Membrane-related hallmarks of kinetin-induced PCD of root cortex cells.

KEY MESSAGE: Changes in cellular membrane potential and their fluidisation are the hallmarks of cell death induction with kinetin in root cortex. Programmed cell death (PCD), one of the essential processes in plant development, is still poorly understood. In this paper, the scientific plant model, V. faba ssp. minor seedling roots after kinetin application which triggers off programmed death of cortex cells, was used to recognise membrane-related aspects of plant cell death. Spectrophotometric, reflectometric and microscopic studies showed that the PCD induced by kinetin is accompanied by higher potassium ions leakage from roots, loss of plasma and ER membrane potentials (expressed by their lower amounts and higher index of fatty acid unsaturation), malformation of nuclear envelope, lower total lipid amount and formation of their peroxides, lower amount of phospholipids and changes in their composition. The results showed that potassium ions leakage, expressed in percentage of their amounts, and loss of plasma and ER membrane potential, expressed in percentage of their fluorescence intensity, together with the nuclear chromatin double staining with ethidium bromide and acridine orange, might be direct and universal methods for detecting specific plant PCD hallmarks and estimation of PCD intensity (percentage of dying and dead cells).