Foliar application of allantoin reinforces antioxidant defense and glyoxalase systems to confer tolerance against arsenic toxicity in rice (Oryza sativa L.).

backgroundArsenic (As) contamination is a pressing global challenge that substantially restricts crop productivity and growth due to its increasing prevalence in agricultural soils. Allantoin, a well-characterized plant metabolite, has not been thoroughly explored for its role in mitigating As-induced oxidative stress. This research explored the protective effects of foliar-applied allantoin in rice (Oryza sativa L. cv. BRRI dhan75) exposed to sodium arsenate (0.25 mM). At 10 days after transplanting plants subjected to As, with two allantoin doses (0.5 and 1.0 mM) applied as foliar sprays at 5-day intervals.

resultsArsenic stress significantly inhibited growth, leaf expansion, chlorophyll content and water balance which reduced biomass accumulation, while elevating oxidative damage through higher hydrogen peroxide accumulation, lipid peroxidation, proline overproduction, electrolyte leakage, and suppression of glyoxalase and antioxidant enzyme activities. Conversely, allantoin application markedly alleviated these detrimental effects by improving photosynthetic performance, water status, and redox homeostasis through increased levels of ascorbate and glutathione. Moreover, allantoin activated key antioxidants and glyoxalase enzymes, including glutathione reductase, glutathione peroxidase, catalase, peroxidase, ascorbate peroxidase, monodehydroascorbate reductase, glutathione S-transferases, dehydroascorbate reductase, and glyoxalases.

conclusionsThese results highlight that allantoin reinforces reactive oxygen species scavenging and antioxidant defense machinery, thereby conferring resilience to As toxicity in rice.