Regulation of plant water loss by manipulating the expression of phospholipase Dα

Phospholipase D (PLD) has been implicated in various processes, including signal transduction, membrane trafficking, and membrane degradation. Multiple forms of PLD with distinct biochemical properties have been described in the cell. In Arabidopsis, PLD alpha and PLD gamma but not PLD beta, were detected in guard cells, and antisense suppression resulted in a specific loss of PLD alpha. The abrogation of PLD alpha rendered plants less sensitive to abscisic acid and impaired stomatal closure induced by water deficits. PLD alpha -depleted plants exhibited accelerated transpirational water loss and a decreased ability to tolerate drought stress. Overexpression of PLD alpha enhanced the leaf's sensitivity to abscisic acid. These findings provide molecular and physiological evidence that PLD alpha plays a crucial role in regulating stomatal movement and plant-water status.