Abstract
Green light is a major constituent of sunlight and is enriched in the leaf canopy. Compared with the stomatal responses to red light or blue light, virtually nothing is known for the stomatal responses to green light. Using intact sunflower leaves, we demonstrated that green light induces stomatal opening and suggested the existence of a green light receptor (Wang et al., 2008, PCE 31: 1307; PCP in press). This time, we present our recent data of the stomatal response to green light.
Stomatal opening in response to green light seems to be a phenomenon common to several herbaceous species, including sunflower, tobacco, and Arabidopsis thaliana. When the photosynthetic rate and stomatal conductance (Gs) of these leaves attained their steady states by a saturating red light, a weak green light pulse induced a further increase in Gs. It suggests that green light may employ a photosynthesis-independent pathway to induce stomatal opening. Moreover, a cyptochrome double mutant of A. thaliana showed significantly smaller green light response than the wild type. From these, we propose that cryptochromes to be a most likely candidate for green light receptor to mediate stomatal opening.
