Differential expression of arsenic transporters across growth stages determines arsenic accumulation in rice cultivars.

Abstract

Arsenic (As) contamination in rice poses a serious concern, particularly in South and Southeast Asia, where rice is the primary staple food. Therefore, it is critical to understand As uptake mechanisms across growth stages and varieties to minimize As in grains. This study investigated the dynamics of transporters involved in arsenite [As (III)] (OsLSi1 and OsLSi6) and arsenate [As (V)] (OsPT1, OsLSi2, and OsPT2) translocation and vacuolar sequestration (OsABCC1) in two rice (Oryza sativa L.) varieties with distinct genetic and physiological traits (Shatabdi and Rajalaxmi), across six stages from seedling to maturity. OsLSi1 and OsPT1 were upregulated at the vegetative stage, peaking at the jointing stage in Shatabdi (2^-ΔΔCt = 127.35) and at the heading stage in Rajalaxmi (2^-ΔΔCt = 274.2). Consequently, total As accumulation was promoted into roots, resulting in the highest As concentrations, with 18.6 and 23.8 mg kg⁻¹ in Shatabdi and Rajalaxmi, respectively at these stages. Furthermore, OsLSi2, OsLSi6 and OsPT2 expression increased sharply (150.6, 99.0, and 404.0%, respectively) from jointing to heading stage and dropped suddenly at dough stage in Shatabdi. In contrast, Rajalaxmi exhibited a gradual increase in transporter expression from jointing to the dough stage. Speciation analysis showed [As (V)] as the predominant form in grains, accounting for 39.8 and 42% of total As in Shatabdi and Rajalaxmi, respectively. The jointing and dough stages were critical for As accumulation in Shatabdi and Rajalaxmi, respectively. These findings indicate that stage-targeted irrigation and nutrient management during the critical accumulation stages can reduce As in rice grains.

Graphical abstract:

Supplementary information: The online version contains supplementary material available at https://doi.org/10.1007/s12298-026-01819-y.