LAUSR

Health risk caused by Cd containing food is concerned worldwide. Interaction between Mn and Cd has been widely studied in normal hydroponic solution with high ion activities, e.g., the study on sharing of transporter Natural Resistance-Associated Macrophage Protein 5 (OsNRAMP5) between Mn and Cd in rice. However, interaction of Mn and Cd in crops like rice and spinach at field ion activity level is still unknown. Thus, ethyleneglycoltetraacetate (EGTA)-buffered solution experiment was conducted in this work to explore the effect of Mn on the uptake and accumulation of Cd and other mineral elements in rice and spinach. In rice, antagonism of Mn and Cd was only observed in roots at deficient and toxic levels of external Mn2+ activities. Compared with those at Mn2+ sufficiency (pMn2+ 6.7-5.3), average root Cd elevated significantly by 1.85-3.05 times at Mn2+ deficiency (pMn2+ 8.2), while decreased by 1.57-2.59 times at Mn2+ toxicity (pMn2+ 4.8). The antagonism between Mn and K/Mg in rice shoots might be caused by their common role in physiological processes in plants. Antagonism of Mn/Ni in spinach in this work was consistent with their shared transporters in dicots as reported. Results about the antagonism of root Cd/Mn at Mn2+ deficiency suggested that sufficiently available Mn2+ is significant to reduce Cd uptake in rice under field level of ion activity, while it was not for spinach since the change of tissue Cd was insignificant with the increase of Mn2+ activity from deficiency to toxicity. This article is protected by copyright. All rights reserved.