Effective antioxidant defense prevents nitro-oxidative stress under arsenic toxicity: A study in rice genotypes of eastern Indo-Gangetic plains

Abstract

Arsenic (As) toxicity in humans and animals has become a major concern in the last few decades. Rice growing on As-contaminated soil is the principal dietary source of As that poses a significant health hazards to rice patrons, making it a global issue of concern to take necessary steps to counteract the problem. Eastern Indo-Gangetic plains (EIGP) is one of the world’s hotspot for As pollution. Arsenic contaminated irrigation is the principal reason for elevated As levels in the agricultural fields of EIGP, which affects rice productivity. The present study intended to explore the influences of As toxicity (arsenite and arsenate) on the morpho-physiology, ionomics, and biochemical performances of 18 rice genotypes of EIGP at the seedling stage. Arsenic exposure negatively affected plant height, root length, and biomass in rice. It also induced membrane degradation thereby, decreasing total chlorophyll content. It also impaired the nutrient uptake and root-to-shoot translocation abilities of plants. Arsenic toxicity led to the accumulation of reactive oxygen species (ROS) and reactive nitrogen species (RNS) consequently, inducing nitro-oxidative stress in rice. Arsenic tolerance in rice was related to the antioxidant defense system that decreased the malondialdehyde (MDA) content and improved the membrane stability thereby, sustaining plant growth. Additionally, proline facilitated ROS eradication conferring protection against the As-induced nitro-oxidative stress. In this study genotypic variation was obvious in all traits associated with As toxicity. Among the rice genotypes studied, Sahbhagi Dhan and Sabour Ardhjal displayed considerably higher As tolerance with sustainable plant growth, membrane stability, nutrient homeostasis, enhanced antioxidant enzyme activities, lower ROS/RNS and MDA accumulations under different As treatments. Overall, the study revealed the association between proteomic and ionomic profiles in rice to understand the potential adaptive mechanisms in plants under As toxicity.