What role does cell membrane surface potential play in ion-plant interactions

摘要

Almost all cell membrane surfaces (CMS) are intrinsically negatively charged. These negative charges create a surface electrical potential (Ψ0) which affects ion concentrations at the CMS and consequently affects the phytotoxicity of metallic cations and metalloid anions in different ways. The Ψ0 is also controlled by the ionic composition of the bulk-phase medium (BM). Common cations, especially H⁺, Ca²⁺ and Mg²⁺, can reduce the negativity of Ψ0 by ionic screening and binding. Treatments that reduce the negativity of Ψ0 would reduce the surface activity of Cu²⁺ ({Cu²⁺}0) and increase the surface activity of arsenate ({As(V)}0) at the CMS, and consequently alleviation of Cu²⁺ toxicity but aggravation As toxicity would be expected. It is the Ψ0, rather than site-specific competition, that plays the principal role in ionic interactions and biotic effects.