Potassium loss is involved in tobacco cell death induced by palmitoleic acid and ceramide

Tobacco cell death induced by palmitoleic acid (16:1), ceramide, and KCN was found to possess features associated with program cell death (PCD), including cell volume decrease, loss of membrane integrity, DNA damage, nuclear and plastid disorganization, and chromatin condensation. Cell volume decrease was found to be caused by loss of intracellular K+. Ba2+ was able to prevent the K+ loss and it also protected the cells from death induced by 16:1 and ceramide but not KCN. The results suggest that K+ loss is a critical step in plant PCD. The inability of Ba2+ to prevent cell death was most likely due to its other effects of KCN, i.e., inhibition of cytochrome oxidase in the respiratory chain and generation of reactive oxygen species.