Look at the size of those pores! Variation in stomatal behavior in Brassica rapa suggests link to circadian clock

Abstract

The circadian clock is an endogenous c. 24 hour timekeeping mechanism which regulates a number of plant processes. Stomata are leaf pores which open and close for water and gas exchange. In this study, I sought to examine whether stomatal behavior is influenced by the clock. To do so, I measured the stomatal aperture of 8 lines of Brassica rapa (B. rapa) with different circadian periods (the time it takes the clock to complete one full oscillation) 1 hour before dawn and 1 hour after dawn over three days. I hypothesized that plants with different periods would differ in mean stomatal aperture at each time point and the amount that aperture changed between the two timepoints. I found that the lines differed in their aperture and change in aperture, though those with similar period length did not necessarily demonstrate similar trends in aperture.