Fructose Regulation of Stomatal Movement and its Effects on the Photosynthetic System in Vicia faba L.

Background: Vicia faba L. is a significant grain legume that is rich in protein and nutrients. It is widely cultivated for human consumption and animal feed in temperate regions. As a signaling molecule, fructose is involved in many metabolic and developmental processes. The objective of this study was to demonstrate whether fructose may increase reactive oxygen species (ROS) production in guard cells inducing stomatal closure and examine whether the exogenous application of fructose may regulate photosynthesis and chlorophyll fluorescence characteristics. Methods: After approximately 4 weeks of sowing the treated broad bean seeds, the fully inflated leaves were used for experimental data collection including stomatal movement, gas exchange, chlorophyll fluorescence and ROS production in guard cells. Result: Fructose reduced stomatal conductance (Gs), transpiration rate (Tr) and stomatal aperture of intact leaves, indicating that fructose can trigger stomatal closure in a dose- and time-dependent manner in the epidermal peels of the broad bean plant (Vicia faba L.). Meanwhile, fructose increased the photochemical efficiency, photosynthetic rate (Pn) and water use efficiency (WUE). Fructose-induced stomatal closure was associated with nitric oxide (NO), calcium ion (Ca2+), aquaporin and ROS.