Tunicamycin and Brefeldin A induce in plant cells a programmed cell death showing apoptotic features

The recent identification of DAD (defender against apoptotic death) gene in plants suggests that the N-linked glycosylation of proteins could be an im portant control point of plans programmed cell death. In this paper we desc ribe the effects of Tunicamycin. an inhibitor of N-linked protein glycosyla tion, and Brefeldin A, an inhibitor of protein trafficking from the Golgi a pparatus, on sycamore (Acer pseudoplatanus L.) cell cultures. These two che micals proved able to induce a strong acceleration of the cell death: chang es in cell and nucleus morphology; an increase in DNA fragmentation, detect able by a specific immunological reaction; and the presence of oligonucleos omal-size fragments (laddering) in DNA gel electrophoresis. Moreover, Brefe ldin A, but not Tunicamycin, strongly stimulated the production of hydrogen peroxide. These results indicate that also in plants chemicals interfering with the activities of endoplasmic reticulum and of Golgi apparatus strong ly induce a form of programmed cell death showing apoptotic features.