Alleviation of arsenic toxicity-induced oxidative stress in lemon grass by methyl jasmonate

Arsenic (As) is a toxic and non-essential metalloid, with known detrimental effects on sustainable agricultural production. Therefore, this study assessed the negative effects of As on lemon grass and how methyl jasmonate (MeJA) mitigated those effects. Interestingly, lemon grass showed no toxicity symptoms under mild As-stress, however plants under severe stress showed early senescence and chlorosis, indicating a decrease in nitrogen content under As-treatment. The results revealed that various physiological and biochemical mechanisms were negatively affected by As-induced oxidative stress. The high production of reactive oxygen species (ROS) such as hydrogen peroxide (H2O2) (8.3-fold), hydroxide ion (OH−) (5.4-fold), superoxide radicals (O2−) (5.2-fold), malondialdehyde (MDA) (2.9-fold), and methylglyoxal (MG) (3.7-fold) caused oxidative injury to lemon grass undergoing As-stress (120 mM). To ameliorate the ROS- and MG-induced oxidative damages, the glutathione-ascorbate (GSH-AsA) cycle and its related antioxidants played a crucial role in ROS detoxification under high As stress. Furthermore, the results revealed that ROS- and MG-induced oxidative stress negatively impacted the metabolic profile of lemon grass under As stress. The ROS- and MG-induced oxidative damage resulted in lowering antioxidants, proline, organic acids, proteins, and amino acids content. Additionally, the current study demonstrated the usefulness of exogenous MeJA application, which considerably improved the plants’ antioxidant defense system and metabolic profile wgich resulted in the reduction of ROS and MG levels by neutralizing the ROS- and MG-induced oxidative damage under As-stress in lemon grass. Collectively, the current study provided insights into the physiological and biochemical pathways of the As-mediated ROS- and MG-induced oxidative damage in lemon grass and its mitigation through exogenous MeJA application.