Green light reversal of blue-light-stimulated stomatal opening is found in a diversity of plant species

Reversal by green light of blue-light-stimulated stomatal opening was found across a number of plant species, including leguminous and nonleguminous dicots and grass and nongrass monocots. Simultaneous exposure to equal fluence rates of blue and green light resulted in ;50% reversal of normal blue light opening. Complete reversal occurred when the fluence rate of green light was approximately twice that of blue light. These results suggest that blue‐green reversibility of stomatal opening is a basic photobiological property of guard cells. The blue‐green reversibility of stomatal opening has been hypothesized to ensue from the cycling of two interconvertible, isomeric forms of the blue-light photoreceptor, zeaxanthin. Testing of blue‐green reversibility could provide a valuable diagnostic tool for zeaxanthin-mediated blue-light photoperception.