Light, power, action! Interaction of respiratory energy and blue light induced stomatal movements.

Although the signalling pathway of blue light dependent stomatal opening is well characterized, little is known about the interspecific diversity, the role it plays in the regulation of gas exchange and the source of energy used to drive the commonly observed increase in pore aperture. Using a combination of red and blue light under ambient and low [O2 ] (to inhibit respiration), the interaction between blue light, photosynthesis and respiration in determining stomatal conductance was investigated. These findings were used to develop a novel model to predict the feedback between photosynthesis and stomatal conductance under these conditions. Here we demonstrate that blue light induced stomatal responses are far from universal, and that significant species-specific differences exist both in term of rapidity and magnitude. Increased stomatal conductance under blue light reduced photosynthetic limitation, at the expense of water loss. Moreover, we stress the importance of the synergistic effect of blue light and respiration in driving rapid stomatal movements especially when photosynthesis is limited. These observations will help re-shape our understanding of diurnal gas exchange in order to exploit the dynamic coordination between A and gs , as a target for enhancing crop performance and water use efficiency. This article is protected by copyright. All rights reserved.