Developmental and Structural Section
Taylor, Mackenzie L. , Williams, Joseph H. .
Fertilization timing and the pollen tube pathway in Cabombaceae (Nymphaeales).
Fertilization in seed plants is the result of concurrent development of four distinct entities, the male and female sporophytes and the male and female gametophytes. In angiosperms, these ontogenies are especially intertwined during the period between pollination and fertilization, the progamic phase. Relatively little is known about the progamic phase in recently defined basal angiosperms. A range of studies indicates that the Nymphaeales, or water lilies, comprise one of these earliest lineages of angiosperms. In this presentation, the pollen tube pathway in the two genera that comprise the water lily family Cabombaceae, Brasenia and Cabomba, will be characterized and the relative timing of developmental events that occur during the progamic phase will be described. These events include the duration of stigma receptivity, female gametophyte receptivity, pollen germination, ovule entry, and fertilization. Maximum pollen germination occurs within 15 min in Cabomba and 60 min in Brasenia. Pollen tubes grow at the same rate in both genera, but ovule entry was first observed after 2 hrs in Cabomba and 6 hrs in Brasenia. Stigmata are receptive the entire time the flower is open in Cabomba, while in Brasenia, the duration of receptivity is less than 4 hrs. Brasenia and Cabomba are sister genera that flower in a similar environment; however, Brasenia is wind-pollinated, while Cabomba is insect-pollinated. Divergence of pollination syndromes in Cabombaceae can explain disparity in floral structure, and has had direct and indirect effects on reproductive timing.
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1 - University of Tennessee, Department of Ecology and Evolutionary Biology, 569 Dabney Hall, Knoxville, Tennessee, 37996, USA
2 - University of Tennessee, Department of Ecology and Evolutionary Biology, 442 Hesler Biology, Knoxville, Tennesee, 37996, USA
pollen tube growth
Presentation Type: Oral Paper:Papers for Sections
Location: Boulevard C/Hilton
Date: Tuesday, July 10th, 2007
Time: 10:30 AM