Ralph McNeilage, Botany & Mycology 2009 Poster Session Interviews

Fertilization timing and pollen tube growth in Nymphaea (Nymphaeales). Co-authors: Mackenzie L. Taylor, and Joseph H. Williams.

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.

Category:

Science & Technology

Tags:

• Ralph McNeilage
• botany
• conference
• plant
• biology
• science
• fertilization
• Nymphaea
• Nymphaeales
• progamic phase
• pollination
• angiosperm
• flower morphology
• water lily
• gametophyte
• pollen germination
• pollen tubes
• Joseph H. Williams
• Mackenzie L. Taylor

[1091Floyd21]

At what point does the microspore become known as the pollen grain? Is it as soon as the microspore mother cell has divided by meosis to produce the microspores, that they are considered pollen grains OR is it when division by mitosis occurs producing the generitive & tube cells enclosed by a thick, that it is considered to be a pollen grain.