PYR/PYL (pyrroloquinoline quinone resistance/PYR1-like) are receptors for abscisic acid (ABA) in plants and play a crucial role in responses to abiotic stress. In this study, we identified 63 members of the StPYL gene family at the tetraploid whole-genome level in potatoes. We analyzed the physicochemical properties of these 63 StPYLs and constructed a phylogenetic tree using Arabidopsis thaliana and potato (Solanum tuberosum L.) cultivar ‘DM’ as the reference. By examining gene structure, conserved protein motifs, and collinearity, we found that StPYLs are highly conserved throughout evolution. The gene expression heat map under salt stress revealed that 57 StPYL genes are involved in the salt stress response. Among them, the expression level of StPYL9a-like changed significantly under salt stress. Through genetic transformation, we observed that overexpression of StPYL9a-like enhanced the growth and survival of potato plants under salt stress compared to the wild type. The contents of proline (Pro), superoxide dismutase (SOD), and chlorophyll in the leaves of overexpressing plants increased, while malondialdehyde (MDA) levels decreased. This suggests that StPYL9a-like positively regulates salt tolerance by affecting antioxidant enzyme activity and osmotic adjustment substances in potatoes. Subcellular localization demonstrated that StPYL9a-like is localized in the nucleus. This study provides a reference for the functional research of PYLs in potatoes, offers a basis for screening potato genes related to salt stress, and lays a foundation for developing salt-tolerant potato varieties.

The AGC kinase family is crucial for regulating plant disease resistance, integrating hormone signals, managing reactive oxygen species (ROS) metabolism, and maintaining redox balance. However, research on AGC kinases in Solanaceae plants is limited, and the functions of most AGC kinases remain unidentified. Using the tetraploid potato (Solanum tuberosum L.) cultivar ‘Tingsha No. 9’, we conducted a genome-wide identification of the AGC gene family and profiled transcript responses to late-blight (Phytophthora infestans) stress. Additionally, we examined the subcellular localization and characterized the phenotypic responses of overexpression lines of the late-blight–responsive kinase StD6PK under late-blight stress. A total of 141 AGC family members were identified in ‘Qingshu No. 9’, categorized into eight subfamilies. This classification includes one cultivar-specific subfamily that was previously unrecognized, as well as 50 AGC family members within subfamily 1. AGC family members had significant differences in physicochemical characteristics and most of which were located in the nucleus. AGC family members are distributed on 46 chromosomes, with the largest number of chromosome 11 and the least number of chromosome 7. Gene duplication is dominated by whole-genome duplication (WGD) and segmental duplication. Ka/Ks values of all collinear pairs are less than 1. Purification selection drives family evolution in a long evolutionary process. Its promoter is rich in light-responsive, hormone-responsive, and stress-responsive elements, and its expression varies significantly in tissues; and some genes are highly expressed in specific organs. RNA-seq analysis revealed that 78.1% of the members responded to late-blight stress, and the expression levels of the selected eight subfamily members all showed significant increases or decreases after inoculation with late blight. StD6PK (Soltu.Q9.Chr04_A40011450.g) was strongly induced at 48~72 h, and its expression level at 72 h was 5.7 times higher than that at 0 h. Stable transformation of potato demonstrated that overexpression of StD6PK could enhance the resistance of potato to late blight, with subcellular localization revealing its nuclear localization characteristic. This study was the first time to complete the identification of AGC family genome of tetraploid potato ‘Qingshu No. 9’, reveal its evolution and expression characteristics, clarify the response characteristics of StD6PK to late blight, and provide insights into the evolutionary and functional basis of the AGC kinase gene family in potato late blight resistance mechanisms, while supplying genetic resources to accelerate the development of late blight-resistant germplasm.

Potato leaf size directly affects photosynthetic efficiency and yield; therefore, elucidating the genetic regulation of this trait is important for breeding improvement. In this study, a natural population of 476 tetraploid potato accessions was used to evaluate compound leaf size and apical leaflet size. Both traits were scored on a 1–9 ordinal scale in accordance with the national standard GB/T 19557.28-2018. The two-year (2019–2020) phenotypic means showed continuous variation consistent with polygenic quantitative trait architecture. Correlation analysis revealed a strong, highly significant positive association between compound leaf size and apical leaflet size (R = 0.71, p < 2.2 × 10⁻¹⁶). Genome-wide association analysis identified 211 SNPs significantly associated with compound leaf size, predominantly located on chromosomes Chr05 and Chr06, from which 75 candidate genes were identified. KEGG enrichment analysis showed that these candidate genes were significantly enriched in pathways related to RNA degradation, ribosomes, phenylalanine biosynthesis and genetic information processing. Putative candidate genes potentially regulating compound leaf size include DM8C10G01290.1 (Rcd1-like), DM8C11G02500.1 (ADH_zinc_N domain-containing), DM8C10G01180.1 (Ribosomal_S8e domain-containing), DM8C06G16880.1 (Methyltransf_2 domain-containing) and DM8C05G27660.1 (Inositol_P domain-containing). A total of 671 SNP loci were identified as significantly associated with apical leaflet size, primarily localised on chromosomes Chr04 and Chr06, which led to the identification of 175 candidate genes. KEGG enrichment analysis showed that candidate genes for apical leaflet size were mainly enriched in pathways related to energy metabolism, secondary metabolism and plant hormone signal transduction. Putative candidate genes potentially regulating apical leaflet size include DM8C10G13560.1 (Malic_M domain-containing), DM8C01G21400.1 (PPDK_N domain-containing), DM8C08G02250.1 (UDPGT domain-containing), DM8C03G19930.1 (Orn_Arg_deC_N domain-containing), DM8C04G29090.1 (peroxidase), DM8C02G10960.2 (Pro_CA domain-containing), DM8C01G45290.1 (NIR_SIR domain-containing), DM8C08G02280.1 (Glyco_tranf_2_3 domain-containing), DM8C06G27780.1 (UDPGT domain-containing), DM8C06G27490.1 (Transket_pyr domain-containing), DM8C04G23010.1 (LRRNT_2 domain-containing) and DM8C03G01180.1 (BES1_N domain-containing). This study elucidated the genetic basis of potato leaf size and provided promising candidate markers and genetic resources, which require further validation in independent populations and environments before deployment in molecular marker-assisted breeding.

Low-temperature stress significantly limits plant growth, development, and productivity, posing a major environmental constraint. The potato (Solanum tuberosum L.) is particularly vulnerable to low temperatures, underscoring the crucial need to enhance cold tolerance in potato breeding efforts for sustainable production. Basic leucine zipper (bZIP) transcription factors serve as central regulators of plant developmental processes and stress responses; however, their functional role in cold tolerance in tetraploid potato remains poorly understood. Here, we report a systematic characterization of the bZIP gene family in tetraploid potato and provide preliminary evidence that StbZIP104 enhances plant cold tolerance. A total of 191 StbZIP genes were identified and classified into 11 subfamilies, exhibiting uneven chromosomal distribution and expansion primarily driven by whole-genome and segmental duplication. Promoter cis-element analysis, together with GO and KEGG enrichment analyses, indicated that StbZIP genes are broadly associated with hormone signaling, stress responses, signal transduction, and environmental adaptation. Expression profiling under low-temperature treatment revealed eight cold-inducible StbZIP genes (log₂FC ≥ 1 and FDR < 0.05), among which StbZIP104 was strongly induced (log₂FC ≥ 2) and showed 5.36-fold higher expression in highly cold-resistant cultivars than in cold-sensitive cultivars. Subcellular localization confirmed that StbZIP104 is a nuclear-localized protein. Functional validation confirmed that overexpressing StbZIP104 notably improved cold tolerance in transgenic Samsun NN tobacco (Nicotiana tabacum cv. Samsun NN). This was supported by heightened superoxide dismutase and peroxidase activities, increased levels of soluble protein and soluble sugars, and decreased malondialdehyde content compared to the wild type under cold stress. This study establishes a basis for the functional characterization of the bZIP gene family in tetraploid potato and serves as a theoretical reference for understanding the mechanisms that govern cold tolerance in this species.