Melatonin enhances salt stress tolerance in rubber tree (Hevea brasiliensis) seedlings

•Melatonin improve rubber tree seedlings tolerance to salt stress.•Melatonin enhance salt stress tolerance directly or indirectly by counteracting H2O2 accumulation in rubber tree.•Melatonin enhances salt tolerance by regulating the genes involved in photosynthesis, ROS metabolism, flavonoids and melatonin biosynthesis to counteract the cellular accumulation of H2O2 in rubber tree.