Aluminium-inhibited NO3– uptake is related to Al-increased H2O2 content and Al-decreased plasma membrane ATPase activity in the root tips of Al-sensitive black soybean

Abstract

In this study, Al-sensitive black soybean (Glycine max (L.) Merr.) specimens were treated in Hoagland solutions containing 50–400 µM Al for 1–4 days. The measurement for NO3– uptake showed that the NO3– uptake decreased gradually as the Al concentration and treatment time increased, suggesting that Al stress significantly reduced the NO3– uptake by soybean. Under 100-µM Al stress for 4 days, the plasma membrane (PM) ATPase activity (inorganic phosphate (Pi) release), H+ pump activity, phosphorylation of PM ATPase and its interaction with 14-3-3 protein in soybean root tips were all smaller than those in the root tips of control plants. The addition of 150 µM Mg2+ in Al treatment solutions significantly alleviated the Al inhibition of NO3– uptake in soybean. The presence of Mg2+ in a 100-µM Al solution pronouncedly enhanced PM ATPase activity, H+ pump activity, phosphorylation of PM ATPase and its interaction with 14-3-3 protein in soybean root tips. The application of 2 mM ascorbic acid (AsA, an H2O2 scavenger) in Al treatment solutions significantly decreased Al-inhibited NO3– uptake in soybean. The cotreatment of soybeans with 2 mM AsA and 100 µM Al significantly reduced H2O2 accumulation and increased the PM ATPase activity, H+ pump activity, phosphorylation of PM H+-ATPase and its interaction with 14-3-3 protein in soybean root tips. The evidence suggested that Al-inhibited NO3– uptake is related to Al-increased H2O2 content and Al-decreased phosphorylation of PM ATPase and its interaction with 14-3-3 protein as well as PM ATPase activity in the root tips of soybean.