Leslie, Andrew .
Testing Saccate Pollen Discrimination During Pollination in Extant Conifers.
Sacci, inflated air bladders, are a conspicuous feature of pollen grains produced by some members of the living conifer families Pinaceae and Podocarpaceae — as well as taxa in a number of extinct seed plant groups. In living conifers, sacci aid in reproduction by causing pollen grains to float upwards in a liquid droplet secreted by the ovules, which is thought to concentrate saccate pollen inside the ovule and exclude non-saccate pollen and spore grains. Evidence from laboratory experiments using model ovules and artificial pollination experiments using the living species Pinus mugo and Pinus nigra suggests that a flotation mechanism can effectively discriminate saccate and non-saccate pollen during pollination. In ovules that have received both saccate and non-saccate pollen, the secretion of a liquid droplet greatly increases the proportion of saccate grains found inside the ovule, leaving most non-saccate grains outside. This study also demonstrates the importance that the ovule integument plays in the capture of pollen during pollination in living species of Pinus. Because of the morphological similarity between saccate pollen produced by living conifers and fossil saccate pollen, insights from these pollination experiments may be used to reconstruct pollination biology in several groups of extinct seed plants and potentially provide a more complete understanding of the evolution of pollination biology in seed plants.
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1 - University of Chicago, Department of Geophysical Sciences, 5734 S. Ellis Avenue, Chicago, Illinois, 60637, USA
Presentation Type: Oral Paper:Papers for Topics
Location: Wasatch A/Cliff Lodge - Level C
Date: Monday, July 27th, 2009
Time: 4:00 PM