Effects of 24-epibrassinolide and 28-homobrassinolide on iron plaque formation and the uptake of As and Cd by rice seedlings (Oryza sativa L.) in solution culture

The effects of 24-epibrassinolide (Br24) or 28-homobrassinolide (Br28) on the formation of iron plaque (IP) and the uptake of As and Cd by rice plant are poorly understood. Thus, the current work was performed to examine the impacts of Br24/Br28 (10(-8) M) application on IP formation (50 mg Fe2+ L-1 supply) and their interactions on As and Cd accumulation in rice seedlings exposed to As (III) (0.5 mg L-1) and/or Cd (0.5 mg L-1) stresses by a hydroponic experiment. The results showed that the combination of Br24/Br28 and IP induction decreased rice biomass, but markedly promoted IP formation and Fe concentrations in rice plant in comparison with single IP induction. Under Cd stress, IP induction significantly reduced Cd concentrations in shoots by 31% and root tissues by 51%, but the combinations of IP induction and Br24/Br28 promoted Cd concentrations in shoots, root tissues and root surface under Cd or As+Cd treatments. Under As stress, Br24 or IP induction did not affect As concentrations in root tissues and root surface, but markedly decreased that by 27% and 48% in shoots. Under As or As+Cd treatments, the interactions between IP induction and Br24/Br28 significantly enhanced As concentrations on the root surface and decreased that by 14%-50% in shoot. Our results demonstrate that Br24/Br28 application plays vital roles in promoting iron plaque formation and regulating As and Cd accumulation in rice plant. (c) 2020 Elsevier B.V. All rights reserved.