A plant vacuolar protease, VPE, mediates virus-induced hypersensitive cell death

Programmed cell death (PCD) in Animals depends on Caspase protease activity. Plants also exhibit PCD, for example as a response to pathogens, although a plant Caspase remains elusive. Here we show that vacuolar processing Enzyme (VPE) is a protease essential for a virus-induced hypersensitive response that involves PCD. VPE deficiency prevented virus-induced hypersensitive cell death in tobacco Plants. VPE is structurally unrelated to caspases, although VPE has a Caspase-1 activity. Thus, Plants have evolved a regulated cellular suicide strategy that, unlike PCD of Animals, is mediated by VPE and the cellular vacuole.