| Water movement across cell membranes is largely facilitated by aquaporins (water channel proteins). The present study investigated mechanisms of root water flow regulation through phosphorylation/dephosphorylation processes and protein synthesis. Roots of solution culture-grown aspen (Populus tremuloides Michx.) seedlings were treated with different chemical inhibitors of the above processes and the steady-state root water flow, root respiration, acid phosphatase activity, stomatal conductance, root hydraulic conductivity and apoplastic water flow were examined. Most of the phosphorylation/dephosphorylation inhibitors reduced the root water uptake and the activity of acid phosphatases while they had no effect on root respiration. The protein synthesis inhibitor rapidly inhibited root water flux and aquaporin expression suggesting that transcriptional and (or) translational regulation of aquaporin synthesis could play a significant role in regulating root water uptake. The phosphorylation/dephosphorylation events and protein synthesis appear to be among the primary processes regulating root water uptake. |
