Arabidopsis PLD zeta 1 and PLD zeta 2 localize to post-Golgi membrane compartments in a partially overlapping manner

Key message Arabidopsis PLD zeta 1 and PLD zeta 2 localize to the trans-Golgi network and to compartments including the trans-Golgi network, multi-vesicular bodies, and the tonoplast, respectively, depending on their N-terminal regions containing PX-PH domains. Phospholipase D (PLD) is involved in dynamic cellular processes, including membrane trafficking, cytoskeletal reorganization, and signal transduction for gene expression, through the production of phosphatidic acid in membrane compartments specific to each process. Although PLD plays crucial roles in various plant phenomena, the underlying processes involving PLD for each phenomenon remain largely elusive, partly because the subcellular localization of PLD remains obscure. In this study, we performed comparative subcellular localization analyses of the Arabidopsis thaliana PX-PH-PLDs PLD zeta 1 and PLD zeta 2. In mature lateral root cap cells, own promoter-driven fluorescence protein fusions of PLD zeta 1 localized to the entire trans-Golgi network (TGN) while that of PLD zeta 2 localized to punctate structures including part of the TGN and multi-vesicular bodies as well as the tonoplast. These localization patterns were reproduced using N-terminal partial proteins, which contain PX-PH domains. An inducibly overexpressed fluorescence protein fusion of the PLD zeta 2 partial protein first localized to punctate structures, and then accumulated predominantly on the tonoplast. Further domain dissection analysis revealed that the N-terminal moiety preceding the PX-PH domain of PLD zeta 2 was required for the tonoplast-predominant accumulation. These findings suggest that PLD zeta 1 and PLD zeta 2 play partially overlapping but nonetheless distinctive roles in post-Golgi compartments along the membrane trafficking pathway from the TGN to the tonoplast.