Genome-Wide Analysis and Functional Characterization of the NRT1 Gene Family in Grapevine (Vitis vinifera L.) Reveals Roles of VvNRT1.19 and VvNRT1.47 in Salt Stress and Nitrogen Response

Background The NRT1 (nitrate transporter 1) family is referred to as the NPF (nitrate/peptide transporter family). It constitutes the largest and most functionally diverse group of nitrate transporters in plants and plays an essential role in nitrate translocation and allocation. These are fundamental to plant growth, development, and stress adaptation. However, a comprehensive genome-wide characterization of this family in grapevine ( Vitis vinifera L.) remains unexplored. Results A total of 65 NRT1 genes were identified in the grapevine genome and phylogenetically classified into five distinct clades. Their physicochemical properties, as well as gene and protein structural features, were analyzed in detail. Homology analyses revealed that both segmental and tandem duplication events played major roles in driving the expansion of the VvNRT1 gene family. In addition, analysis of tissue-specific expression patterns and cis-regulatory elements suggested that VvNRT1 genes participated in the regulation of grapevine development and adaptive responses to diverse environmental stresses. Nitrate treatment and salt stress induced the expression of multiple VvNRT1s , among which VvNRT1.19 and VvNRT1.47 exhibited the most pronounced transcriptional upregulation. The expression levels of these two genes were positively associated with nitrogen uptake capacity and salt tolerance in grapevine. Furthermore, heterologous overexpression of VvNRT1.19 and VvNRT1.47 in Arabidopsis significantly enhanced nitrogen use efficiency and salt tolerance, thereby promoting plant growth and improving stress resistance. Conclusion This study presents a comprehensive characterization of the VvNRT1 gene family and provides insights into its evolutionary history in grapevine. VvNRT1.19 and VvNRT1.47 are proposed to function as positive regulators of plant responses to stress. Collectively, these findings establish a solid foundation for future functional investigations of NRT1 genes and highlight their potential roles in improving nitrogen regulation and salt stress tolerance in grapevine.