Quantifying the Effects of Light on Tank Bromeliads
Mentor:Gretchen North, Professor of Biology, Occidental College
Tank bromeliads are tropical epiphytes that grow in tree canopies. As a result they lack both soil and roots for conducting water. Therefore the majority of water uptake occurs through aquaporins within the leaves that form their tank. Aquaporins are channel proteins that play an essential role in water conductivity, and protons have been shown to inhibit aquaporins. Field observations indicate a correlation between low pH of the tank water and light exposure (G. B. North, unpublished observations). The purpose of this research was to empirically confirm this correlation with the intent to examine aquaporin expression of the samples. To address this question eight Aechmea nudicaulis, a species of tank bromeliad found in high light canopy environments, were grown in a controlled growth chamber, four in high light conditions and four in low light conditions. Their pH was recorded daily for a period of four weeks. Samples were collected from the plants and stored for future RNA extraction. The difference in pH between the groups was found to be highly significant, with the high light treatment having a lower pH. For future experiments, a method for manipulating pH without killing the plant was needed. An additional set of Aechmea nudicaulis v. cuspidata was used to test natural alternatives to harsher acids. Samples of naturally acidic leaves were collected on Occidental campus, and were used to make “slurries.” Cercis occidentalis, with a pH of approximately 4.20 was found to have the lowest pH. In addition to preparing the plants and methods, optimization was necessary to prepare for Quantitative PCR. Total RNA of Aechmea nudicaulis was isolated and was used in optimizing a DNase treatment.