Water deficit triggers phospholipase D activity in the resurrection plant Craterostigma plantagineum

Phospholipids play an important role in many signaling pathways in animal c ells. Signaling cascades are triggered by the activation of phospholipid cl eaving enzymes such as phospholipases C, D (PLD), and A(2). Their activitie s result in the formation of second messengers and amplification of the ini tial signal. In this study, we provide experimental evidence that PLD is in volved in the early events of dehydration in the resurrection plant Cratero stigma plantagineum. The enzymatic activity of the PLD protein was activate d within minutes after the onset of dehydration, and although it was not in ducible by abscisic acid, PLD activity did increase in response to mastopar an, which suggests a role for heterotrimeric G proteins in PLD regulation. Two cDNA clones encoding PLDs, CpPLD-1 and CpPLD-2, were isolated. The CpPL D-1 transcript was constitutively expressed, whereas CpPLD-2 was induced by dehydration and abscisic acid. Immunological studies revealed changes in t he subcellular localization of the PLD protein in response to dehydration. Taken together, the data on enzymatic activity as well as transcript and pr otein distributions allowed us to propose a role for PLD in the events lead ing to desiccation tolerance in C. plantagineum.