Exploring the physiological and molecular mechanism of Arsenic toxicity and tolerance in rice Oryza sativa L genetypes of Eastern India

Abstract

Arsenic (As), a ubiquitously present trace element is an environmental and food chain contaminant, having chronic and epidemic effects on human and animal health in the South-East Asia. Arsenic is present in both the organic and inorganic forms in the environment. The inorganic forms of the As present in the environment include the pentavalent form, arsenate (HAsO42- or As V) and the trivalent form, arsenite (H2AsO3- or As III). Chronic exposure to As occurs either through contaminated drinking water or food chain. Introduction of As in the food chain takes place by its excessive uptake from soil by plants due to the irrigation with As contaminated water. The major source of human exposure to As is through consumption of As-accumulating crops and vegetables. Arsenic taken up by the plants is translocated and accumulated in the edible plant parts making it a serious worldwide concern to take necessary steps. Rice is a staple food crop for half of the world s population. The Gangetic basin renowned for rice cultivation is severely affected with As contamination. Arsenic-accumulated rice grains are the major source for human-As intake because rice is efficient in assimilating As from the soil. Therefore, searching for rice plants with reduced As levels in their edible parts is the most plausible strategy for decreasing human As intake. The present study intended to evaluate the consequences of As toxicity on morpho-physiological, anatomical, biochemical, nutritional, and yield attributes of the rice genotypes of eastern India with an aim to identify the low As-accumulating rice genotype of this particular region. Understanding the mechanism of As uptake from soil and its transport to the above ground tissues of plants is also required to accomplish the goal. Therefore, the expressions of the candidate genes for As uptake, translocation and detoxification has also been analyzed under different developmental stages and tissues of model plant rice from publicly available microarray data. Tissue-specific expressions