November 30, 2011
Arabidopsis: What Turns Seeds On
An Interaction between At5Ptase1 and ABA
An experiment was conducted to see how At5Ptase1 and ABA interacted. The At5Ptase1 gene has the ability to alter signal transduction. Abscisic acid (or ABA) is a principal drought-sensing hormone in plants. Compared to wild-type plants, some mutants showed delayed germination with the application of ABA (Burnette). The experiment was performed to see if Burnette had a point, and data was collected. The data seemed to match well with the hypothesis that states, “If a diluted amount of abscisic acid is applied to a Petri dish containing Arabidopsis thaliana seeds, then those seeds will exhibit delayed germination. More specifically, the mutant A. thaliana seeds will manifest a slower germination than the wild-type seeds.”
We were given a mutant type of Arabidopsis Thaliana called At5Ptase1. We went to the website recommended in determining how to best conduct the experiment. We noticed that Abscisic acid helped to prevent seeds from growing. Upon further investigation from “A Physiological, Biochemical and Structural Analysis of Inositol Polyphosphate 5-Phosphatases from Arabidopsis thaliana and Humans,” we concluded that we should Abscisic acid to see what would happen. We got the title of our experiment from www.woodrow.org, where we also found out how to make Abscisic acid. Based on the information found from “Molecular Biology of the Cell,” we hypothesized that if a diluted amount of abscisic acid is applied to a Petri dish containing Arabidopsis thaliana seeds, then those seeds will exhibit delayed germination. More specifically, the mutant A. thaliana seeds will manifest a slower germination than the wild-type seeds.
In order to do the experiment, we needed to create Abscisic acid (also known as ABA). We took 0.002 grams of ABA powder and mixed it with 0.02 mL of 95% ethanol and 10 mL of distilled water in a test tube with a screw top. Afterwards, we took two Petri dishes and divided them in half—on one side it was labeled mutant type and on the other was labeled wild type. The control Petri dish had the respective A. thaliana seeds on each side. The experiment Petri dish had the ABA solution spread around first and then the seeds placed on the respective sides. Both Petri dishes were under the same amount of light. After one week, we counted the number of root tips, the number of plants that germinated, and measured the lengths of randomly sampled stems by using ImageJ.
We used eighteen random samples of each seed to determine length. Figure 1 shows the Petri dish with ABA where the mutant seeds grew more than the wild type seeds. Figure 2 shows the Petri dish without ABA where the wild type seeds grew more than the mutant seeds. Figures 3 and 4 show the lengths of each of the seeds.
Upon completion of our experiment, we discussed possible underlying factors that could have affected and/or contributed our experiment. We used a Petri dish without ABA solution to act as a control.