CHROMATIN FRAGMENTATION ASSOCIATED WITH APOPTOTIC CHANGES IN TOBACCO CELLS EXPOSED TO COLD STRESS

Programmed cell death (PCD) may be triggered by a variety of environme ntal stimuli, In this report we show that low temperature treatment of tobacco BY-2 cells results in specific chromatin changes, The early s tage was characterised by chromatin condensation associated with speci fic endonucleolytic cleavage of the genome into fragments of 50-100 kb p in size, Later, after 2 weeks of the cold treatment, a ladder of nuc leosomal units (178 bp) and their multiples occurred, Chromatin change s mere accompanied by a general decrease in cell viability, However, t he cell culture retained about 11% of living cells even after prolonge d incubation in the cold suggesting the presence of a cold-resistant p opulation of cells, The results support the view that PCD was activate d by the cold stress, We suggest that cold-stressed tobacco BY-2 cultu re might be a useful system for investigation of PCD in plant cells. ( C) 1997 Federation of European Biochemical Societies.