Sugar suppression of aquaporin expression and leaf hydraulics ($)

Sugar is a signal as well as an energy source, and plants monitor sugar levels to maintain an appropriate growth rate and rate of photosynthesis. A new study by Kelly et al. points to a role for sugars in the expression and activity of plasma-membrane (PIP) aquaporins. Aquaporins (AQP) are membrane channels for water and carbon dioxide, and their regulated activity contributes to hydraulic conductivity. The authors examined the responses of wildtype and mutant or overexpression lines of Arabidopsis to sugar treatments. They found that elevated sugar levels (or hexokinase expression) decreased the expression of PIP AQPs and leaf conductance, and speculate that sugar signals the plant to decrease its transpiration rate (which is determined in part by the need for CO2 uptake for photosynthesis and sugar production). Plant J. 10.1111/tpj.13568