Pectic Signal Transduction in Carrot Cells: Membrane, Cytosolic and Nuclear Responses Induced by Oligogalacturonides

Oligogalacturonides were applied at a concentration of 0.2 mg ml−1 to Daucus carota cells and protoplasts. Fractions containing oligomers of degree of polymerisation 9 to 16 in the presence of 150 mM NaCl and 0.5 mM CaCl2, and pure oligomers of degree of polymerisation 9 to 13 in the same ionic medium, triggered a cytosolic calcium mobilisation, membrane depolarisation and cytosolic acidification. These membrane and cytosolic events coincided with the accumulation of transcripts encoding phenylalanine ammonia-lyase, catalytic activitation of the enzyme and p-hydroxybenzoic acid accumulation in the cell wall of the elicited cells. The effect of a calcium ionophore, calcium channel blockers, calmodulin inhibitors, phosphatidyl inositol metabolism modulators and H+-ATPase modulators were investigated on oligogalacturonide-induced phenylalanine ammonia-lyase enzyme and gene activation in suspension-cultured carrot cells.