Effect of calcium on the absorption and translocation of heavy metals in excised barley roots: Multi-compartment transport box experiment

Abstract

SummaryThe effect of Ca on the absorption and translocation of Mn, Zn and Cd in excised barley roots was studied using a multi-compartment transport box technique. A radioisotope (54Mn, 65Zn or HsmCd)-labelled test solution was supplied to the apexes of excised roots and the distribution pattern in the roots was examined in the absence or presence of Ca. Results obtained were as follows.Addition of Ca to the test solution reduced the absorpIion of Mn and inhibited drastically its translocation in excised roots. With increasing concentrations of Ca in test solutions, its inhibitory effects on the absorption and translocation of Mn became severe.Similar results were observed for the absorption and translocation of Zn. Ca in the test solution decreased the absorption and inhibited drastically the translocation of Zn; as in the case of Mn, higher concentrations of Ca had severe effects on these functions.It was also evident that the addition of Ca to the test solution reduced the absorption of Cd at all levels of Cd concentration (1, 10, and 100#M). Cd absorption decreased with increasing concentrations of Ca in the test solution. However, Ca accelerated the translocation of Cd in excised roots supplied with test solutions containing up to 10#M Cd. At 100gM Cd, addition of Ca caused a negligibly small acceleration of Cd translocation.The accelerating effect of Ca on Cd translocation, especially "xylem exudation", decreased markedly with the addition of 2,4-dinitrophenol, but not with the addition of chloramphenicol or p-chloromercuribenzene sulphonic acid. When barley plants were supplied with only CaSO 4 during the entire growing period, that is, plants were not supplied with nutrient solution on the last day of this period, Ca had no accelerating effect on Cd translocation in excised roots.

Interactions between Ca, Na, and K inSalicornia virginicaand barley roots under saline conditions: multi- compartment transport box experiment

“…2), as described in a previous paper (Kawasaki and Moritsugu 1987): the portion of ions which accumulated in the apex (accumulation), the portion which was translocated and redistributed along the root (redistribution), the portion which moved outward across the cortex (cortical effiux), and the portion which exuded into the external solution through the cut end of the root (xylem exudation). The sum of these portions refers to the total amount From the data presented in Figs.…”

“…1). A detailed description of this plexiglass apparatus was given in previous papers (Kawasaki et al 1983b(Kawasaki et al , 1984Kawasaki and Moritsugu 1987). Excised roots of Salicornia and barley were set horizontally so that the apical part of the root was put in compartment I and the basal cut end in compartment IV (Fig.…”

Effects of metabolic inhibitors on Na+stimulated K+uptake in salicornia virginica roots: Possibility of metabolic coupling of the transport

“…It had been previously reported (Kawasaki and Moritsugu 1987;Sopandie et al 1990) that the distribution pattern of ions in an excised plant root can be classified qualitatively as indicated in Fig. 1.…”

“…Control treatments for this study consisted of a similar addition of 95% ethanol. The present investigation was carried out according to the procedure described previously (Kawasaki and Moritsugu 1987;Sopandie et al 1990). …”

“…In the present study, multi-compartment transport boxes were used to determine the mobility of the ion in the roots (Kawasaki et al 1983;Kawasaki and Moritsugu 1987;Sopandie et al 1990). …”