Entry of a basic protein, lysozyme, through the region of elongation in roots of <italic>Iasione montana</italic>

Abstract

Ultrastructural effects of a basic protein, lysozyme, on root cells of Iasione montana have been related to cellular mechanisms of root growth inhibition. Lysozyme is found to disrupt cell walls and to disintegrate cellular membranes of elongating cells, but not membranes of mature and meristematic cells. Lysozyme seems to penetrate roots only in the region of elongation and does not affect meristematic cells; meristematic cells of Iasione montana possess very thick peripheral cell walls covered by an electronopaque layer. As the cells elongate, primary cell walls become thinner, the microfibrillar network becomes looser and the dense layer breaks off. Elongating cells are more vulnerable to penetration by lysozyme; however, as the cells mature, there is a barrier to lysozyme formed that consists of secondary cell walls; these appear to be a tightly arranged network of macromolecules.