Efficient nitrogen (N) uptake is critical for crop yield, but soil salinization inhibits plant nitrogen acquisition. In this study, the nitrate (NO3 -) transporter gene SsNRT2.5 and its promoter from the halophyte Suaeda salsa was investigated to elucidate the functional role in NO3 - transport under salinity and low NO3 --N conditions. SsNRT2.5 and its promoter were cloned and transformed into Arabidopsis thaliana and rice (Oryza sativa L.) for functional identification, which included analyses of expression patterns, promoter cis-element characterisation and phenotypic assessments under salt and low NO3 --N conditions. SsNRT2.5 expression was significantly upregulated under salt stress and low NO3 --N conditions in S. salsa, which improved NO3 - transport in trangenic Arabidopsis thaliana and rice. Its promoter contained salt-responsive (e.g., GT-1, DRE) and N-related (e.g., GATABOX) elements, which drove stronger salt-induced NRT2.5 expression than AtNRT2.5 promoter. Transgenic Arabidopsis and rice with SsNRT2.5 and its promoter showed enhanced NO3 - accumulation, reduced Na+ toxicity, and higher salt tolerance, as well as improved seed NO3 - storage and viability compared to WT. SsNRT2.5 plays a key role in the adaptation of S. salsa to high saline and nitrogen-limited environments, offering valuable genetic resources and theoretical insights for breeding salt-tolerant crops and developing sustainable saline agriculture.
Keywords: SsNRT2.5; Suaeda salsa; low nitrogen; nitrate transport; salt tolerance.
© 2026 The Author(s). Plant Biotechnology Journal published by Society for Experimental Biology and The Association of Applied Biologists and John Wiley & Sons Ltd.