Can-0 Zloc-1 The Effects of Drought on Stem Growth in Three Arabidopsis Ecotypes Hunter Soltis, Victor Makali, Allison Poole, and Lucy Monigle Wofford College, South Carolina NZ-1 Introduction Results Discussion Arabidopsis ecotypes have adapted to thrive in local environments with varying climates and precipitation. Three different ecotypes were selected based on the amount of precipitation they receive. During the first week, condition and ecotype had little effect on stem growth. During the second week condition and ecotype had individual effects on shoot growth. There was a significant difference in growth when both ecotype and condition were taken into account. 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 the soil was equally saturated for both drought and watering conditions. Therefore drought did not have a large effect on the different ecotypes which was expected. The second week was more interesting. Drought tolerance was visible among all three ecotypes, including those that are accustomed to high levels of precipitation. Arabidopsis shoot growth was not stunted by drought conditions. The seeds germinated under wet conditions grew to heights slightly lower than expected. 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 than two weeks. The longer the experiment, the more pronounced the differences will be. Drought plants should have been planted in a less water-saturated soil and watering conditions need to be regular throughout the week. Plants with irregular growth (bent or fallen stem) could have been measured using a more precise method. Effect of Drought on Stem Growth of 3 Arabidopsis Ecotypes at Two Weeks Adapted to different environments, one ecotype may be more susceptible to drought. The purpose of this study is to determine whether some ecotypes are more affected by drought than others. Can-0 is not expected to be affected by drought conditions while NZ-1 is expected to be greatly affected by drought conditions. Hypothesis Those ecotypes that grow in regions with high precipitation will be more adversely effected by drought and exhibit shorter shoot length. Methods At the end of week one, stem growth was not stunted or affected by drought conditions, in either ecotype, even for those that grow under high precipitation. Instead, there were subtle changes to the ecotypes despite varied conditions. The graph shows the results of week two, the noticeable affects on each ecotype in both wet and drought conditions. From each ecotype, 36 seeds were germinated in soil for 2-4 days under a photoperiod of 16hrs light/8hrs dark. Of those seeds, 18 from each ecotype were kept under wet conditions, watered every other day. The other 18 seeds of each ecotype were under simulated drought conditions and were not watered at all. All plants were kept 33.7 cm below fluorescent lights. Each tray was covered by a plastic lid. Plant shoots were measured once a week by a millimeter ruler. References www.wordtravels.com1 www.climate-charts.com2 www.brittanica.com3 ANOVA; Effect of Drought on Stem Growth of 3 Arabidopsis Ecotypes at Two Weeks Acknowledgements We would like to thank G.R. Davis, C. Abercrombie for their design and statistical analysis. The assistants T. Player and A. Steadman for their comments and technical assistance. Both the drought and non-drought conditions seemed to be growing at the same rate when measured at the end of the first week. By the end of the second week, there was a significant interaction between ecotype and condition (drought vs. non-drought). Obviously drought conditions affect different ecotypes in different ways. Error is due to the small sample size.