Melatonin alleviates aluminum-induced root growth inhibition by interfering with nitric oxide production in Arabidopsis

•NR- and NOS-dependent NO production contributed toAl-induced root growth inhibition in Arabidopsis.•Al inhibits root growth by NO-mediated reduction of the cell division cycle and the quiescent center cellular activity.•External application of melatonin alleviated Al-induced root growth inhibition.•Melatonin alleviated Al toxicity through interfering with NO production.•SNAT-mediated melatonin synthesis played a critical role in Al resistance.