Plant phospholipases D: functions, structures, and enzymatic activities.

Phospholipases D (PLDs) (EC 3.1.4.4) are enzymes capable of hydrolyzing the distal phosphodiester bond of phospholipid (PL) substrates. PLD reaction frees phosphatidic acid (PA), a key intermediate in lipid metabolism and an important signaling molecule involved in multiple cellular and physiological processes. Widely distributed across prokaryotes and eukaryotes, PLDs have diversified considerably and fulfill distinct biological functions depending on the organism and physiological context. In plants, increasing evidence highlights their central roles in adaptation to abiotic and biotic stresses, reproductive processes, and developmental regulation, making them particularly relevant in the context of current agronomic and environmental challenges. This review examines the phylogenetic diversity of plant PLDs, with particular emphasis on cereal species, and summarizes recent advances in the characterization of their biological functions. Recent structural data obtained from plant PLDs also provide new insights into structure-function relationships within the PLD superfamily and help refine our understanding of the structural organization and enzymatic properties of plant PLDs.