Summary Phospholipase D ( PLD ) and its cleavage product phosphatidic acid ( PA ) are crucial in plant stress‐signalling. Although some targets of PLD and PA have been identified, the signalling pathway is still enigmatic. This study demonstrates that the phosphoprotein At5g39570, now called PLD ‐regulated protein1 ( PLD rp1), from Arabidopsis thaliana is directly regulated by PLD α1. The protein PLD rp1 can be divided into two regions with distinct properties. The conserved N‐terminal region specifically binds PA , while the repeat‐rich C‐terminal domain suggests interactions with RNA s. The expression of PLD rp1 depends on PLD α1 and the plant water status. Water stress triggers a pld α 1 ‐like phenotype in PLD rp1 mutants and induces the expression of PLD rp1 in pld α 1 mutants. The regulation of PLD rp1 by PLD α1 and environmental stressors contributes to the understanding of the complex PLD regulatory network and presents a new member of the PA ‐signalling chain in plants. Significance Statement This manuscript reports PLDrp1 protein as a target of PLD. This protein specifically binds to phosphatidic acid.