Diane Cooley
Project Description
"Pollen Tube Growth in Nuphar"
Nuphar is a genus within the order Nymphaeales, or water lilies, that is found in freshwater ponds and lakes throughout the temperate Northern Hemisphere. Nymphaeales, which consists of three families (Hydatellaceae, Cabombaceae, Nymphaeaceae), is one of the oldest independent lineages of flowering plants. Because of this, reproductive traits of water lilies are of considerable interest. Nuphar is the earliest-diverging genus with the family Nymphaeaceae and lacks many of the derived traits that are found in “core” Nymphaeaceae (Victoria, Euryale, Nymphaea), such as spheroidal pollen and a united stigmatic surface. This may have consequences for pollen germination and pollen tube growth; however these processes have not been comprehensively documented in Nuphar. Flowers in Nuphar open for four consecutive days. On the first day, flowers are female with have receptive stigmas, whereas on the following days, flower are male and have dehiscent stamens. Nuphar is insect-pollinated (beetles and bees), but self-pollination potentially occurs. The goal of this study was to characterize post-pollination processes in Nuphar advena, including the timing pollen germination, pollen tube growth rates, timing of ovule entry, and the pollen tube pathway. First and second-day flowers were hand-pollinated and collected sequentially over 12 hours. Pollen grains germinated within one hour after pollination in first-day flowers. Pollen tubes reached the ovule closest to the stigma between 5 and 7 hours after pollination and the ovules at the base of the stigma within 9 hours. Average pollen tube growth rate is comparable to that of Nymphaea. Pollen also germinated on “male” second-day flowers and pollen tubes reached ovules.
Presentations
2013 Nebraska Academy of Science
2014 Creighton Biology Department Research Colloquium
2014 Creighton Biology Department Research Colloquium