Supplementation with Ascophyllum nodosum extracts mitigates arsenic toxicity by modulating reactive oxygen species metabolism and reducing oxidative stress in rice

Ascophyllum nodosum extract (ANE) is considered as an effective source of biostimulants that have the potential of ameliorating the negative impact of different abiotic stresses in plants. Considering the growth-promoting ability and other regulatory roles of ANE, the present investigation was executed to evaluate the role of ANE in conferring arsenic (As) tolerance in rice (Oryza sativa L. cv. BRRI dhan89). Rice seedlings (35-d-old) were exposed to two doses of sodium arsenate (As1 − 50 mg As kg–1 soil; As2 − 100 mg As kg–1 soil) at 25 days after transplanting through irrigation, whereas only water was applied to the control. Foliar application of 0.1% ANE was also supplemented under control as well as As-stressed conditions at 7 days intervals for 5 times. Arsenic-induced oxidative stress was evident through a sharp increase in lipid peroxidation, hydrogen peroxide, methylglyoxal, and electrolyte leakage in the As-treated plants. As a consequence, plant growth and biomass, leaf relative water content, as well as yield attributes were reduced noticeably. On the other hand, ANE supplemented plants accumulated enhanced levels of ascorbate and glutathione, their redox balance, and the activities of antioxidant and glyoxalase enzymes viz. ascorbate peroxidase, monodehydroascorbate reductase, dehydroascorbate reductase, glutathione reductase, catalase, glutathione peroxidase, and activities of glyoxalase I and glyoxalase II, respectively. Furthermore, relative water content, plant growth, yield attributes and yield were increased in the As-treated rice plants with ANE supplementation. The results reflected that foliar spray with ANE alleviated As-induced oxidative stress in rice plants by modulating the antioxidative defense and glyoxalase system. •Arsenic (As) stress resulted uncontrolled generation of reactive species in rice plants.•Application of Ascophyllum nodosum extracts (ANE) improved plant growth and water relations under As stress.•Application of ANE maintains ascorbate-glutathione pool under As stress.•Application of ANE upregulates the activities of antioxidant enzymes under As stress.•ANE minimized yield reduction in rice due to As stress.