Overexpression of SsNRT1.1D gene from Suaeda salsa improves salt tolerance in transgenic tomato plants

Salt stress is a major factor restricting the growth, distribution, and yield of crops. Previous studies on NRT (nitrate transporter) have mainly focused on the nitrogen transport and response to metal ion stress. Suaeda salsa L. is a characteristic halophyte that can grow normally at a salt concentration of 200 mM. In this study, we want to know the S. salsa's NRT-related genes and whether they can improve plant salt stress. So we use bioinformatics and molecular biology to verify our hypothesis. Transcriptome data revealed that the S. salsa NRT1.1D (SsNRT1.1D) gene was upregulated under salt stress. The SsNRT1.1D open reading frame is 1743 bp and has MFS and PTR2 conserved domains. Subcellular localization revealed that SsNRT1.1D is primarily located in the endoplasmic reticulum. qRT-PCR results showed that SsNRT1.1D gene is mainly expressed in S. salsa leaves. The expression of the SsNRT1.1D gene in S. salsa leaves was highest at 12 h after 400 mM sodium chloride (NaCl) treatment. Transgenic tomato plants containing the overexpression vector (35S::SsNRT1.1D) were generated and grown under field conditions to obtain the T-3 generation transgenic tomato seeds. The results showed that transgenic tomato plants had higher salt tolerance than the wild-type plants. Overall, our results demonstrate that the SsNRT1.1D gene can improve plant salt tolerance. This study provides a theoretical basis for improving the utilization of saline-alkaline land and the yield of tomatoes.