Analysis of Arabidopsis thailiana Traits Hairy Potters – (Nina Abon, Kyle Bauer, Brittni Naylor, Ali Thomason, Jared DeSoto)

Abstract Arabidopsis thaliana is a small flowering plant that is extensively used as a model organism in plant biology. Arabidopsis is a member of the Brassicaceae family, which includes cultivated species such as cabbage. In this study, four traits were observed: trichome number, flowering time, Erecta phenotype, and anthocyanin pigmentation. The trichome number and flowering time were found to be continuous, while the Erecta phenotype and anthocyanin pigmentation were found to be discrete traits.

Introduction The traits observed by Gregor Mendel in his pea plants were all discrete traits that are usually controlled by only one gene. However, not all traits are as simple as these. Most traits are controlled by multiple genes and therefore have a wide range of phenotypic variation. Some phenotypic traits are not controlled by inheritance at all, but instead are attributed to the environment. Not only does the information stored in plant DNA control their traits, but forces like water availability, sunlight availability, and nutrient absorption can also affect a plant’s traits. Arabidopsis are good model plant species because of their small height and short life span. It does not take long for seeds to mature, which makes it easy to study traits of the plant.

Hypothesis We hypothesize that the trichome number, Erecta phenotype, and flowering time are all continuous traits on Arabidopsis plants. However, we also hypothesize that the Anthocyanin production is a discrete trait on Arabidopsis.

Experimental Methods Five Arabidopsis seeds were placed into each soil pellet. The seeds were watered and placed in the refrigerator for 48 hours. After 48 hours, the pellets were placed into light boxes (where they remained for the duration of the experiment). The plants were watered with .5 mL of Miracle Grow in a 500 mL solution as needed. Periodically the lines which have open flowers and buds were observed and recorded in a journal.

Experimental Method: Trichome Data Three leaves (the first true leaves) from each line were taken and observed under a dissecting scope and hand lenses. The number of trichomes on each leaf were counted. The numbers for each line were averaged for our group and then the data from both groups was compared.

Experimental Method: Anthocyanin Assay In a centrifuge tube, three leaves were inserted into 1 mL of a 10% sucrose solution. These leaves were obtained from the same line but from two different plants. After placing the leaves in the tube with the solution, the tubes were placed into a light box for 48 hours.

Experimental Methods: Erecta Phenotype The Erecta Phenotype was measured by removing the plastic tube and observing the plant to see if it could stand erect on its own.

Experimental Method: First Flowering The plants were observed each day and the lines with open flowers and buds were recorded. The criteria for open flowers were that the inside of the flower had to be visible.

Data: Trichome

Data: Open Flowers First Flowering Days 27-Oct 29-Oct 3-Nov 4-Nov 25 249 72 No new lines 70 65 53 38 201 75 66 47 226 134 ler 55 20 77 146 62 183 89 83 90 12 85 206 147 69 161 149 45 170 82 178 43 280 101 281 120 336 382 402 Col

Data: Erecta Phenotype The lines that showed the Erecta phenotype were: 280 47 147 206 142 170 43 149 178 83

Results: Anthocyanin Test The Anthocyanin test failed. No purple pigment was observed in the leaves.

Results: Trichome The results showed that trichome number for Arabidopsis is continuous because the data showed no discernable trend. Sources of Error: On some lines, it was difficult to find the first true leaf as well as counting the trichomes. It was also hard to find the first true leaf because some lines were dying.

Results: Erecta Phenotype Only short to medium height plants seemed to display the Erecta phenotype. The lines with thicker stems demonstrated the phenotype. The taller lines did not show the Erecta phenotype at all.

Results: Open Flowers The flowers matured earlier than expected. Possible causes for this are fungus, mold, and an unstable environment. A few lines never germinated for unknown reasons.

Pictures Smaller plant with broader leaves. Plants continued to grow.

Pictures (cont.) Seed pods are shown. Taller phenotype.

Conclusion Our experiment proved our hypothesis partially correct. We were wrong in hypothesizing that the Erecta phenotype is a continuous trait when it is in fact discrete.

Acknowledgements We would like to thank the following people: Dr. Allison Landry Lisa Kanizay Group Trichomes