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.

Key message: StERF87 directly activates StPR1a via GCC-box binding and integrates SA/ET signaling to enhance bacterial wilt resistance. Potato ( Solanum tuberosum ) is an important food crop worldwide, yet its yield is severely constrained by bacterial wilt caused by Ralstonia solanacearum . We used RNA-Seq to study gene expression in ‘Z1076-1’ at 0, 1, and 2 days post-inoculation (dpi) with R. solanacearum (10⁶ CFU mL⁻ ¹ ). We identified 6663 differentially expressed genes at 1 dpi and 7390 at 2 dpi. Calcium signaling and MAPK cascade genes were upregulated at 1 dpi. PR protein and ROS-related genes showed stronger induction at 2 dpi. The ethylene-responsive transcription factor StERF87 was continuously upregulated. Its expression increased 4.7-fold at 2 dpi, with FPKM values over 100. We selected this gene for functional analysis. Transgenic potato plants overexpressing StERF87 showed lower disease severity and reduced bacterial growth in both whole plants and tuber slices. StERF87 is a transcriptional activator that directly binds the GCC-box in the StPR1a promoter to activate its transcription. After R. solanacearum inoculation, StERF87 overexpression also increased PR1b1 expression, elevated salicylic acid and ethylene levels, reduced jasmonic acid accumulation, and altered the activities of ROS-scavenging enzymes including SOD, POD, and CAT. These results show that StERF87 regulates potato defense against R. solanacearum and may be useful for breeding bacterial wilt-resistant 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.