Leaves of Tradescantia zebrine, commonly called Wandering dew or Spiderwort, are widely used for investigations of stomata in the laboratory. The opening and closing of these apparatuses indicate the time of day when plants are able to carry out photosynthesis. This study aims to determine at which time of day the stomata of spiderwort leaves are either opened or closed. It is hypothesized that all stomata are open during daylight and all are closed at night. During each investigation, two leaves were obtained from each of the 3 Spiderwort plants grown in the UNG greenhouse. Five square millimeters of the underside of each leaf were cut and used as the sampling area to count the number of stomata. This was done in the morning (8ºclock), at noon (1ºclock), and evening (9 ºclock) for three different days to serve as replicates. Counting was done under a light microscope at 400x total magnification. Results showed that about 85% of the stomata are open in the morning and noon times but 15% were closed. Similarly, at night about 88% of the stomata were closed but 12% were still open. These findings rejected the hypothesis. This suggested that although most of the stomata in spiderwort behave as expected of a typical C3 plant, other factors seem to influence the timeliness of some stomata opening and closing which may have an impact on the plant’s physiology.
1 Unversity of North Georgia
P184 • Zoe Kempton1, Amanda Long1, Katie McDermott1, Valentina I. Ochoa Mendoza1, Gabriel I. Herrick1, Celina M. Bellanceau1, Neal Halstead2, An-Phong Le1
Two Species of Native Florida Butterfly Have Varying Response to Egg Deposition on Native and Non-Native Pipevine Aristolochia Spp.
During the course of breeding two species of native Florida butterflies, we have observed that Battus polydamas seems to have a wide tolerance for different species of pipevine Aristolochia sp. ), being able to feed on both native and non-native plant members of this genus. Alternatively, B. philenoreggs deposited on non-native Aristolochia results in dispersal in search of a more suitable food source and/or lower survival. These observations suggest that the larvae of these two native Florida butterfly species have differing tolerance ranges for eating native versus non-native Aristolochiaplants. Our goal is to test the hypothesis that levels of the nephrotoxic and carcinogenic aristolochic acid are higher in non-native Aristolochiaspecies, causing reduced survival in B. philenorlarvae. We are currently using HPLC to quantify the relative concentrations of aristolochic acid in four species of Aristolochiato test this hypothesis. Furthermore, we are rearing both B. polydamasand B. philenoron native and non-native species of Aristolochia. We predict greater survival and size of larvae over time, shorter time to pupation and a greater rate of successful emergence of B. philenoron the native species compared to the non-native species of Aristolochia, confirming our initial observations in the field. Results can have a positive conservation impact by highlighting the importance of propagating native Aristolochia species in Florida, which should increase viability of B. philenor populations.
1 Biology, Florida Southern College, Lakeland, FL; 2Dept of Integrative Biology, University of South Florida
P185 • Seth D. Worley1, S. Douglas Kaylor1, M. Joseph Hughes2
Stressed Fraser Fir Trees Prioritize Photosynthetic Capacity Over Other Functions
We asked if Fraser Fir (Abies fraseri) compensates for stunted needle morphology by increasing photosynthetic pigment density. Fraser fir, along with red spruce (Picea rubens), are co-dominant species in the cloud forests of the Great Smoky Mountains National Park, and are affected by a variety of stressors including acid and nutrient deposition, climate change, and the balsam wooly adelgid. Shoots in full sun were collected from 222 Fraser fir trees in 37 locations, with the different sites capturing the range of Fraser fir in the Park as well as elevational and stress gradients, with different needle morphologies observed during collection. To quantify morphology, the needles were scanned using a flatbed scanner and measured using MIMSI, a Matlab program that measures area, perimeter, length, and width of individual objects in images. The needles were then analyzed for chlorophyls a and b and carotenoid content using a methanol extraction. We found that smaller needles had more pigments per gram than larger needles, but not more pigments per unit area. This means that stunted needles have proportionally fewer non-photosynthetic compounds than healthy needles. From this we conclude that stressed trees prioritize photosynthetic capacity over secondary functions performed by other compounds.
1 Dept of Forestry, 2 Dept of Ecologt and Evolutionary Biology: University of Tennessee, Knoxville, TN
P186 • A. Calan McKinney1, M. Joseph Hughes1, S. Douglas Kaylor2
