Developmental and Structural Section
McNeilage, Ralph , Taylor, Mackenzie L. , Williams, Joseph H. .
Fertilization timing and pollen tube growth in Nymphaea (Nymphaeales).
The progamic phase is the life history stage in seed plants that begins with pollination and ends with fertilization. Investigating progamic phase development in early-divergent angiosperm lineages may provide insights into the flexibility of developmental traits that coordinate the unique fertilization process in angiosperms. Nymphaeales (water lilies) is well suited among early-divergent lineages for investigations of progamic phase biology because it exhibits pollination strategies and flower morphologies that are more diverse than most other basal lineages. The objective of this study was to characterize progamic phase development in Nymphaea odorata, the American white water lily. Hand-pollinations and sequential collections of flowers (5, 10, 15, 30 minutes and every half an hour thereafter until 6 hours after pollination) were used to determine the timing of developmental events between pollination and fertilization. Pollen tube pathway, morphology, and growth, as well as timing of pollen germination and female gametophyte receptivity were documented using light and fluorescence microscopy. Pollen germination occurred within five minutes of pollen reception on a restricted area of the stigmatic surface. Pollen tubes entered the ovary by first growing exclusively through the narrow region where post-genital fusion of the carpel had occurred and then entered the secretion-filled ovarian cavity. Ovules in the uppermost portion of the ovary were penetrated first. Notably, the fastest pollen tube growth rates were recorded early in development. Female gametophytes are receptive at pollination and fertilization occurs as early as 3.5 hours after pollen reception. Nymphaea shares a rapid progamic phase, mediated by rapid pollen germination and pollen tube development, with other Nymphaeales and Hydatellaceae.
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1 - University of Tennessee , Department of Ecology and Evolutionary Biology, 569 Dabney, 1416 Circle Dr., Knoxville, Tennessee, 37996, USA
2 - University of Tennessee, Department of Ecology and Evolutionary Biology, 442 Hesler Biology, Knoxville, Tennesee, 37996, USA
Presentation Type: Poster:Posters for BSA Sections
Location: Event Tent/Cliff Lodge
Date: Tuesday, July 28th, 2009
Time: 5:30 PM