Light and gravity have profound and interacting effects on plant growth and the goal of this study was to determine the effects of these stimuli on the large internodal cells of the aquatic plant Chara. This represents the first report of the interactions of light and gravity in single plant cells. Time-lapse video was used to observe phototropic and gravitropic curvature of Chara. Plants in blue light (2.4 μE) showed the greatest response whereas red light at 0.10 μE elicited no photropic response. This light source was subsequently used to observe the gravity response without the complicating factor of the light response. The gravity response was slower than the light response and was observed over a longer period than the light experiments. In future experiments we will determine the additive and antagonistic effects of light and gravity in these cells. RNA was isolated from single cells as a first step toward determining which genes are expressed in the light and gravity responses.
Faculty Mentor: Mark Staves, Cell and Molecular Biology