defined; it may function as an attractant or reward for pollinators. Pollinators (moths in other species of Gnetum) would be required to visit separate trees of the two gender types for successful pollen transfer. Pds then could be seen as a step towards animal pollination as seen in flowering plants. Methods. Pollen drops were collected from intact trees and cut branches from late January - March, 2009 at the Kampong Garden, Miami,Fla. Female trees set abundant viable seed, but insect visitors were not observed in either day or night studies. Results and Discussion. Male and female Pds of Gnetum gnemon were chemically distinct and separated by gender in PCA analysis. Male Pds were also chemically richer than the female drops, containing 2516 distinct putative metabolites as compared with 2139 putative metabolites in the female Pds. The majority of the metabolites characteristic of male Pds fell within the polarity and molecular weight range indicative of indoles, flavonoids and polyphenols. Additionally, male Pds contained complete profiles of common protein amino acids while female Pd did not contain detectible levels of many of the amino acids. Conclusion. Differences in the chemical composition of Pds may indicate different functions of the ovulesin the two types of strobili such that males may extend the period over which a pollinator remains on any strobilius and females may deter lengthy visits to any one ovule.
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1 - University of British Columbia, Chemistry, 3333 University Way, Kelowna, BC, V1V 1V7, Canada
2 - National Tropical Botanical Garden, The Kampong, 4013 Douglas Rd, Miami, FL, 33133, USA
Presentation Type: Poster:Posters for Topics
Location: Khorassan Ballroom/Chase Park Plaza
Date: Monday, July 11th, 2011
Time: 5:30 PM