Melatonin-mediated nitric oxide improves tolerance to cadmium toxicity by reducing oxidative stress in wheat plants.

Two independent trials were conducted to examine the involvement of nitric oxide (NO) in MT-mediated tolerance to Cd toxicity in wheat plants. Cadmium toxicity considerably led to a decrease in plant growth, total chlorophyll, PSII maximum efficiency (Fv/Fm), leaf water potential, potassium (K) and calcium (Ca). Simultaneously, it caused an increase in levels of leaf malondialdehyde (MDA), hydrogen peroxide (HO), electron leakage (EL), cadmium (Cd) and nitric oxide (NO) compared to those in control plants.

The role of endogenous nitric oxide in melatonin-improved tolerance to lead toxicity in maize plants.

Melatonin (MT) and nitric oxide (NO) are known as scavengers of free radicals and an antioxidant against biotic and abiotic stresses in plant defense systems. However, whether NO interplays role in MT-induced antioxidant defense remains to be determined in the plants exposed to lead (Pb) toxicity. So, two experiments were designed to evaluate the role of NO in MT-mediated tolerance of maize plants to Pb stress.