By Rebecca Kim and Jeff Kimmel
This first week was all about careful preparation. In order to prepare for successful planting the following week, the first step of our experiment was to sow the Arabidopsis seeds to wet filter paper and have it undergo cold treatment for 1 week. Cold treatment is an important step of our experiment because it helps to improve the rate and synchrony of germination. Cold treatment ensures that all of our seeds will germinate at the same time, which is vital to our experiment. In addition to undergoing cold treatment, this first week of sowing seeds onto filter paper helped to alleviate the daunting task of planting almost 4000 seeds the following week. This task required keen eyesight, steady hands, and a lot of patience.
To begin, we divided our class into groups. Each group was in charge of a different genotype. Each group was given the same set of tools necessary for success: filter paper, paintbrushes, petri dishes, wash bottles, water, ethanol, markers, and of course lots of tiny Arabidopsis seeds! After acquiring the necessary materials, the next step was to label all of the petri dishes we needed with our assigned genotype. Then we cut each filter paper into 6 equal wedges, being careful not to cut all the way to the center (this way the filter papers could remain intact during cold treatment. Then when it comes time to planting, each wedge containing a seed can easily be separated when wet, and placed in the correct pot). After the filter paper was cut, each wedge was labeled with our assigned genotype (A-F, P1-P5). Then, we lay the filter paper in a petri dish and wet the paper with just enough water so that the paper would stick to the dish without an excess amount of water in the dish. This process also helped with keeping the Arabidopsis seeds in place.
Now we were ready to start placing the seeds on the filter paper! Each group had 2 beakers, 1 filled with water and 1 filled with ethanol. First we dipped our paintbrushes in ethanol to sterilize the brush, then in water. Using our wet paintbrushes we carefully brushed one seed onto each filter paper wedge. This was where the keen eyesight and lots of patience came into play… The seeds were VERY small! In between every few seeds, we dipped our paintbrushes in ethanol and then again in water, just to be safe. Finally, we covered the petri dishes containing 6 seeds each in saran wrap. This helped to prevent the filter paper from drying out during cold treatment. Finally, the petri dishes were placed in a cold incubator between 3-5°C for 1 week. After 1 week in the incubator, the seeds will be ready for planting!