Extracellular ATP is Involved in the Salicylic Acid-Induced Cell Death in Suspension-Cultured Tobacco Cells

Extracellular ATP (eATP) can function as a signaling molecule to regulate a wide range of cellular processes. We investigated the regulatory role of eATP in the cell death induced by salicylic acid (SA) in suspension-cultured tobacco (Nicotiana tabacum L.) cells. Treatment of tobacco suspension cells with SA induced cell death. The same treatment lowered the levels of eATP, accompanied by a decrease of both the respiratory O-2 uptake and intracellular ATP levels in tobacco suspension cells. Treatment with beta,gamma-methyleneadenosine 5'-triphosphate (AMP-PCP), which is the non-hydrolysable analogue of ATP and can exclude eATP from binding sites of eATP receptors, also induced cell death in tobacco cell cultures. Treatment with exogenous ATP partially alleviated the cell death induced by SA. These observations suggest that eATP is involved in the SA-induced cell death in tobacco cell cultures.