Varietal variation of the relationship between translocation ability of Cd to aerial part and Cd distribution in the root tissue

Abstract

Field and market-basket study in Japan revealed that about seven percent of eggplant (Solanum melongena) exceeded CODEX Cd standard, 0.05 mg/kg. Grafting eggplant onto root stock Solanum torvum reduce Cd concentration in eggplant fruit to one-forth. In spite of the fact that Cd concentration in root was same, those in xylem sap were lower for S. torvum than for S. melogena. Therefore, in the root of S. torvum, Cd transport can be inhibited in the path from epidermides to xylem vessel. In order to identify the root tissue that regulate xylem loading, it should be effective to determine Cd distribution of root section in micro-meter scale. The application of synchrotron X-ray fluorescence microprobe enables us to detect Cd localized in the root tissue. We will introduce our recent results of micro-scale Cd imaging of root tissues, obtained at BL37XU, SPring-8.