Role of Root Hydraulics in Plant Drought Tolerance

Frequent and intense drought episodes impact agricultural productivity by challenging plant water status. The maintenance of hydraulic conductivity plays a key role in deciphering stress-induced impacts. Understanding drought-induced changes to root anatomical traits is important to improve plant drought adaptation. However, little is known about the root hydraulic strategy and xylem transport phenomena at the cellular and structural levels. Moreover, root architectural adaptations that systematically govern hydraulic safety as a function of water availability are largely unknown. A comprehensive understanding of root hydraulics and root architecture is needed to identify strategies to improve water uptake and modulate crucial root traits for crop improvement, especially in drought-prone areas. This review highlights the function of roots and the root–shoot junction as a hydraulic safety valve to quickly transport water in the radial and axial direction at cellular and tissue levels under drought stress.