Abstract Detail

Paleobotanical Section

Le , Thien-Y  [1], Dunn, Regan [1], Stromberg, Caroline [2].

The Effects of Light Quantity on Grass Epidermal Cell Shape.

Phytoliths, microscopic plant silica bodies, inform us about the types of plants that remain in the fossil record, allowing for reconstruction of past ecosystems. Phytoliths are produced abundantly in grasses, and their variation in epidermal cell wall undulation (waviness) might allow us to infer the structure of ancient vegetation (open habit vs. closed canopy). We looked at the effects of sunlight variation on epidermal cell shapes of modern grasses as a first step in creating a proxy for determining habitat type from the fossil record. Long and short cells of five species of grasses (Chusquea culeou 'Gigantea'(CC), Poa secunda (PS), Schizachyrium scoparius (SS), Sporobolus asper (SA), and Stipa viridula (SV))were grown in 20%, 60%, 100% (control), and 120% light. Morphometric measurements of individual long and short cells were made from epidermal peels using Adobe Photoshop. For each cell, the degree of waviness was calculated using the undulation index (UI), a dimensionless value representing the ratio of the circumference of the measured cell to the circumference of a circle with the same area. Silicified cells were extracted from the leaves so that heights of the short and long cells can also be examined. Data for SS, SA, and SV long and short cells, and PS short cells showed that light quantity does have an effect on UI of epidermal cells, but that the pattern between treatments can be non-linear, especially for short cells. Although there are overall statistical differences in UI between light treatments in both species and types of cells, data from SS, SA, and SV long cells show the greatest promise for use in the fossil record because of the bimodal distribution of UI between the deep shade (20% light) and enhanced light (120% light) treatments.

Broader Impacts:

1 - University of Washington, Biology, 24 Kincaid Hall, Box: 351800, Seattle, WA, 98195-1800, USA
2 - University of Washington, Biology, 24 Kincaid Hall, Box 351800, Seattle, WA, 98195-1800, USA

Keywords:
grasses
phytolith
undulation index
Light
cell shape
epidermal cells.

Presentation Type: Oral Paper:Papers for Sections
Session: 12
Location: Lindell C/Chase Park Plaza
Date: Monday, July 11th, 2011
Time: 2:15 PM
Number: 12004
Abstract ID:567