Reversal by green light of blue light-stimulated stomatal opening in intact, attached leaves of Arabidopsis operates only in the potassium-dependent, morning phase of movement.

Green light reversal of blue light-stimulated stomatal opening was discovered in isolated stomata. The present study shows that the response also occurs in stomata from intact leaves. Arabidopsis thaliana plants were grown in a growth chamber under blue, red and green light.

The blue light-specific response of Vicia faba stomata acclimates to growth environment.

Stomata in epidermal strips from growth chamber-grown Vicia faba leaves opened less in response to white light than did stomata from greenhouse-grown leaves. Chlorophyll-mediated, red light-stimulated opening was similar in stomata from the two growth conditions, but stomata from the growth chamber environment had a severely reduced response to blue light. Transfer of plants between the two growth conditions resulted in an acclimation of the stomatal blue light response.

Blue light and phytochrome-mediated stomatal opening in the npq1 and phot1 phot2 mutants of Arabidopsis.

Recent studies have shown that blue light-specific stomatal opening is reversed by green light and that far-red light can be used to probe phytochrome-dependent stomatal movements. Here, blue-green reversibility and far-red light were used to probe the stomatal responses of the npq1 mutant and the phot1 phot2 double mutant of Arabidopsis. In plants grown at 50 micromol m-2 s-1, red light (photosynthetic)-mediated opening in isolated stomata from wild type (WT) and both mutants saturated at 100 micromol m-2 s-1.

Relative humidity is a key factor in the acclimation of the stomatal response to CO(2).

Previous work has shown that stomata of growth chamber-grown Vicia faba leaves have an enhanced CO2 response when compared with stomata of greenhouse-grown plants. This guard cell response to CO2 acclimatizes to the environmental conditions on the transfer of plants between the two environments. In the present study, air relative humidity is identified as a key environmental factor mediating the changes in stomatal sensitivity to CO2.

Phytochrome and blue light-mediated stomatal opening in the orchid, paphiopedilum.

Guard cells of the orchid genus, Paphiopedilum have been reported to lack developed chloroplasts and detectable chlorophyll a autofluorescence. Paphiopedilum stomata lack a photosynthesis-dependent opening response but have a blue light-specific opening. The present study found that low fluence rate green and red light elicited stomatal opening in Paphiopedilum and this opening was reversed by far red light, indicating the presence of a phytochrome-mediated opening response.

The guard cell chloroplast: a perspective for the twenty-first century.

The guard cell chloroplast is the site of perception of blue light and of photosynthetically active radiation, and of at least one of the mechanisms sensing CO in the guard cell. The guard cell chloroplast has been the focus of intense controversy over its capacity for light sensing and photosynthetic carbon fixation, and the osmoregulatory mechanisms mediating stomatal movements. It is argued here that a primary reason behind these long-lived controversies is the remarkable plasticity of the guard cell, which has resulted in responses being generalized as basic properties when opposite responses appear to be the norm under different environmental or experimental conditions.

The CO(2) response of Vicia guard cells acclimates to growth environment.

Stomata of growth chamber-grown Vicia faba leaves have an enhanced CO(2) response, measured as change in stomatal aperture, compared to stomata of greenhouse-grown leaves. Reciprocal transfer experiments showed that the stomatal response to CO(2) acclimated to the growing environment. Stomata of growth chamber-grown leaves transferred to a greenhouse lost their high CO(2) sensitivity within 2-3 d while stomata of greenhouse-grown leaves transferred to a growth chamber acquired a high CO(2) sensitivity within 5-7 d.

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.