Potatoes are a critical staple crop worldwide, yet their yield is significantly constrained by salt stress. Understanding and enhancing salt tolerance in potatoes is crucial for ensuring food security. This study evaluated the salt tolerance of 17 diverse potato varieties using principal component analysis, membership function analysis, cluster analysis, and stepwise regression analysis. Comprehensive evaluation based on morphological, physiological, and biochemical indicators divided the varieties into three categories, identifying Z1264-1, Z700-1, Z943-1, Z1266-1, Z510-1, and Z1076-1 as having strong salt tolerance. Regression equations established stem thickness, root length, and catalase activity as rapid identification markers for salt tolerance in tetraploid potatoes. Transcriptome analysis of the highly tolerant variety Z1076-1 identified 68 differentially expressed miRNAs (DE miRNAs). qRT-PCR validation for eight randomly selected DE miRNAs confirmed consistent expression trends with transcriptome data. Predicted target genes of these miRNAs are involved in calcium channel signaling, osmotic regulation, plant hormone signaling, and reactive oxygen species clearance. Our findings provide valuable insights for the identification and screening of salt-tolerant potato germplasms. The findings also lay the foundation for studying molecular mechanisms of salt tolerance and advancing genetic breeding efforts to cultivate more resilient potato varieties.

Soil-based irrigation and the partial substitution of chemical fertilizers with manure are promising practices to improve water and nitrogen (N) use efficiency. We hypothesize that their combination would simultaneously benefit potato production, tuber quality and profitability. A two-year experiment was conducted in semiarid northern China to investigate the combined effects of three water treatments [rainfed (W0), soil-based irrigation (W1), conventional irrigation (W2)] and three N treatments [no N (N0), chemical N (N1), 25% manure substitution (N2)] on these indicators, and to perform a comprehensive evaluation and correlation analysis. The results showed that water and N treatments separately affected all indicators except vitamin C content. Compared to W2, W1 significantly increased water productivity by 12% and irrigation water use efficiency (IWUE) by 30% due to 10% lower evapotranspiration and 21% lower water use. However, W1 and W2 negatively affected crude protein content. Conversely, this was compensated by the combination with N1 and N2. There were slight differences between N1 and N2 for all indicators on average across water treatments, while under W1, N2 significantly increased leaf area index (LAI) and N recovery efficiency (REN) by 18% and 29.4%, respectively, over N1. Also, comprehensive evaluations showed that W1N2 performed best, with the highest tuber yield, profit and acceptable quality. This can be explained by the increase in LAI, IWUE and REN due to the positive correlations with tuber yield and net return. Consequently, soil-based irrigation combined with 25% manure substitution had complementary effects on tuber quality and synergistic effects on potato productivity and profitability.

Trehalose-6-phosphate phosphatase (TPP) modulates the Trehalose-6-phosphate–trehalose balance, a key regulatory node in plant carbon sensing and stress resilience. However, its functional roles in vegetative crops such as potato (Solanum tuberosum, St) remains poorly understood. Here, we conducted a genome-wide identification of the StTPP gene family and identified nine distinct loci distributed across five chromosomes. Phylogenetic analysis categorized these loci into three clades, supported by conserved HAD-box motifs and distinct exon–intron structures. Family expansion was driven by segmental duplication under purifying selection. In silico promoter analysis revealed cis-elements responsive to hormones, light, and stress, while network modeling identified 64 transcription factors potentially involved in regulating StTPP expression. A biphasic transcriptional response was observed in the salt-tolerant cultivar Xisen6: rapid induction of StTPP2/3/9 early in salt exposure, followed by late repression of most members. Subcellular localization assays indicated that StTPP3 is present in the nucleus and cytosol, suggesting multifunctional roles. These findings suggest that StTPPs integrate developmental and environmental signals, providing a molecular basis for improving potato stress tolerance and yield stability.

β-D-xylosidase (BXL) is a key enzyme involved in xylan degradation and plays crucial roles in plant development and stress responses. However, its functional roles in potato (Solanum tuberosum) remain poorly understood. In this study, we performed a genome-wide identification of the StBXL gene family and identified eight StBXL genes distributed across five chromosomes. A phylogenetic analysis classified these genes into four groups. Conserved motif and domain analyses indicated functional conservation among StBXL proteins. Analyses of cis-acting elements in the promoters and expression profiles of StBXL genes in various plant tissues under different stress treatments revealed their spatiotemporal expression patterns, as well as potential roles in phytohormone signaling and stress responses. Alkali stress significantly inhibited the expression of StBXL4 and StBXL5. The overexpression of StBXL4 enhanced the sensitivity of potato seedlings to alkali stress, whereas the overexpression of StBXL5 showed no significant phenotypic differences under the same conditions. These results suggest that StBXL4 acts as a negative regulator of the alkali stress response in potato. This study fills the research gap regarding the potato StBXL gene family and provides valuable insights for the molecular breeding of alkali-tolerant potato varieties.

Salt stress can trigger endoplasmic reticulum (ER) stress and affect potato yield. The endomembrane system is tightly regulated in response to salt stress for maintaining cellular homeostasis. However, little is known about the genes involved in the ER-mediated cytoprotective pathways in potato plants. Previously characterized genes involved in the ER stress signaling pathway in Arabidopsis were used as prototypes. We identified 29 genes involved in ER stress response in the potato genome. Transcriptome data analysis showed that the expression levels of related genes were significantly different in different tissues. Most genes can response to β-aminobutyric acid, benzothiadiazole, salt, and mannitol. qRT-PCR assay revealed that they could respond to NaCl and tunicamycin, which was consistent with the fact that the promoter region of related genes contained ER-stress- and abiotic-stress-related cis-elements. Furthermore, we found that StbZIP60 has a splicing form, StbZIP60s, under salt and ER stress, which can be spliced at the CxGxxG site in the C terminus to create a frame shift through the excision of 23 base pairs. StbZIP60 is localized in the cytoplasm and nucleus, whereas most of the StbZIP60s translocated to the nucleus. This study provides a basis for further analyses of the functions of salt-stress- and ER-stress-related genes in potato plants.