Abstract— The responses of stomata from Paphiopedilum harrisianum, Orchidaceae, to light and CO2 were studied in epidermal peels. Stomatal opening under red light was indistinguishable from that in darkness, whereas blue light promoted opening above dark levels. The ineffectiveness of red light in causing stomatal opening was confirmed in the presence of 100 μM KCN; average apertures in both darkness and red light were 53% of those measured in the absence of the inhibitor, whereas under blue irradiation, the KCN inhibition was only 30%, with average apertures two‐fold of those measured under red light or darkness. Fluence rate response curves under blue light were typical of a single photoreceptor; removal of CO2 increased aperture values without a significant light‐CO2 interaction. The lack of a stomatal red light response contrasts with results obtained in species with chlorophyllous stomata in which red light consistently causes stomatal opening, and suggests that the previously reported red light responses in stomata from intact Paphiopedilum leaves resulted from indirect effects, such as depletion of intercellular CO2 by mesophyll photosynthesis. In isolation, Paphiopedilum stomata appear to rely on a blue light photosystem for their responses to light and fail to open under red light because of their lack of guard cell chloroplasts.
|Original language||English (US)|
|Number of pages||4|
|Journal||Photochemistry and Photobiology|
|State||Published - Nov 1983|
All Science Journal Classification (ASJC) codes
- Physical and Theoretical Chemistry