Difference in root-to-shoot Cd translocation and characterization of Cd accumulation during fruit development in two Capsicum annuum cultivars

Abstract

Cultivars of hot pepper (Capsicum annuum L.) vary greatly in their fruit cadmium (Cd) concentration. Previously, we identified a low-Cd (YCT) and a high-Cd (JFZ) cultivar. In this study, we elucidated the physiological mechanisms resulting in the differences in their Cd accumulation. A time-dependent and concentration-dependent hydroponic experiment was conducted to investigate the difference in root-to-shoot Cd translocation between the two cultivars. Furthermore, a pot experiment was carried out to determine the Cd accumulation in all plant tissues of the two cultivars during fruit development. A greater and more rapid root-to-shoot Cd translocation was observed in JFZ. Moreover, the Cd continuously increased in all plant tissues during fruit development, but following fruit development, the fruit Cd concentration decreased in both cultivars. In each cultivar, the Cd accumulated in the fruit was significantly positively correlated with fruit dry weight. JFZ has a higher ability in Cd translocation from roots to shoots via the xylem. The positive correlation between fruit biomass and Cd content supports that the phloem is the major route for Cd loading into developing hot pepper fruits.