Reducing Arsenic Accumulation in Rice Using Physiology, Genetics and Breeding

Abstract

AbstractArsenic accumulation in rice grains is a serious public health concern worldwide. Developing arsenic-depleted rice varieties is an effective solution to minimize arsenic exposure through food. Recently, progress has been made in understanding arsenic soil uptake, subsequent transport from root to shoot to grains, vacuolar sequestration and detoxification of arsenic in rice. Many genes controlling major physiological processes such as arsenic speciation within plants have been cloned and characterized. Quantitative trait loci responsible for arsenic accumulation have been identified from several crosses. Transcriptome studies have elucidated the roles of transcription factors, small and micro-RNAs, including long non-coding RNAs in genetic regulation of arsenic stress response in rice. Here we review arsenic uptake, speciation, vacuolar sequestration and transport within plants, including identification of genes controlling each step. We discuss the variation and genetic basis of arsenic accumulation including quantitative trait loci mapping, and the role of transcription factors and small and micro-RNAs in genetic regulation of arsenic stress response. Finally, we discuss the strategies for developing low grain-arsenic rice varieties emphasizing on marker assisted breeding. We also discuss the progress in transgenic approach including its limitations, and the possible applications of genome editing for reducing arsenic accumulation in rice grains.KeywordsArsenicRiceHeavy metalsTransportersPhytochelatinsVacuolar sequestrationNodulin 26- like intrinsic proteinsArsenic reductaseTransgenicsGenome editing