The Effects of Drought on Arabidopsis Ecotypes Hunter Soltis, Victor Makali, Allison Poole, and Lucy Monigle

Wofford College, South Carolina

Introduction Discussion

Arabidopsis is found in almost every part of the world. Arabidopsis ecotypes have adapted to thrive in local environment, with varying climates and precipitation. Does rainfall affect the growth of three Arabidopsis ecotypes? The ecotypes selected were determined by the amount of precipitation they receive. These ecotypes are: Zloc-1 from Bulgaria, NZ1 from Hamilton, New Zealand and Can-0, from the Canary Islands, Spain. The Zloc-1 plant has adapted to a temperate environment, with regular rainfall equal to about 65 centimeters per year (http://www.wordtravels.com). The NZ1 plant has adapted to the high amounts of precipitation in its region, with more than 121.9 cm per year (www.climate-charts.com), while the Can-0 plant had adapted to thrive in a region with low precipitation, with average yearly rainfall rarely exceeding 25.4 cm (www.brittanica.com). If the plants from the different ecotypes are able to survive under drought conditions, then the durability and adaptability of the plant will be shown.

Effect of Drought on Stem Growth of 3 Arabidopsis Ecotypes

Results

Hypothesis

Simulated drought conditions will stunt stem growth in Arabidopsis.

References

www.wordtravels.comwww.climate-charts.com www.brittanica.com

Acknowledgements

We would like to thank G.R. Davis, C. Abercrombie, their assistants T. Player and A. Steadman. Our class and the rest of the Biology Department!

The experiment produced results that were similar between all groups, because of the conditions that were applied to the three different ecotypes. In the first week, the plants had similar growth because there was no difference in the soil, and the effects of the drought did not have a large effect, which was biologically unsurprising.

The second week was more biologically interesting, as the effects of both the drought conditions and the ecotypes demonstrate their adaptation to the environment and drought tolerance.

Our results supported the null hypothesis. The Arabidopsis was not negatively effected by drought conditions, but instead thrived under excess watering. Our results confirmed what is already known, that Arabidopsis can survive under diverse conditions.

For future studies, we recommend that this experiment be carried out for longer then two weeks. Drought plants should have been planted in a less water-saturated soil and watering conditions need to be consistent. Measurements for plants with irregular growth (bent or fallen) could have been taken using a string method.

18 seeds of ecotype Can-0 were placed in the soil of each of two trays, tray C-1, and tray C-2. This was repeated for ecotype NZ1 into tray N-1 and tray N-2, as well as for ecotype Zloc-1 into tray Z-1 and tray Z-2. The seeds were germinated for 2-4 days under a photoperiod of 16hrs light/8hrs dark. Plants from N-1, Z-1, and C-1 were be the control group. They were watered every other day. Plants from N-2, C-2, and Z-2 were be under drought conditions, and were not be watered. All plants were kept under the same photoperiod of 16hrs light/8hrs dark, with the temperatures kept between 20° C and 25° C. Stem lengths were measured once a week with a caliper or measuring stick.

Methods

During the first week, condition and ecotype had little effect on stem growth. During the second week however, condition and ecotype had individual effects on the growth, and there was a significant difference in growth when both ecotype and condition are taken into account.

The graph shows that stem growth was not negatively affected by drought conditions, but displayed an adaptability to varied conditions. Between the ecotypes, there was not much variability in growth, which was unexpected.

ANOVA; Effect of Drought on Stem Growth of 3 Arabidopsis Ecotypes

The Effects of Seed Depth on Germination and Plant Survival Morgan Hiler, Carrie Martin, and Hannah Leirmoe

Wofford College, South Carolina

Methods

Introduction

Discussion

These results support the original hypothesis that the seeds planted in both conditions would germinate; however, those seeds planted beneath the agar were generally not capable of breaking the surface. Therefore, in the natural habitat of the Arabidopsis if the seeds are planted rather than wind distributed the seeds will not be able to survive. This is because the seeds do not have enough stored energy to support the plant long enough for the shoot to break the surface and begin photosynthesis. The seedlings that broke the dome’s surface had a shorter distance, because they were not placed exactly underneath the middle of the dome or they moved when the domes were placed on top of the seeds. There could be several confounding factors in this experiment; such as the seeds below the agar did not receive direct light like the seeds on the surface. Some seeds could fail to germinate at all.  

All seeds germinated, so there was obviously no treatment effect on germination ( P-value was 1; Fisher’s exact test).

Seeds planted correctly beneath the dome of agar did not break the surface.

These results suggest that had the experiment continued, the plants under the agar would have eventually died.

References

(http://www.calstatela.edu/faculty/vllnwth/grow.htm)

Results

Acknowledgements

Thanks to Professors Davis and Abercrombie for their support and suggestions. Thanks also to T. Player and A. Steadman

Hypothesis

Arabidopsis seeds are planted below the surface of the agar will germinate, but the shoots will not be able to break the surface of the agar.

Week 1 Seed ScanTop to Bottom, Left to Right

1, 2,3, 4,5, 6

Week 2 Seed Scan

Top to Bottom, Right to Left

1, 2,3, 4,5, 6,

Arabidopsis seeds are wind distributed; they germinate and grow where they land on the surface of soil. In the laboratory to facilitate the measurement of shoot and root growth the seeds are grown in agar. As far as we know, there has been no previous experimentation to determine if the seeds of Arabidopsis will be able to grow when planted beneath the surface of the agar or soil. Using agar we will endeavor to answer this question.

Experiment Procedure:1. 14 seeds spaced evenly across the surface of the agar in the six Petri dishes. 2. 0.8% agar was used to make 42 small domes of agar on a flat surface.3. The domes were cooled carefully and were removed and placed on top of the seven seeds in each Petri dish.4. Dishes were sealed and labeled 1, 2, 3, 4, 5, and 6. Once sealed, the dishes were placed under a 16 hrs light and 8 hrs dark cycle under florescent lights.5. After a week seeds were checked for germination.6. After two weeks the seeds were checked again for any continued germination and if any of the seeds under the agar domes had broken the surface.

The Growth of Shoots in Arabidopsis Plants in Soil and Agar

Leah Odom, Gordon Gulledge, Becka Dunbar, and Becky GardnerWofford College

Introduction Summary

Discussion

Hypothesis

Since most plants are already planted in soils and not in agar dishes, we think that planting the seeds in soil will speed up the germination time. Many times, in research labs, Arabidopsis’ are grown in agar. However, a study done by Robert Eddy and Daniel Hahn from Purdue University showed that Arabidopsis plants can be grown in soil. Our experiment is whether soil or agar would be produce longer shoot lengths in the Arabidopsis.

If Arabidopsis seeds are planted in soil, the shoot will be longer than if planted on agar plates.

Methods

1. Ten Arabidopsis thaliana seeds of each Ecotype Columbia were planted on the upper edge of the agar in each of five different small cups. Each cup was designated by a letter and each seed in the cup was given a number so that we were able to keep track of each plant.

2. Cups covered with saran wrap were placed in a vertical position underneath florescent lighting on a 16 hour light: 8 hour dark photoperiod. This was the control group in the experiment.

3. Ten Arabidopsis seeds were also placed in each of 5 soil filled cups covered in saran wrap with the exact same photoperiod.

4. The humidity levels of both the soil and the agar plates were kept as similar as possible by covering each of the cups with saran wrap.

5. The seeds were observed once a week on Wednesday over a period of two weeks. On the first Week, we recorded germination rates of the plants and on the second week we measured the shoot length of each of the 100 plants.

6. After measuring the shoot length and recording the germination rates, we were able to use the SPSS program to run analysis of our experiment.

Results

Arabidopsis plants are found in a wide variety of environments and conditions. Planting Arabidopsis seedlings in a laboratory limits the conditions of growth and does not represent a natural environment. By planting in seedlings in soil, you are able to simulate natural environmental conditions. An advantage of planting the seedlings in agar is being able to observe the full growth of the plants. These results show that soil provides better conditions for Arabidopsis shoot growth. After comparing the results of shoot growth in agar and soil, they support our original hypothesis proving that the shoot lengths of the Arabidopsis seedlings grown in soil are significantly longer than those grown in the agar.

This experiment was fairly simplistic, only observing the germination percentage and the average shoot length. In future experiments, it would be more beneficial to incorporate different temperatures or light cycles to simulate varied environments. This would allow the scientist to more accurately determine the causes of accelerated shoot length growth.

It was found that Arabidopsis seedlings have a longer shoot when grown in soil instead of agar. On average, the seedlings grown in soil measured around 7mm while the seedlings grown in agar averaged only 4mm.

Status of Hypothesis

Acknowledgements

These results support the hypothesis that Arabidopsis seedlings planted in soil grow significantly longer shoots after two weeks than seedlings planted in agar.

Arabidopsis grown in soils shoots grew significantly longer than those grown on agar. (P=.000, ANOVA, Fdf=1,72=31.16)

Part I: Effects of Soil vs. Agar on Germination

Seeds germinated equally well on soil and in agar. (P=0.176, Fischer’s exact test) (data not shown). We have no statistically significant evidence that germination rate is associated with treatment.

Part II: Effects of Soil vs. Agar on Shoot Length

The authors are indebted to G.R.. Davis for help with data collection and to C.L. Abercrombie for help with statistical analysis.

The graph above shows the shoot length (in mm) of Arabidopsis plants, after two weeks, grown in soil and agar. The graph proves that the shoot length is significantly longer in the seedlings planted in soil. It can be said that the treatment of the seedlings has a large impact on how much they will grow.

In order to complete this experiment, we will need the following items:Four agar plates such as used in our lab over the past two weeks1. 8 agar plates 2. 40 Arabidopsis (ecotype- Columbia) seeds3. 5w-30 motor oil4. Image J Software5. Agar6. Fluorescent Grow Lights

Prior to the actual planting of the Arabidopsis, we had to mix 0.01%, 0.1%, and 1% petroleum in agar. We used these concentrations to see how growth is affected by the amount of pollution present in the soil. We limited the highest concentration to 1% in order to lower the risk of potential destruction of the plant entirely. Once this was done, we planted 10 seeds of Arabidopsis in each of four agar plates. We planted these seeds at the upper edge of the agar on each of the plates. The seeds were planted in a horizontal line , and the plates were sealed and placed vertically beneath grow lights throughout the experiment. One plate acted as the control group, and the other three 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. We produced this light cycle by setting a timer for the fluorescent light in the lab. We allowed them to germinate and mature over a period of two weeks and we measured the length of the shoots each week. The root length was measured using Image J software. These measurements provided the results for our experiment.

The Effects of Oil Contamination on Development of Arabidopsis Matt Steelman, Josh Fester, Tinus Van Wyk, and Nicole Sowers

Wofford College, South Carolina

Methods

Introduction Discussion

Some Arabidopsis ecotypes such as those from Ireland and Bulgaria are known to grow on roadsides where petroleum runoff could affect their growth. In an experiment using just phenanthrene as the pollutant, the Arabidopsis plants were shown to be negatively affected. We desired to perform a similar experiment using basic petroleum to see the effect of this on plants in our world today. This desire is based on the real-world problem that is pollution.

The results of our experiment served to support our alternate hypothesis that an increased concentration of oil in the agar would stunt the growth of the root. Although there was a small increase in growth from 0% oil to 0.1% oil, this increase is not significant enough to disprove the alternate hypothesis.

Implications of This ExperimentThe results of this experiment provide large implications for the natural world. Today, society deals with multiple forms of pollution which are destructive to the world we live in. This experiment shows that pollution in the soil due to oil spills, emissions, etc., will prove detrimental to plant life on earth. Therefore, we must find ways to avoid significant use of oil and, if nothing else, to prevent disasters such as oil spills from occurring within our society.

Future ExperimentsWe 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. The next step to this experiment could be to find the lethal concentration of oil for this plant.

Results

References

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.

Hypothesis

The Addition of petroleum into the agar for Arabidopsis thaliana ecotype Columbia will significantly stunt the

growth of the plant’s root.

Germination

Overall, germination was unaffected by increased concentration of oil dissolved in the agar (p=0.667, χ2 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 (p=0.001, Analysis of Variance FdF= 3, 70 = 6.054

Acknowledgements

Special thanks to Dr. Davis and Dr. Abercrombie for their assistance. Also, thanks to Andy Steadman and Thomas Player.

Root Growth vs. Concentration

The Effects of Agar Composition on Root Development in Arabidopsis thaliana

Matthew Boggs, Aaron Seigler, James SkinnerDepartment of Biology, Wofford College, Spartanburg, SC 29303

Indroduction

Materials and Methods

Results

Hypothesis

The greater the density of an agar solution that Arabidopsis thaliana (Columbia) seeds are cultivated in, the longer the roots.

Materials1. 6 square agar plates2. 48 Arabidopsis seeds (Columbia)3. 1 set of grow lights4. 0.40% agar for two dishes (Control Group)5. 0.80% agar for two dishes6. 1.60% agar for two dishes7. Tape8. Marker9. Agar Plate Rack10. Caliper   Methods1. Three compositions: 0.40%, 0.80%, and 1.60%.2. Two dishes with 0.40%.3. Two dishes with 0.80.4. Two dishes with 1.60%.5. 8 seeds placed in upper edge of each agar plate.6. Dishes sealed and marked accordingly. Marked with small numbers to not obstruct measurements. Tape that sealed the dishes was placed in a position that did not inhibit measurement.7. Dishes were placed under growth lights in vertical positions on an agar rack. Dishes went under light cycle of 16 hour days and 8 hour nights. 8. Measurements of root length were taken with Image J software over a 2 week period, once a week.

Effect of Agar Composition on Germination

Status of Hypothesis

Agar composition did not significantly affect root growth in the Arabidopsis thaliana (Columbia).

Discussion

The 1.6% agar produced some of the longest roots, but statistical evidence showed no advantage among the different agar compositions.The fragile state of the 0.4% agar was another problem. The consistency of the 0.4% was so watery that it was difficult to measure root length because the plants were floating around in the dish.An unequal distribution of light over the plants also could have created skewed results. For the first week of the experiments, the agar dishes were laid out in such a way that the 0.4% and 1.6% dishes received more light than the 0.8% dishes. The problem was corrected for the second week, but the uneven light distribution could have provided an unfair advantage for the 0.4% and 1.6% dishes.While there was no significant advantage for any of the compositions, the statistical cutoff was almost crossed by the data. A larger sample size would be more appropriate given our hypothesis.

The authors are indebted to the tireless work of G. R. Davis and Ab Abercrombie; G. R. Davis for providing the resources and leadership necessary for this experiment and Ab Abercrombie for his assistance with the statistical analysis for the results.

Acknowledgements

Agar, a gelatinous substance derived from red algae, is commonly used at a concentration of 0.8% to grow Arabidopsis plants in the laboratory. To determine whether this is the optimal agar concentration for root growth, we tested in 0.8%, twice that at 1.6%, and half at 0.4%. The Arabidopsis thaliana ecotype Columbia was used for the experiment as it’s not from a region with extreme weather conditions.

Agar concentration had no effect on germination rate (p=0.262, Pearson Chi Squared Test df2=5.259.) data not shown

Effect of Agar Composition on Root Growth

Agar concentration had no statistical effect on root growth at 2 weeks (p= 0.062, Repeated measures analysis of variance, DF=2, 29 F= 3.06)

Different types of lights have been used to increase the growth of various plants. Our experiment tested whether LED or fluorescent lights produce plants with larger root length and higher germination rates. Fluorescent lights, which emit heat, some noise, and consume more energy, and use light that is not as concentrated as the light of the LED lights. LED lights use about 10% of the energy of fluorescent lights, are a more concentrated light source, and can last for a significant number of years more than the fluorescent lights.

Effects of LED and Fluorescent Lights on Growth of Arabidopsis Kevin O’Quinn, Mesha Arant, Jordan Ball, and T.J. White

Department of Biology, Wofford College, Spartanburg, SC 29303

Introduction

Materials and Methods

Results and Findings

Hypothesis

LED growing plates will allow the plants to grow quicker and larger. The percent germinated will be greater under the LED growing lights rather than underneath the florescent lights.

Materials•48 Arabidopsis seeds•Growing Plates•Fluorescent Growing Lights and LED Growing Plates•Agar•Pipettes•TapeMethods0.8% Agar was placed into 6 growing plates and were left to set. Three plates were designated for the LED lights, and three were designated for the fluorescent lights. 8 seeds were placed in each growing plate.The plates were sealed and placed in a vertical position under the LED and Fluorescent lights. The distance from the lights to the plants was 33.65cm. They were maintained with a photoperiod of 16 hours of light and 8 hours of darkness each day. Germination rates and root length were measured each week of the experiment.

Discussion

Status of Hypothesis

Plants that were grown under LED lights (n=24) had smaller root lengths than plants that were grown under fluorescent light (n=24). The germination rate, not shown, was not statistically relevant (Chi-square (dF=1)=0.137; p=.712). After looking at the growth rate from Week 1to Week 2, we found, using a variable-selection procedure and found that root length yielded the best results. Analyzing the variable using Fdf=1,36=11.8; p=.002. with this we concluded that the Fluorescent lights grew the roots of the Arabidopsis longer than the LED light panel.

LED growing plates did not produce plants with longer root lengths nor highergermination rates.

Root Length of Plants under Fluorescent and LED lights

Our experiment showed that fluorescent lights produced plants with longer roots than the LED light panel. The size of the roots that were grown by the Fluorescent lights had a considerable size advantage over the LED lights. Of course, one of the drawbacks of the Fluorescent lights is that they require a lot more energy to work than the LED’s. The LED’s use only about 10% of the energy of the Fluorescent. One of the things that might have affected the results was the height from the light source to the plants. Because the LED panel consisted of blue and red diodes, the chance that moving it either closer or farther from the plants may have optimized the productivity of the light panel. Either way, in this experiment, the Fluorescent lights grew the roots longer than the LED light panel. 

The chart shows the average growth of the roots of the two treatment groups. Along the x-axis is the treatment while on the y-axis is the length it grew. The circles show the average length while the error bars show 95% confidence intervals.

Explanation of Graph