325 - Bioelectrochemical studies of ionic influence on transport characteristics of primary root of Zea Mays

Abstract

The bioelectric potential (BEP r) was measured on root segments of Zea mays which acted as a membrane separating two electrolyte solutions ( m 1, m 2). The BED r was measured in the absence ( m 1 = m 2) and presence ( m 1 ≠ m 2) of a concentration gradient for chloride salts (NH 4Cl, LiCl, NaCl, KCl) and HCl. The relationship BEP r  f (−>log m 2) was non-linear, thereby excluding the diffusion potential as the main cause of biopotential generation. Roots treated with DNP showed a dramatic decrease of potential and a shift of zero potential value to lower concentrations. A parallel flame photometry analysis performed on intact roots revealed changes of internal Li + and K + concentrations in normal roots (low—salt) and K + concentrations in roots treated with DNP or killed with a cytological fixative. It was shown that the isotonic point of K + in normal roots coincides with the BEP ro point in the case of KCI. The difference between these two points in case of LiCl was assigned to internal K + contribution to the electrical isopotential. The comparison of biopotential and concentration data points to an active component of ionic transport in roots of Zea mays.