CN(-)-Induced degradation of nuclei in cells of pea leaves

Degradation of nuclei in epidermal and guard cells of pea leaves was induced by NaCN. Guard cells were considerably more resistant to CN- than epidermal cells. CN--induced nucleus degradation in guard cells was accelerated by illumination. The effect of illumination was negligible in epidermal cells that, unlike guard cells, do not contain chloroplasts. These data may indicate a role of chloroplasts in CN--induced cell death. CN--induced nucleus degradation in epidermal cells was retarded by antioxidants (butylated hydroxytoluene and vitamin E). The effect of CN- in guard cells was largely removed by vitamin E. Salicylic acid, an inhibitor of catalase and ascorbate peroxidase, induced 100% degradation of nuclei in epidermal cells but did not significantly affect nuclei in guard cells. CN--induced inhibition of catalase and peroxidase is assumed to lead to generation and accumulation of reactive oxygen species inducing apoptosis. Like mitochondria, which play an important role in animal cell apoptosis, chloroplasts may take part in apoptosis in plant cells.