In my lab, we study a variety of plant responses to environmental signals – things like light, gravity, and touch, to name a few. We study these signaling processes with several overlapping techniques. One of the primary tools we use is image analysis to determine how, when, and where roots respond to environmental cues. By connecting cameras to computers and capturing images every 30 seconds or so, we can get a very high-resolution picture of plant growth responses. Going one step further, we’ve interfaced our image capture and analysis software to a feedback system that lets us constrain any region of the growing root to any angle we choose. This gives us the ability to measure growth responses in a new way, one that is beginning to reveal new insights into the regulation of growth.
Another tool we use routinely in my lab is mutant analysis. Over the last 20 years, the use of a plant model system called Arabidopsis thaliana has produced a library of mutations in each gene of the plant. A mutation in any gene can be ordered online like a pizza now, and we can test whether that particular gene is involved in growth regulation by looking for differences in the mutant compared with the wild-type using our high-res image analysis system.
A third approach we use is the visualization of gene expression changes, as indicated by the figure to the left. By fusing a fluorescent protein with a particular promoter element, we can visualize the activation of that particular promoter using a fluorescent microscope. In our case, we’ve been using a synthetic promoter that is up-regulated in response to the plant hormone auxin. Therefore, we see the fluorescent protein expressed in cells in which auxin has reached high concentrations. In this experiment, the root was gravistimulated for 3 h such that the right side in this image was on the lower flank. You can read more about such an experiment in this paper on auxin transport during gravitropism and in our recent paper on auxin transport and gravitropism in a starchless mutant.
- Meka George
- Troy Jones
- Rachael Quick
- Allyson Wojnoski
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