Abstract Detail

Evolutionary Developmental Biology (Evo-Devo)

Gomez , Francisco E [1], Jordon-Thaden , Ingrid Eastman [2], Soltis, Pamela [3], Soltis, Douglas [4].

Do Polyploid Species (Tragopogon - Asteraceae) have Altered Fitness?

This study seeks to understand how ploidy level alters plant fitness in Tragopogon species, through phenotypic variation in diploid parents compared to their natural, and synthetic allotetraploid progeny. Six species of Tragopogon were part of this study: The diploid parents, T. dubius, T. pratensis, and T. porrifolius, and three recently formed allotetraploid species (naturally occurring and synthetically produced T. miscellus and T. mirus, and the synthetically produced T. floridana). Tragopogon seeds(diploid 2n=12 and tetraploid 4n=24) were germinated in October 2010. Seedlings were transplanted, and grown in an environmentally controlled chamber using a randomized block design over 20+ months. Measurements of photosynthesis rate, transpiration efficiency, mineral content (C, N, and P), growth rate, and reproductive fitness were measured. In this report we show data on mineral content, growth rate, and transpiration efficiency. Total carbon, nitrogen and phosphorus were determined on mature leaves. Leaf number was determined by counting every leaf per plant at six dates in the early stages of development. We used photosynthetic carbon assimilation (μmolCO₂/ m²s) and transpiration measures (mol H₂O) from a LI-6400XT® Portable Photosynthesis System (Licor,Nebraska) to calculate photosynthetic rate and transpiration efficiency. Data was subjected to analysis of variance, LSMeans, linear regression, and homogeneity of slope using JMP/SAS version 9.0.2. Results strongly indicated that diploids had significantly higher (p=0.0154*) nitrogen content in leaves than polyploids (0.11 vs 0.09 mg/g dm). Orthogonal contrasts among species showed that T. dubius had significantly higher (p=0.0001*) content of N (0.1355 mg/g dm) and phosphorus(p<0.0001*) (4.66 mg / g dm). No significant differences were detected for carbon, and phosphorus content for the other species. Interestingly, the ratio of C:N was significantly higher (p = 0.0011*) for polyploids (14.23 vs. 11.30)compared to diploids . There were highly significant differences between ploidy levels (<0.0001*) for number of leaves per day produced. Diploid species produced 0.37 leaves per day, while polyploids produced only 0.24 leaves per day. T. dubius produced the highest number of leaves (0.43) than the rest of the Tragopogon species within this time period. We found significant differences among Tragopogon species at (p<0.1230)for the transpiration efficiency. T. miscellus and T. mirus were significantly different from each other (7.86vs. 7.13 μmolCO₂/ m²s) for transpiration efficiency.We conclude that ploidy level does alter the nitrogen content, C:N ratio, leaf production rate and transpiration efficiency. These alterations were more pronounced in the diploid T. dubius.

Broader Impacts:

1 - University of Florida, Agricultural Biological Engineering, 20 SW 6th Street Apt # 108, Gainesville, FL, 32601, United States
2 - University Of Florida, Biology, Bartram-Carr Hall, POBox 118525, Gainesville, FL, 32605, USA
3 - University Of Florida, Florida Museum Of Natural History, PO BOX 117800, Gainesville, FL, 32611-7800, USA, 352/273-1964
4 - University of Florida, Biology and Florida Museum of Natural History, Gainesville, FL, 32605, USA

Keywords:
Tragopogon
diploids
polyploids
fitness.

Presentation Type: Poster:Posters for Topics
Session: P
Location: Battelle South/Convention Center
Date: Monday, July 9th, 2012
Time: 5:30 PM
Number: PEV002
Abstract ID:990