Genome-wide identification, evolution, and expression analysis of StNRT (nitrate and peptide transporter) gene family in potato (Solanum tuberosum L.).

BACKGROUND: Nitrate and peptide transporters play crucial roles in the uptake, and allocation of nitrate in plant cells and tissues. They are essential in the utilization of nitrogen, as well as in plant development, crop production and yield formation. The NRT family (Nitrate Transporter/Peptide Transporter familiy, NRT/NPF) is one of the largest transporter families in the plant kingdom. Some family members have been extensively studied in thale cress (Arabidopsis thaliana) and rice (Oryza sativa). Although it has been reported in potatoes, it has not been comprehensively and systematically analysed yet. The purposes of this research were to comprehensively identify the NRT genes in the potato genome, to systematically analyze the gene structure, chromosomal distribution, and cis-elements in promoter regions, to identify protein conserved domains and motifs, and to study the expression profile of the StNRT gene in different tissues and under nitrogen stress. RESULTS: Bioinformatics and transcriptome analyses of the StNRT gene family were conducted to dissect the structure, evolution, and expression of the StNRTs in Solanum tuberosum L. In total, 81 StNRT genes were identified and classified into 4 clades. Chromosomal localization analysis revealed that the 81 StNRT genes were located on 12 chromosomes of potato. Among these genes, 2 pairs of genes (StNRT53/56 and StNRT61/62) were predicted to be tandemly duplicated genes, and 8 pairs of genes were segmentally duplicated genes. The collinearity analysis revealed that the StNRTs in potato were closely related to the SlNRTs in tomato. The expression profiles of the StNRTs in different tissues and under different nitrogen conditions revealed distinct spatial expression patterns of these genes and their potential roles in response to various nitrogen conditions. Multiple StNRT genes exhibited differential expression in the roots, stems, and leaves of Qingshu 9 and Xiazhai 65 potato seedlings, indicating their potential key roles in regulating nitrate uptake in potato. CONCLUSIONS: This study systematically characterizes the gene structure, conserved protein domains and motifs, evolutionary relationships, and expression profiles of the StNRT gene family in S. tuberosum. These findings provide critical insights into the functional mechanisms of StNRTs, and identify candidate genes for improving the nitrogen use efficiency (NUE) in potato cultivation.