Increased expression of phospholipase D1 in guard cells decreases water loss with improved seed production under drought in Brassica napus

The activation of phospholipase D1 (PLD1) produces lipid messenger phosphatidic acid and promotes stomatal closure in Arabidopsis. To explore the use of the PLD1-mediated signalling towards decreasing water loss in crop plants, we introduced Arabidopsis PLD1 under the control of a guard cellspecific promoter AtKatIpro into two canola (Brassica napus) cultivars. Multiple AtKatIpro::PLD1 lines in each cultivar displayed decreased water loss and improved biomass accumulation under hyperosmotic stress conditions, including drought and high salinity. Moreover, AtKatIpro::PLD1 plants produced more seeds than did WT plants in fields under drought. The results indicate that the guard cellspecific expression of PLD1 has the potential to improve crop yield by enhancing drought tolerance.