Plant cells show an acquired insensitivity to Brefeldin A

The parameters of Brefeldin A (BFA) action in plant cells have been further investigated in maize root tips. Incubation of maize root tip cells with 100 g ml^-1 BFA for 2 h induces the vesiculation and aggregation of Golgi membrane to form BFA compartments; an effect that is reversed by incubation of the cells in BFA-free medium. In this paper, the effects of prolonged incubation with BFA are reported, revealing that Golgi stacks spontaneously re-form in the presence of this drug after incubation for 12 h or 24 h. The observation that the same BFA solution is still able to induce the formation of BFA compartments in fresh roots suggests that this recovery is not due to metabolism, detoxification or depletion of the drug. Furthermore, incubation of maize roots with a fresh 100 g ml^-1 BFA solution for 2 h following 24 h BFA treatment fails to induce the reformation of BFA compartments. Thus, an acquired insensitivity to BFA in plant cells, that has not been observed in mammalian cells to date, is indicated.