A TILLING rice ATT1 enhances arsenic tolerance by increasing vacuolar sequestration capacity of arsenic

Elevated metalloid arsenic content in rice (Oryza sativa) poses a serious risk to human health. Strategies for reducing accumulation of As in the aerial shoot and grain are critical targets for rice breeding programs. Using a forward genetics approach, we isolated an arsenic-tolerant type 1 (ATT1) from a rice TILLING population using gamma-ray irradiation. ATT1 plants exhibited significantly increased root and aerial shoot biomass by increasing cell proliferation and cell size. Increased cell size in root tissues and significant increases in transcription abundances of As transporters and PC-synthases resulted in maximized vacuolar sequestration of As, which might reduce As toxicity and minimize root-to-shoot translocation of As in ATT1. Resequencing and coexpression module analyses suggest that a single amino acid change on nitrate transporter 1/peptide transporter (OsNPF5.8) might be one of the putative casual genes involved in As tolerance phenotype of ATT1 mutant. This ATT1 mutant line could be an important resource for enhancing rice safety in As-contaminated paddy fields.