Abstract Detail

Developmental and Structural Section

Aeilts, Luke [1], Altrichter, Kristine [1], Taylor, Mackenzie L. [1].

Pollen structure and development in Ruppia maritima (Alismatales).

Ruppia maritima L. is an aquatic plant found in shallow lakes and coastal areas throughout the world. As a member of the early-divergent monocot lineage Alismatales, Ruppia is of interest in studies of character evolution in monocots, including studies of reproductive traits. The objective of this study was to characterize pollen structure and development in R. maritima. Pollen morphology and exine ultrastructure were documented at the sporogenous tissue, microspore mother cell, tetrad, free microspore, and mature pollen grain stages using light, scanning electron, and transmission electron microscopy. Pollen characters such as exine ultrastructure and tetrad geometry, as well as timing of pollen wall development and tapetal activity, will be discussed. In R. maritima, numerous pollen grains develop within each locule. Mature pollen grains exhibit a heteropolar exine that is reticulate near the center of the proximal wall and atectate at the ends and along the distal surface. All regions of the wall exhibit a thin, contiguous foot layer, an endexine, and a fibrous intine layer. A prominent layer of tapetal exudate surrounds the exine. During development, tetragonal and decussate tetrads were observed, which is indicative of successive microsporogenesis. The tapetum is plasmodial and surrounds developing tetrads. In early tetrads, sporopollenin is first deposited in globular aggregations along the plasmalemma in both the proximal and distal walls. Ruppia exhibits epihydrophilous pollination in which pollen grains float in “pollen rafts” on the water surface until they contact a receptive stigma. This pollination strategy has consequences for reproductive traits, including pollen characters, in Ruppia. Functional correlations between pollen characters and water pollination in Ruppia maritima will be discussed.

1 - Creighton University, Department Of Biology, 2500 California Plaza, Omaha, NE, 68178, USA

Keywords:
Alismatales
exine ultrastructure
hydrophily
pollen
Pollen development
Ruppiaceae
water pollination.

Presentation Type: Poster:Posters for Sections
Session: P
Location: Eyrie/Boise Centre
Date: Monday, July 28th, 2014
Time: 5:30 PM
Number: PDS008
Abstract ID:678
Candidate for Awards:Developmental and Structural Section best poster