Now in my second year at the Tooker Lab, I have come to realize that I will almost certainly never be able to go more than a day or two at the lab without having to ask someone where I can find the aluminum foil, or the extra sample tubes, or any of the other miscellaneous lab objects that never seem to be where they are supposed to be. Nevertheless, I am shocked to find that other lab members are now asking me questions about processing phytohormone tissue and running samples on the GC-MS. While last summer I sometimes felt like I was just blindly following directions, now I feel comfortable making suggestions for procedural decisions and new research paths.
Anjel and I have had a couple of main focuses for our research over the past several months. We are still trying to determine what kind of differences exist in induced defense responses between the goldenrod candy-caned and straight stem genotypes. We first tried to address this question last summer by measuring the induced phytohormone levels for the two genotypes. There was a trend in our data showing that the induced defense responses for candy-caned goldenrod were lower than those for straight-stemmed goldenrod. Unfortunately, the p-value was not low enough for us to say with confidence that we were observing a truly significant difference. So, as seems to be the case for most scientific work, we had to repeat the experiment.
This spring, Anjel and I restarted with the same basic premise and goal, but tweaked our procedure slightly in hopes of better results. Mainly, we moved the plants into the greenhouse to limit variation in conditions such as weather and herbivore damage. Also, instead of just picking plants from different areas of a field like last summer, we grew these plants from rhizomes so that all of the plants in each group would be genetically identical. Despite our best efforts, problems still emerged. The plants with straight stems were growing much quicker than the ones with candy-caned stems, and we quickly realized we would not be able to run the experiment because the groups would not be ready at the same time. So, like any scientists who are experienced with unexpected developments, we improvised.
First, we planted some new straight plants hoping that they would be the right size to use with the first group of candy-caned plants that were still fairly small. Right now, those plants are getting close to being ready for our experiment, and we should be able to start taking tissue samples in a few weeks. However, there were still a bunch of straight goldenrod plants that were just going to go to waste if we didn’t find some way to use them. We decided to see if we could induce stem bending in these genotypically straight plants to mimic the candy-caned stems. We made several pastes by using lanolin as our base and adding different amounts indole-3-acetic acid (IAA), which is a common plant auxin that stimulates cell elongation. We applied the pastes to one side of the plant stems, hoping that those cells would lengthen and cause the stem to bend. For once, everything went smoothly and the higher concentrations of IAA caused the stems to bend noticeably. After a few applications of the paste, we took tissue samples from the bent stem, the bud, and the leaves and processed them for phytohormone analysis.
They are still waiting to be run on the GC-MS, but once they are finished we should be able to determine how the applied IAA spread throughout the plant or whether or not it spread at all. Overall, despite our experiments not going exactly as planned, we have been able to collect lots of tissue samples that should help us reach a better understanding of goldenrod stem characteristics and their defensive responses.