Journal Article Kinetic Analysis of Zinc/Cadmium Reciprocal Competitions Suggests a Possible Zn-Insensitive Pathway for Root-to-Shoot Cadmium Translocation in Rice

Fontanili, Laura  ,  Lancilli, Clarissa  ,  鈴井, 伸郎  ,  Dendena, Bianca  ,  尹, 永根  ,  Ferri, Alessandro  ,  石井, 里美  ,  河地, 有木  ,  Lucchini, Giorgio  ,  藤巻, 秀  ,  Attilio Sacchi, Gian  ,  Francesco Nocito, Fabio

9p.16 , 2016-09 , Springer
ISSN:1939-8425
Description
Cadmium (Cd) and zinc (Zn) translocation in rice was studied by analyzing a complete set of competition experiments in which plants were exposed to increasing Zn external concentrations (0.1, 1, and 10 µM), in the absence or presence of 0.1 µM Cd2+, or to different Cd concentrations (0, 0.01, 0.1, and 1 µM) in the presence of 1 µM Zn2+. Results revealed the lack of a full reciprocity when considering the effect of Cd on Zn accumulation, and vice versa, since the accumulation of Zn in the shoots was progressively inhibited by Cd increases, whereas that of Cd was only partially impaired by Zn. Such behaviors probably involved the mechanisms of Cd-xylem loading, as suggested by: i) the analysis of Zn and Cd content in the xylem sap performed in relation to the concentration of the two metals in the mobile fractions of the roots; ii) the analysis of the systemic movement of 107Cd in short term PETIS experiments. From these results we suggest that at least two pathways may mediate root-to-shoot Cd translocation in rice. The former could involve OsHMA2 as Zn2+/Cd2+ xylem loader, whereas the latter appears to involve a Zn-independent system that still needs to be identified.

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