1. 8 conventional Petri dishes containing 0.8% agar

1
The Effects of Oil Contamination on Root Growth
of Arabidopsis Matt Steelman, Josh Fester,
Tinus Van Wyk, and Nicole SowersWofford College,
South Carolina
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.
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.
Germination Overall, germination was unaffected
by oil dissolved in the agar (p0.667, ?2 with 6
degrees of freedom 4.08).
Root Growth Overall, root growth in the plant
decreased as the concentration of oil in the agar
increased (p0.001, Analysis of Variance FdF 3,
70 6.054. At 0.01, root growth was not
significantly different from the control group.
The addition of motor oil into the agar for
Arabidopsis thaliana ecotype Columbia will
significantly stunt the growth of the plants
root.
Root Growth vs. Concentration
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. 375-382.
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.