Are TIPs involved in the stomatal regulation in sunflower under different conditions?

Abstract

In this study we aimed at elaborating the contribution of sunflower stomata on both sides in the stomatal conductance (gs) and the relation between its regulation and specific aquaporins expression under different conditions. Our results indicated higher stomatal index of the adaxial than the abaxial as well as the photosynthesis (A), manifesting that stomatal index was a key factor for A and/or stomatal conductance (gs). Sunflower plants could absorb CO2 from both leaf surfaces and therefore have a more efficient photosynthetic CO2 uptake and fixation rates than other C3 species maintaining the high concentration of intercellular CO2. We also indicated that stomatal regulation rather than stomata per se determines the rate of transpiration (E). Key regulators of stomata are plant vacuoles in which aquaporins (TIPS) function. Insilico characterization of sunflower TIPS deduced from database indicated a conserved motif MIP with other species proved to transport water and involved in many different physiological processes. Inconsistent regulation of TIPs under different conditions was detected indicating TIPs were not involved in stomatal regulation at these conditions. Hierarchical analysis showed that TIP7 was distantly related to the other sunflower identified aquaporins.