Observing Genetic Traits in Arabidopsis Thaliana Plants By Team Trichomes Kelly Hang Hardy Hang Daniel Mayer Belal Alammar

Background Discrete Traits – Traits that are either present or not present in the phenotype. There is never an intermediate. For example, the pea plant’s flower colors that Mendel first observed were either purple or white. Continuous Traits – Traits that have a range of phentotypes. There is an intermediate. For example, in snapdragons, the flower colors are red and white, and their intermediate, pink. Flowering time – The time it takes for a plant to produce flowers. Erecta phenotype – A discrete trait that allows the plant to stay erect on its own, without any outside contributor (such as rods). Anthocyanin – A purple pigment that leaves produce. It does not necessarily have to be visible. Trichomes – Three-prong hairs on the leaves of an Arabidopsis plant.

Purpose The purpose of the experiment is to observe trichome numbers, flowering times, the presence of the erecta phenotype, and the anthocyanin production in Arabidopsis thaliana plant.

Procedures Wet the pellets in the flats and unwrap the protective nets. Plant the seeds and label the pellets with their respective line number. The label was made using a long toothpick wrapped with tape. Wrap the flats with aluminum foil and place them in the refrigerator for 48 hours. After 48 hours, water them with 0.5 mL of Miracle-Gro and 500 mL of water and place them in the light box. The light box was two crates wrapped in aluminum foil with two light bulbs; one in each crate. Watch the plants every day for flowering time and record the observations.

(continued) Once the plants bloom, wrap the pellets with transparent sheets and label them with tape. When the plant produces the first true leaves, cut them off and count the number of trichomes using a hand lens or a dissecting microscope. Later, check the plant for the erecta phenotype. This is done by checking whether the plant will stay up without any support. To determine whether the line produces anthocyanin, cut off leaves that are near the bottom and place them with the petioles in the solution in vials filled with 0.5 mL sucrose assay. Place them in the light box for 48 hours. Check to see whether there is purple pigments on the leaves.

Results RIL Our Group Other Group Col 27.7 25.3 Ler 8.0 20 11.0 25 10.3 5.0 34 4.3 X 38 30.6 6.0 43 47 5.3 53 14.0 55 18.3 17.3 59 24.6 62 16.0

(continued) 65 7.0 6.3 66 6.6 2.0 69 7.3 12.0 70 X 8.6 72 8.0 75 12.3 77 14.3 78 17.6 82 11.0 85 10.0 89 14.0 90 13.0

(continued) 96 28.6 X 101 6.3 10.0 120 11.6 9.0 134 22.0 21.6 141 23.0 19.3 142 15.7 15.0 146 7.6 147 14.6 14.3 149 10.6 8.0 150 25.0 14.0 161 170 12.0 x

(continued) 177 22.6 18.0 178 22.3 31.6 182 X 183 12.3 7.3 201 26.0 15.0 206 10.3 12.0 226 20.6 19.0 229 24.0 14.0 249 16.3 17.3 280 9.3 16.0 336 4.3 382 402 11.6 17.0

(continued)

First Data Observed For Flowering (continued) First Data Observed For Flowering RILs 10/28/09 Col, Ler, 25, 28, 38, 47, 53, 55, 62, 69, 82, 83, 90, 102, 120, 121, 147, 149, 150, 170, 178, 201, 226, 249, 280, 336, 382 10/29/09 34, 59, 78, 138, 141, 142, 161, 177, 183, 229, 281, 402 11/2/09 65, 101, 170, 206, 224 11/3/09 20, 70, 96, 134 11/4/09 49, 59, 171 11/5/09 172 11/6/09 66, 77, 103, 175 11/9/09 – 11/16/09 None 11/17/09 146

RILs with Erecta Phenotype RILs that Produce Anthocyanin (continued) RILs with Erecta Phenotype 38 47 82 120 142 147 149 178 183 RILs that Produce Anthocyanin 89 90 101

Conclusions Flowering time and trichome numbers are continuous traits. Anthocyanin production and erecta phenotype are discrete traits. One possible source of error could be the fungi and algae that were growing in the pellets. These organisms may have absorbed nutrients from the soil, thus creating an unequal environment for each individual plant. This can deprive the plants of their nutrients may have caused the yellowing of the leaves, a condition called chlorosis. Another possible source of error could be that at one point, the plants were overwatered. The combination of both standing water and a constant supply of light may have contributed to more algae and fungi growth. There was also a time when the plants were under watered, and this probably inhibited plant growth. There was also a leak in the corner of one of the flats, which siphoned a significant amount of water into the tray below the flat, depriving the plants of water.