Structural and functional changes in root cells induced by calcium ionophore A23187

The shifts of Ca2+, K+ and proton homeostasis of wheat (Triticum aestivum L . M. cv Ljuba) root cells induced by the Ca2+-ionophore A23187 caused diffe rent responses, depending on the time of exposure to the ionophore. Oxygen consumption and heat production by roots were increased when the Ca2+-speci fic effect of A23187 was expressed. Ultrastructural re-organization of cell organelles was found to follow the ion shifts. The endoplasmic reticulum, Golgi apparatus and mitochondria rearranged their membranes following treat ment. The increased ion permeability of root cell membranes is proposed to cause an excessive energy expenditure for the restoration of ion homeostasi s.