The Effect of Histones and Other Basic Macromolecules on Cell Permeability and Elongation of Barley Roots

Low exogenous concentrations of calf‐thymus histone, poly‐l‐lysine and lysozyme inhibit root elongation. These basic macromolecules (polycations) also affect cell permeability resulting in a leakage of ultraviolet light (UV)‐absorbing materials and chloride ion from cells. Adenosine 5′‐monophosphate was identified as one of the UV‐absorbing compounds in the root exudate, by thin layer chromatography. These deleterious effects of polycations on root growth and permeability are reduced in the presence of calcium and other divalent cations. Calcium ion‐histone interaction appears to exhibit competitive kinetics and suggests that both calcium and histone compete for attachment to negative sites on cell membrances.