The role of vacuole in the cell death mechanism induced by aluminium (Al) was investigated in tobacco (Nicotiana tabacum L) cell line BY-2. Cells at logarithmic phase of growth were treated without (control) or with Al (up to 150 mu M) in a treatment medium containing CaCl2, sucrose and 2-(N-morpholino) ethanesulfonic acid (MES) buffer (pH 5.0). After 18 h treatment, both the integrity of the plasma membrane (estimated by Evans blue uptake) and growth capacity (estimated by post-Al treatment growth in nutrient medium) were decreased, while the activity of vacuolar processing enzyme (VPE) was increased, in the Al dose-dependent manner. The activity of the vacuole (estimated by neutral red uptake) was slightly increased at 50 mu M then decreased with an increase in Al concentration. Direct observation of morphological changes of vacuole in a transgenic BY-2 expressing GFP-AtVam3p fusion protein localized on tonoplast indicated Al-induced collapse of vacuole. Time-course experiments indicated that both an increase in VPE activity and a loss of growth capacity were clearly observed at 6 h of the treatment time, prior to the loss of plasma membrane integrity. The presence of Ac-YVAD-CHO (an inhibitor effective to VPE) during Al treatment suppressed a loss of plasma membrane integrity. The expression of VPE genes (VPE-1a, VPE-1b) were significantly enhanced by Al treatment Taken together, we conclude that an enhancement of WE activity by Al is controlled at transcriptional level, and is a key factor leading to a loss of integrity of the plasma membrane and a loss of growth capacity. (C) 2013 Elsevier Inc. All rights reserved.