Chromatin fragmentation associated with apoptotic changes in tobacco cells exposed to cold stress

Programmed cell death (PCD) may be triggered by a variety of environmental stimuli, In this report we show that low temperature treatment of tobacco BY-2 cells results in specific chromatin changes, The early stage was characterised by chromatin condensation associated with specific endonucleolytic cleavage of the genome into fragments of 50-100 kbp in size, Later, after 2 weeks of the cold treatment, a ladder of nucleosomal units (178 bp) and their multiples occurred, Chromatin changes mere accompanied by a general decrease in cell viability, However, the cell culture retained about 11% of living cells even after prolonged incubation in the cold suggesting the presence of a cold-resistant population of cells, The results support the view that PCD was activated by the cold stress, We suggest that cold-stressed tobacco BY-2 culture might be a useful system for investigation of PCD in plant cells. (C) 1997 Federation of European Biochemical Societies.