Abstract

According to recent reports, millions of people across the globe are suffering from arsenic (As) toxicity. Arsenic is present in different oxidative states in the environment and enters in the food chain through soil and water. In the agricultural field, irrigation with arsenic contaminated water, that is, having a higher level of arsenic contamination on the top soil, which may affects the quality of crop production. The major crop like rice (Oryza sativa L.) requires a considerable amount of water to complete its lifecycle. Rice plants potentially accumulate arsenic, particularly inorganic arsenic (iAs) from the field, in different body parts including grains. Different transporters have been reported in assisting the accumulation of arsenic in plant cells; for example, arsenate (AsV) is absorbed with the help of phosphate transporters, and arsenite (AsIII) through nodulin 26-like intrinsic protein (NIP) by the silicon transport pathway and plasma membrane intrinsic protein aquaporins. Researchers and practitioners are trying their level best to mitigate the problem of As contamination in rice. However, the solution strategies vary considerably with various factors, such as cultural practices, soil, water, and environmental/economic conditions, etc. The contemporary work on rice to explain arsenic uptake, transport, and metabolism processes at rhizosphere, may help to formulate better plans. Common agronomical practices like rain water harvesting for crop irrigation, use of natural components that help in arsenic methylation, and biotechnological approaches may explore how to reduce arsenic uptake by food crops. This review will encompass the research advances and practical agronomic strategies on arsenic contamination in rice crop.

Highlights

  • Arsenic (As) is a toxic metalloid that is ubiquitous in the environment

  • Wide ranges of issues are prevailing related to arsenic content in rice and factors controlling arsenic bioavailability, uptake, accumulation, and toxicity

  • Oxidative stress generated due to production of reactive oxygen species (ROS) after arsenic exposure in plants is counteracted by production and complexation with thiol rich compounds like glutathione and phytochelatins (PCs)

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Summary

Introduction

Arsenic (As) is a toxic metalloid that is ubiquitous in the environment. It has raised serious concern from both environmental and human health perspectives. Rice is the most severely affected staple food crop to arsenic contamination as compared with other crops like wheat, maize, and barley due to its cultivation in flooded conditions as compared to non-flooded for wheat. Under flooding or anaerobic conditions in paddy soils, reductive mobilization of arsenic greatly enhances the bioavailability of arsenic leading to excessive accumulation of this metalloid in rice grain and plant [31]. The pot study by Arao et al [34], further supports the notion that aerobic treatment can effectively reduce the grain arsenic New cultivation methods, such as aerobic rice, alternate wetting and drying, and raised bed cultivation may prove to be highly effective in reducing accumulation of arsenic in rice, because these water-saving methods are likely to maintain soil under more oxic conditions and less arsenic mobilization, and less input of arsenic. An attempt has been made to summarize the data related to arsenic bioavailability to rice from soil, its uptake, accumulation, and oxidative stress in rice and possible cost effective agronomic strategies to reduce arsenic contamination in rice

Uptake and Transport of Inorganic Arsenic Species
Uptake and Transport of Organic Arsenic Species
Accumulation of Arsenic in Rice Grain
Factors Influencing Arsenic Mobilization and Intake in Rice Plant
Effect of Redox Condition and Soil Texture
Effect of Soil pH
Effect of Organic Matter
Genotype Variation in Rice
Arsenic Induced Oxidative Stress and Response in Rice Plant
Concentration of Arsenic Species in Rice Grain
Risk of Arsenic from Rice Diet to Human Health
Agronomic Strategies for Mitigating Arsenic Accumulation in Rice
Fertilization of Soil with Minerals
Role of Fe
Role of Phosphorus
Role of Silica
Role of Sulfur
Water Management and Irrigation Practices
Role of Soil Microorganism
Restriction of Arsenic at Underground Level
Increase AsIII Efflux Rate
Volatilization of Arsenic
Findings
Concluding Remarks
Full Text
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