Plasma membrane intrinsic protein OsPIP2;6 is involved in root-to-shoot arsenic translocation in rice (Oryza sativa L.).

ABSTRACT

KEY MESSAGE This study demonstrates the crucial role of OsPIP2;6 for translocation of arsenic from roots to shoots, which can decrease arsenic accumulation in rice for improved food safety. Arsenic (As) contamination in food and water, primarily through rice consumption, poses a significant health risk due to its natural tendency to accumulate inorganic arsenic (iAs). Understanding As transport mechanisms is vital for producing As-free rice. This study investigates the role of rice plasma membrane intrinsic protein, OsPIP2;6, for AsIII tolerance and accumulation. RNAi-mediated suppression of OsPIP2;6 expression resulted in a substantial (35-65%) reduction in As accumulation in rice shoots, while root arsenic levels remained largely unaffected. Conversely, OsPIP2;6 overexpression led to 15-76% higher arsenic accumulation in shoots, with no significant change in root As content. In mature plants, RNAi suppression caused (19-26%) decrease in shoot As, with flag leaves and grains showing a 16% reduction. OsPIP2;6 expression was detected in both roots and shoots, with higher transcript levels in shoots. Localization studies revealed its presence in vascular tissues of both roots and shoots. Overall, our findings highlight OsPIP2;6's role in root-to-shoot As translocation, attributed to its specific localization in the vascular tissue of roots and leaves. This knowledge can facilitate the development of breeding programs to mitigate As accumulation in rice and other food crops for improved food safety and increasing productivity on As-contaminated soils.