Arsenic (As) is a toxic carcinogen so it is crucial to decrease As accumulation in crops to reduce its risk to human health. The transporters for As uptake and metabolism have been elucidated and target genes have been identified in different plants, which may offer effective approaches to reduce As accumulation in plants, especially in some important crops.

Arsenite (AsIII) antiporter ACR3 is critical for As metabolism in organisms, but it is lost in flowering plants. Here, a novel ACR3 gene from As hyperaccumulator Pteris vittata, PvACR3;1, was cloned and expressed in Saccharomyces cerevisiae (yeast), Arabidopsis thaliana (model plant), and Nicotiana tabacum (tobacco). Yeast experiments showed that PvACR3;1 functioned as an AsIII-antiporter to mediate AsIII efflux to an external medium. At 5 μM AsIII, PvACR3;1 transgenic Arabidopsis accumulated 14−29% higher As in the roots and 55−61% lower As in the shoots compared to WT control, showing lower As translocation. Besides, transgenic tobacco under 5 μM AsIII or AsV also showed similar results, indicating that expressing PvACR3;1 increased As retention in plant roots. Moreover, observation of PvACR3;1−green fluorescent protein fusions in transgenic Arabidopsis showed that PvACR3;1 localized to the vacuolar membrane, indicating that PvACR3;1 mediated AsIII sequestration into vacuoles, consistent with increased root As. In addition, soil experiments showed ~22% lower As in the shoots of transgenic tobacco than control.

Based on the above results, we also transformed PvACR3;1 gene into rice (Oryza sativa L.), which is the staple food for half of the world’s population and also an efficient accumulator of As. Similar to Arabidopsis and tobacco, transgenic rice also showed higher As retention in plant roots and lower As translocation to the aboveground tissues. More importantly, When grown in flooded soils with As, expressing PvACR3;1 significantly reduced inorganic As accumulation in brown rice by >20%, significant for controlling As exposure risk from rice. Thus, our study provides a potential strategy to limit As accumulation in rice, shedding light on engineering low-As crops to improve food safety.