Abstract
Leaf epidermal peels of Arabidopsis (Arabidopsis thaliana) mutants lacking either phototropins 1 and 2 (phot1 and phot2) or cryptochromes 1 and 2 (cry1 and cry2) exposed to a background of red light show severely impaired stomatal opening responses to blue light. Since phot and cry are UV-A/blue light photoreceptors, they may be involved in the perception of the blue light-specific signal that induces the aperture of the stomatal pores. In leaf epidermal peels, the blue light-specific effect saturates at low irradiances; therefore, it is considered to operate mainly under the low irradiance of dawn, dusk, or deep canopies. Conversely, we show that both phot1 phot2 and cry1 cry2 have reduced stomatal conductance, transpiration, and photosynthesis, particularly under the high irradiance of full sunlight at midday. These mutants show compromised responses of stomatal conductance to irradiance. However, the effects of phot and cry on photosynthesis were largely nonstomatic. While the stomatal conductance phenotype of phot1 phot2 was blue light specific, cry1 cry2 showed reduced stomatal conductance not only in response to blue light, but also in response to red light. The levels of abscisic acid were elevated in cry1 cry2. We conclude that considering their effects at high irradiances cry and phot are critical for the control of transpiration and photosynthesis rates in the field. The effects of cry on stomatal conductance are largely indirect and involve the control of abscisic acid levels.
Highlights
Leaf epidermal peels of Arabidopsis (Arabidopsis thaliana) mutants lacking either phototropins 1 and 2 or cryptochromes 1 and 2 exposed to a background of red light show severely impaired stomatal opening responses to blue light
The aim of this article was to characterize the light response of stomatal conductance in intact leaves of the phot1 phot2 and cry1 cry2 double mutants to elucidate (1) whether cry is a photoreceptor involved in the blue light system that controls stomatal conductance of intact leaves, and (2), the contribution of phot and cry to the diurnal dynamics of stomatal conductance, transpiration, and photosynthesis in plants grown under full natural radiation
Arabidopsis wild-type and the double mutants cry1 cry2 and phot1 phot2 plants were grown under natural radiation in a glasshouse or outdoors for 6 or 5 weeks, respectively
Summary
Leaf epidermal peels of Arabidopsis (Arabidopsis thaliana) mutants lacking either phototropins 1 and 2 (phot and phot2) or cryptochromes 1 and 2 (cry and cry2) exposed to a background of red light show severely impaired stomatal opening responses to blue light. The blue light-dependent system would be important for stomata opening under low irradiances, such as the understory of dense canopies, where light levels might not exceed the threshold for the red-light response (Zeiger and Field, 1982) This idea is consistent with the promotion of plant growth capacity and photosynthetic rates by phot in low light environments (Takemiya et al, 2005). Based on these arguments, one would expect blue light photoreceptors to affect stomatal conductance of fully exposed, nonshaded plants, only at both extremes of the photoperiod.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
