1. The Effects of Oil Contamination on Root Growth of Arabidopsis Matt Steelman, Josh Fester, Tinus Van Wyk, and Nicole Sowers Wofford College, South Carolina
Introduction
Results
Discussion
Some Arabidopsis ecotypes such as those from Ireland and Bulgaria grow on roadsides where petroleum runoff could affect their growth. In an experiment using phenanthrene as the pollutant, Arabidopsis plants were shown to be negatively affected 1. Our purpose is to investigate to what extent, if any, the root growth of Arabidopsis is affected by soil contamination with motor oil. In this experiment, we used Ecotype Columbia because it is the most commonly used ecotype in lab studies. Also, we chose our concentrations of motor oil in agar with the desire to avoid killing the plant while providing adequate variation.
Germination
Overall, germination was unaffected by oil dissolved in the agar (p=0.667, χ2 with 6 degrees of freedom = 4.08).
First of all, germination is not affected by motor oil in agar, suggesting that environment is less important than conditions inside the seed for germination. Secondly, our results support the hypothesis that an increased concentration of motor oil in agar stunts root growth. Although there was a small increase in growth from 0% oil to 0.01% oil, this increase is not statistically significant enough to disprove the alternate hypothesis. In general, root growth is negatively affected by increased concentrations of motor oil.
Implications of This Experiment
Based on this experiment, a fresh perspective on pollution can be attained. The results of this experiment show that, while plants can tolerate low levels of motor oil pollution, increased concentrations are detrimental to plant life. Therefore, we must find ways to avoid, if possible, extensive use of motor oil which pollutes the earth, or, if nothing else, to prevent disasters such as oil spills from occurring within our society.
Future Experiments
We recommend that future experiments find a more effective way to measure the root such as taking it out of the agar. Also, the experimenter must make sure that light is evenly distributed to each agar plate. Another issue that should be addressed is clumping of motor oil in the agar, for this allows the root to perhaps avoid the pollution. Finally, effects of the motor oil in agar may be different than those in soil, so perhaps soil should be used in a follow-up experiment. In regards to results, the next step to this experiment could be to find the lethal concentration of oil for this plant, for this could help us gauge the severity of our current pollution levels.
Root Growth
Overall, root growth in the plant decreased as the concentration of oil in the agar increased (p=0.001, Analysis of Variance FdF= 3, 70 = At 0.01%, root growth was not significantly different from the control group.
Hypothesis
The addition of motor oil into the agar for Arabidopsis thaliana ecotype Columbia will significantly stunt the growth of the plant’s root.
Root Growth vs. Concentration
Methods
1. 8 conventional Petri dishes containing 0.8% agar
2. 80 Arabidopsis (ecotype- Columbia) seeds
3. 5w-30 motor oil
4. Image J Software
5. Agar
6. Fluorescent Grow Lights
0%, 0.01%, 0.1%, and 1% petroleum in agar were mixed. We then planted 10 seeds of Arabidopsis in each of eight Petri dishes; 2 dishes for each concentration . We planted these seeds at the upper edge of the agar on each of the plates. Agar was used rather than soil so that we could measure the roots without removing the plant from its foundation. The dishes were sealed and vertically placed beneath fluorescent grow lights at a distance of 33cm throughout the experiment. The dishes with 0% motor oil in agar acted as the control group, while the other six had the variant concentrations of the petroleum product. Each of the plates had equal photoperiods, which were 16 hours of light and 8 hours of darkness. For two weeks, we measured the length of the roots each week. The root length was measured using Image J software (see picture below). With this software, we were able to accurately see and measure by using scanned pictures of each Petri dish.
1) Lui, Hong. “An oxidative stress response to polycyclic aromatic hydrocarbon exposure is rapid and complex in Arabidopsis thaliana.” Plant Science: Vol. 176 Issue 3 March 2009 pg
Refrences
Special thanks to GR Davis and C. Abercrombie for their assistance with statistical analysis and answering of questions. Also, thanks to A. Steadman and T. Player for their comments and suggestions.
Acknowledgements