Differential expression of sulfate transporters under selenium supply identifies OsSULTR1;1 as a candidate for nutritional enhancement in super basmati rice.

backgroundSelenium (Se) is an essential micronutrient for humans, yet its dietary availability largely depends on plant-based foods. In rice, Se uptake occurs mainly via sulfate transporters due to the chemical similarity between sulfate and selenate. While the role of transporters such as OsSULTR1;2 has been described in japonica rice, little is known about their regulation in indica aromatic cultivars like Super Basmati, which are naturally enriched in Se and widely consumed across Asia. This study aimed to characterize the transcriptional regulation of OsSULTR genes in Basmati rice under selenate exposure to identify candidate transporters contributing to Se biofortification. METHODS AND

resultsSuper Basmati seedlings were hydroponically grown under varying sulfate and selenate concentrations, and gene expression was analyzed in roots, shoots, and developing grains by qRT-PCR. Se accumulation was quantified using ICP-MS. Among high-affinity transporters, OsSULTR1;1 showed strong induction in root tissues under selenate supply and was persistently expressed in developing grains, indicating dual roles in uptake and grain loading. In contrast, OsSULTR1;2 and OsSULTR1;3 were shoot-specific with minimal induction. Group 3 transporters exhibited variable shoot-specific expression, with OsSULTR3;2 and OsSULTR3;3 showing notable induction during grain development. Se accumulation increased dose-dependently in roots and shoots, with efficient translocation to shoots and progressive enrichment in grains. Uptake was strongly pH-dependent, with maximal absorption at acidic pH (3.5).

conclusionsOur findings highlight OsSULTR1;1 as the primary transporter mediating Se uptake and seed loading in Basmati rice, contrasting with OsSULTR1;2 in japonica rice. This study provides new molecular insights into Se accumulation in aromatic indica rice and identifies OsSULTR1;1 as a promising target for Se biofortification strategies to improve dietary nutrition.