Genome-wide transcriptome profiling of genes associated with arsenate toxicity in an arsenic-tolerant rice mutant.

The presence of arsenic (As) in polluted environments, such as ground water, affects the accumulation of As in rice grains and causes a serious threat to human health. However, the precise molecular regulations related to As toxicity and tolerance in rice remain largely unknown. In the present study, we developed an arsenic-tolerant type 1 (ATT1) rice mutant by γ-irradiation mutagenesis and performed genome-wide transcriptome analysis for the characterization of As-responsive genes. Toxicity inhibited transcriptional regulation of putative genes involved in photosynthesis, mitochondrial electron transport, and lipid biosynthesis metabolism in wild-type (WT) and ATT1 rice mutant. However, many cysteine biosynthesis-related genes were significantly upregulated in both plants. We also attempted to elucidate the putative genes associated with As tolerance by comparing transcriptomes and identified ATT1-specific transcriptional regulation of genes involved in stress and RNA-protein synthesis. This analysis identified 50 genes that had DNA polymorphisms in upstream regions that differed from those in the exon regions, which suggested that genetic variations in the upstream regions might enhance As tolerance in the mutants. Therefore, the expression profiles of the genes evaluated in this study may improve understanding of the functional roles of As-related genes in response to As tolerance mechanisms and could potentially be used in molecular breeding to limit As accumulation in rice grains.