Effect of brassinosteroid and selenium on uptake and accumulation of chromium in yellow flag (Iris pseudacorus)

Abstract

A hydroponic experiment was conducted to investigate the effect of brassinosteroids (Br) and selenium (Se) on iron plaque (IP) formation and chromium (Cr) accumulation and uptake by Iris pseudacorus L. (yellow flag). Yellow flag seedlings (4 week old seedlings) were grown under 0.1 mg L-1 Br (24-epibrassinolide (Br24) or 28-homobrassinolide (Br28)) or 0.5 mg L-1 Se (Se(IV) or Se(VI)) for 2 weeks. Then seedlings with or without IP induction (60 mg Fe2+ L-1 for 3 days) were exposed to 5 mg L-1 hexavalent chromium [Cr(VI)] for 1 week. The results showed that Cr reduced Fe accumulation and uptake by yellow flag with or without IP; however, this effect was significantly neutralized by Br, but not by Se. IP significantly enhanced Cr accumulation in DCB extract and the whole yellow flag seedling, and increased Cr content by 36%. Br24 and Br28 significantly enhanced Cr accumulation and uptake by yellow flag and increased Cr enrichment by 36 and 51% in the absence of IP, and 7 and 21% in the presence of IP, respectively. Se(IV) markedly improved Cr accumulation in the root, but Cr accumulation and uptake in the shoot and DCB extract were not affected by Se(IV) and Se(VI). Our study suggests that Br24 and Br28 can alleviate Fe loss caused by Cr stress and increase Cr accumulation and uptake by yellow flag seedlings.