Selenium nanoparticles mitigating arsenic toxicity through modulation in biochemical and anatomical perspectives of Gossypium hirsutum L.

Abstract

Excessive amount of arsenic in agricultural soils and irrigation water deteriorates the production, growth and developments of crops day by day. Cotton cultivation, the most important cash crop in Pakistan, also faces challenges due to arsenic stress. In this study, we observed that As toxicity significantly suppressed seedling growth by decreasing biomass by 59–96% and root/shoot length by 30–50%. However, the application of SeNP (20 mg L⁻¹) improved the biomass by 75–150% and growth by 19–55%, highlighting the strong potential of SeNPs to mitigate As-induced toxicity. Similarly, the chlorophyll a, b, total chlorophyll and carotenoid content decline by 47%, 66%, 54% and 46%, respectively, while the application of SeNP improves these attributes by about 63%, 49%, 62% and 70%, respectively, and restores the photosynthetic efficiency. The arsenic toxicity increases the content of H₂O₂ and MDA by 66% and 57%, respectively. Interestingly, SeNP treatment alleviated oxidative stress by enhancing antioxidant defense and reducing H₂O₂ and MDA accumulation by up to 35% and 26%, respectively. Anatomical studies further confirmed that As toxicity notoriously affects the vascular bundles of the roots and shoots of cotton seedlings. The injury to the vascular bundle and membrane damage were also recovered by selenium nanoparticles. To the best of our knowledge, this is the first report that describes the role of selenium nanoparticles in cotton seedlings for the mitigation of As toxicity through improvements in growth, physiology, antioxidant defense and vascular integrity.