Role of Suaeda salsa SsNRT2.1 in nitrate uptake under low nitrate and high saline conditions

Abstract

The global annual loss in agricultural production resulting from soil salinization is significant. Although nitrate (NO3−) is known to play both nutritional and osmotic roles in the salt tolerance of halophytes, it remains unclear how halophytes such as Suaeda salsa L. take up NO3− under saline conditions. In the present study, the gene of nitrate transporter 2.1 (SsNRT2.1) was cloned from S. salsa and its function was identified in both S. salsa and Arabidopsis thaliana under salinity and low NO3−-N (0.5 mM NO3−) conditions. The results revealed that SsNRT2.1 expression and NO3− concentration in the roots of S. salsa were higher at 200 mM NaCl, compared with that at 0 and 500 mM NaCl after 24 h treatment. The Arabidopsis overexpression lines showed a higher NO3− content compared to the WT lines at 0 and 50 mM NaCl. A similar trend was observed in the root length. In conclusion, salinity promoted the SsNRT2.1 expression in S. salsa, suggesting that this gene may contribute to the efficient NO3− uptake in S. salsa under low NO3− and high salinity conditions. This trait may explain why S. salsa can tolerate high salinity and produce the highest biomass at about 200 mM NaCl.