Aquaporin regulation in roots controls plant hydraulic conductance, stomatal conductance, and leaf water potential in Pinus radiata under water stress.

Stomatal regulation is crucial for forest species performance and survival on drought-prone sites. We investigated the regulation of root and shoot hydraulics in three Pinus radiata clones exposed to drought stress and its coordination with stomatal conductance (g_s ) and leaf water potential (Ψ_leaf ). All clones experienced a substantial decrease in root-specific root hydraulic conductance (K_root-r ) in response to the water stress, but leaf-specific shoot hydraulic conductance (K_shoot-l ) did not change in any of the clones. The reduction in K_root-r caused a decrease in leaf-specific whole-plant hydraulic conductance (K_plant-l ). Among clones, the larger the decrease in K_plant-l , the more stomata closed in response to drought. Rewatering resulted in a quick recovery of K_root-r and g_s . Our results demonstrated that the reduction in K_plant-l , attributed to a down regulation of aquaporin activity in roots, was linked to the isohydric stomatal behaviour, resulting in a nearly constant Ψ_leaf as water stress started. We concluded that higher K_plant-l is associated with water stress resistance by sustaining a less negative Ψ_leaf and delaying stomatal closure.

Duke Scholars

Author Jean Christophe Domec Environmental Natural Science