Potato (Solanum tuberosum L.) is a major food crop cultivated in more than 150 countries worldwide, consistently ranking within the top five in global production (Camire et al., 2009; Zaheer and Akhtar, 2016). According to the FAO, global potato production reached approximately 383 million tons in 2023, with China contributing approximately 93.5 million tons, or nearly 24% of the total (Callıskan et al., 2022; Potato Pro, 2025). China has long maintained a leading position in potato cultivation area, production, and processing capacity, with its output representing more than 20% of the global total (Hu et al., 2025). Owing to its high yield potential, production efficiency, and versatility of use, the potato plays an important role in global food security, agricultural processing, and industry. Despite the large planting area, potato yield is below potential, which is further exacerbated under adverse environmental conditions such as extreme temperatures, diseases, and water stress. Among these constraints, low-temperature stress, including chilling and frost injury, represents one of the most critical abiotic factors compromising the stability of potato production.

Low-temperature stress, categorized as freezing stress (<0 °C) and chilling stress (0–15 °C), greatly limits plant growth, development, and geographic distribution (Guo et al., 2018; Ding and Yang, 2022). Freezing stress often results in ice crystal formation within cells, leading to structural disruption, severe membrane damage, and, ultimately, plant death. In contrast, chilling stress primarily alters the lipid composition of cellular membranes, which impairs membrane protein function and affects key metabolic processes such as photosynthesis and respiration, along with enzyme activity (Zhao et al., 2020; Aslam et al., 2022). At the developmental level, low temperatures can delay bud break, induce chlorosis in seedlings, reduce photosynthetic efficiency, and impair reproductive development, all contributing to yield loss (Li et al., 2022; Hou et al., 2022). Physiologically, low temperatures induce a phase transition of membranes from a liquid-crystalline to a gel state, thus reducing membrane fluidity and leading to lipid peroxidation, which is reflected by elevated malondialdehyde (MDA) accumulation (Wang et al., 2021). The concurrent excessive accumulation of reactive oxygen species (ROS) disrupts cellular macromolecules and compromises cellular integrity. Plants rely on components of the enzymatic antioxidant defense system, including superoxide dismutase (SOD) and peroxidase (POD), as well as non-enzymatic antioxidants such as ascorbic acid and glutathione, to maintain redox homeostasis under stress (Noctor et al., 2014; Wang et al., 2018; Mittler et al., 2022). At the molecular level, the ICE1–CBF–COR transcriptional cascade represents the core cold-response pathway. ICE1 activates CBF genes, which subsequently regulate a wide range of cold-inducible genes, thereby enhancing freezing and chilling tolerance (Shi et al., 2018; Verslues et al., 2023). Moreover, the abscisic acid (ABA) signaling pathway plays a critical role in stomatal regulation and cold stress adaptation. The regulatory module composed of PYR/PYL/RCAR receptors, protein phosphatase 2C (PP2C), and SNF1-related protein kinase 2 (SnRK2) has been shown to interact with the CBF–COR network, leading to the strengthening of the low-temperature response (Dou et al., 2021; Zhang et al., 2021; Wi et al., 2022). Collectively, these observations indicate that low-temperature stress impairs plant performance through membrane destabilization, ROS accumulation, and signaling pathway alterations, ultimately compromising growth and yield.

Fatty acids and their derivatives are essential components of plant cells, serving both as energy reserves and critical constituents of membrane structure and function. Fatty acid desaturases (FADs) catalyze the formation of double bonds in fatty acid chains, generating unsaturated fatty acids, and are central to the maintenance of membrane stability, the regulation of metabolism and hormone signaling, and mediating plant responses to both biotic and abiotic stresses (Dar et al., 2017; Laureano et al., 2021). The FAD gene family has been systematically characterized in several crops, including soybean (Glycine max), rice (Oryza sativa), peanut (Arachis hypogaea), tomato (Solanum lycopersicum), and cotton (Gossypium hirsutum), and FAD family members were found to be closely associated with stress tolerance in plants. The overexpression of soybean GmFAD3A and poplar PtFAD2 significantly enhanced cold tolerance, whereas the expression of antisense AtFAD7 of Arabidopsis reduced tolerance to drought and salt stresses (Zhou et al., 2010; Román et al., 2012). Based on subcellular localization and functional diversity, plant FAD proteins can be divided into soluble and membrane-bound types, with the latter further categorized into subfamilies such as FAD2/FAD6 (ω-6 desaturases) and FAD3/FAD7/FAD8 (ω-3 desaturases) (Cheng et al., 2022). These enzymes regulate the biosynthesis of polyunsaturated fatty acids, including linoleic acid (C18:2) and linolenic acid (C18:3), thereby modulating membrane unsaturation and phase transition temperature and consequently enhancing plant adaptation to low-temperature environments (Upchurch, 2008). Among them, FAD8, a chloroplast-localized ω-3 desaturase that is specifically induced by cold, has been shown to play a pivotal role in cold stress responses across multiple species. The overexpression of AtFAD8 or OsFAD8 increases C16:3 and C18:3 levels in transgenic plants and enhances their cold tolerance, whereas silencing FAD8 reduces trienoic acid content and results in greater sensitivity to low temperatures (Román et al., 2015; Soria-García et al., 2019). Collectively, the FAD gene family is integral to membrane lipid remodeling and low-temperature adaptation, with FAD8 acting as a key regulator in this process. However, although potato is particularly sensitive to chilling compared with many other crops, the contribution of FAD-mediated pathways to potato cold adaptation has not been systematically investigated. Furthermore, the molecular mechanisms underlying the responses of this important crop to abiotic stresses, especially cold stress, remain largely unclear.

In this study, we undertook a genome-wide search for FAD gene family members in potato. We characterized their chromosomal distribution, gene structure, conserved motifs, and cis-regulatory elements, and analyzed their evolutionary features and potential biological functions. Furthermore, we investigated the expression profiles of these genes under low-temperature stress to identify their roles in cold stress response. The findings of this study provide novel insights into the regulatory network of FAD genes in potato cold adaptation and offer theoretical support and valuable genetic resources for the breeding of cold-tolerant potato varieties.

Fatty acid desaturases comprise a family of enzymes that catalyze the formation of double bonds in fatty acid chains, thereby regulating membrane fluidity, lipid metabolism, and stress adaptability in plants (Jin et al., 2024). Their roles in maintaining cellular homeostasis under abiotic stresses, particularly cold, have been extensively documented in multiple species (Li et al., 2024; Lu et al., 2025). In this study, we systematically characterized the StFAD gene family in potato, offering insights into their structural features, evolutionary patterns, and potential functions in cold stress adaptation.

Our genome-wide survey revealed that the potato FAD gene family comprises 47 members, exhibiting an uneven chromosomal distribution with notable clusters on chromosomes 6 and 12. This pattern suggests that tandem and segmental duplications may have driven their local expansion. Comparable expansions have been documented in other crops. In soybean, 30 GmFAD genes have been identified and classified into seven subfamilies, with segmental duplication serving as the primary driver of expansion (Li et al., 2025). In tomato, 26 SlFAD genes were unevenly mapped across 10 chromosomes, forming six clades, and their promoter elements were enriched for hormone- and stress-responsive motifs (Xi et al., 2023). These lineage-specific expansions across species highlight a general evolutionary trend in which duplication events increase both family size and regulatory complexity. The expansion observed in S. tuberosum may reflect adaptive genome evolution in response to ecological and physiological demands.

Comparative structure–function analysis classified the 47 StFAD genes into six canonical subfamilies, FAB2, FAD2, FAD3/7/8, FAD4, FAD6, and ADS/SLD/DES, consistent with observations in model plants. While core motifs and domain architectures were largely conserved within subfamilies, subgroup-specific differences in motif retention and exon–intron structures were evident, indicative of potential functional specialization. Similar structural conservation combined with divergence has been reported in rice, where 20 OsFAD genes were identified and grouped into six subfamilies. Tandem and segmental duplications underpinned their expansion while domain conservation preserved the defining characteristics of each subfamily (Chen et al., 2019). In cucumber (Cucumis sativus), 23 CsFAD genes were identified, all retaining the characteristic histidine motifs (HXXXH, HXXHH, HXXHH) responsible for desaturase activity, and many membrane-bound members contained organelle-targeting signals (Dong et al., 2016). Similarly, in upland cotton (G. hirsutum), 39 GhFAD genes were identified, with phylogenetic clustering revealing four conserved subfamilies in which gene structures were strongly preserved. Segmental duplication again appeared to be the predominant process underlying their expansion (Feng et al., 2017). These observations indicate that FAD family architecture is broadly conserved across species, with lineage-specific duplications and motif variations contributing to functional divergence. Our analysis of StFAD genes fits this paradigm, with conservation supporting essential roles in fatty acid metabolism, and divergence contributing to regulatory and functional diversity.

Cold-responsiveness is a common feature of plant FAD genes, and our results confirmed that several StFAD members in potato exhibit transcriptional activation under cold conditions. Among them, StFAD7 displayed the most pronounced and sustained induction, with transcript levels peaking at 12–24 h of 4°C treatment. This expression pattern coincided temporally with a transient rise and subsequent attenuation of malondialdehyde (MDA) content, as well as a continuous increase in superoxide dismutase (SOD) and catalase (CAT) activities in tubers. The synchronous upregulation of StFAD7 and enhancement of antioxidant enzyme activity suggest that StFAD7 induction may be functionally linked to the mitigation of oxidative stress and maintenance of membrane stability during chilling. Similar patterns have been reported in other species, where cold-induced desaturases, contribute to increased unsaturated fatty acid levels and improved tolerance to low temperatures. For instance, the overexpression of GmFAD3A in rice significantly improved cold tolerance at 15°C, enhancing seed germination, survival, and antioxidant enzyme activity, while concomitantly mitigating oxidative damage (Wang et al., 2019). In A. thaliana, ACYL-LIPID DESATURASE 2 (ADS2) is indispensable for cold acclimation. ads2 mutants show increased levels of saturated fatty acids and exhibit dwarfism, sterility, and severe cold sensitivity, while ADS2 expression is rapidly induced during chilling (Chen and Thelen, 2013). These cross-species parallels highlight the central role played by desaturases, particularly ω-3 types, in mediating cold adaptation.

The regulatory architecture of FAD genes further emphasizes their multifaceted roles in environmental adaptation. Our promoter analysis revealed that many StFAD genes harbor cis-elements that are responsive not only to cold but also to hormones (e.g., ABRE, ERE) and light (e.g., G-box, Box4). Promoter–reporter studies in A. thaliana demonstrated that AtFAD7 and AtFAD8 are differentially regulated via combinations of WRKY and MYB binding sites, along with ABA-responsive elements (Sahoo et al., 2023). Stress-responsive elements such as ABRE and DRE/CRT are well established as key regulators of gene activation under cold, drought, and salinity (Luján et al., 2021). In olive (Olea europaea), cold treatment during fruit development markedly upregulated FAD7 and FAD2.2 expression, which correlated with increases in unsaturated lipid content. This suggests that cis-element-mediated regulation may be functionally linked to membrane adaptation (Yamaguchi-Shinozaki and Shinozaki, 1994). Consistent with these findings, our analysis revealed that StFAD7 possesses a promoter enriched in cold- and hormone-responsive cis-elements such as LTR, ARE, and ABRE, implying transcriptional regulation through multiple signaling pathways. Experimentally, StFAD7 was confirmed to localize to the plasma membrane through GFP-fusion transient expression in Nicotiana benthamiana epidermal cells, where fluorescence signals overlapped with the plasma membrane marker PIP2A–mCherry. This localization agrees with bioinformatic predictions and is biologically meaningful, as the plasma membrane is the primary site of cold-induced damage. Membrane-bound ω-3 desaturases such as StFAD7 may modulate lipid desaturation and preserve bilayer fluidity, thereby reducing mechanical rigidity and oxidative damage under chilling stress (Matteucci et al., 2011; Liu et al., 2020). Similar mechanisms have also been observed in other crops such as Arabidopsis, rice, and soybean, where ω-3 desaturases play conserved roles in maintaining membrane fluidity and enhancing cold stress tolerance, further supporting the conclusions of this study. Together, these molecular and cellular findings align with the observed physiological responses, reinforcing the hypothesis that StFAD7 might contribute to cold adaptation in potato by maintaining membrane stability and facilitating lipid remodeling under low-temperature conditions. The current study integrates transcriptional induction, physiological responses, and membrane-associated localization to support the functional relevance of StFAD7, direct measurement of fatty acid desaturation or membrane lipid composition would provide additional biochemical confirmation. Lipidomic profiling will be incorporated in future work to determine whether cold-induced StFAD7 activation leads to measurable changes in unsaturated fatty acid levels.

The cold-response validation in this study was performed using the commercial cultivar ‘Atlantic’ under a standard chilling treatment (4°C). ‘Atlantic’ was selected because of its agricultural relevance and its clear, reproducible sensitivity to low temperature, which facilitates correlation between transcriptional and physiological responses. Future research will systematically evaluate multiple potato genotypes and extended time courses to refine the functional characterization of StFAD7. Taken together, this study establishes an integrative framework connecting genome-wide identification, functional prediction, physiological validation, and subcellular localization to elucidate the potential role of StFAD7 in potato cold adaptation. Starting from a comprehensive survey of 47 StFAD genes, we classified them into six subfamilies and revealed conserved ω-3 desaturases enriched in cold- and hormone-responsive cis-elements. Transcriptomic and qRT–PCR analyses further identified StFAD7 as the most strongly and persistently induced member under 4°C treatment, coinciding with the attenuation of MDA accumulation and the enhancement of SOD and CAT activities, thereby linking gene expression to physiological adaptation. Subcellular localization demonstrated that StFAD7 resides at the plasma membrane, the first cellular interface challenged by low temperature, consistent with its putative role in regulating membrane lipid desaturation and maintaining ROS homeostasis. Together, these multi-level findings outline a coherent progression from genome-scale screening to candidate gene validation, supporting the hypothesis that StFAD7 contributes to lipid-based defense and redox stabilization under cold stress. Future work integrating transgenic overexpression, CRISPR/Cas9-mediated knockout, and lipidomic profiling will be essential to confirm its precise function and facilitate the breeding of cold-resilient potato cultivars.

This study provides a comprehensive overview of the FAD gene family in Solanum tuberosum, revealing its structural diversity and potential roles in cold stress adaptation. A total of 47 StFAD genes were identified and classified into six subfamilies, exhibiting conserved domain architectures but distinct exon–intron patterns, suggesting both evolutionary conservation and functional divergence. Promoter analysis highlighted the enrichment of cold, hormone, and light-responsive cis-elements, indicating complex transcriptional regulation. Expression profiling and qRT–PCR validation demonstrated that StFAD7 is markedly induced by low-temperature treatment (4°C, 12–24 h), coinciding with reduced lipid peroxidation and enhanced antioxidant enzyme activities. Subcellular localization confirmed that StFAD7 is a membrane-associated desaturase, supporting its role in maintaining lipid fluidity and redox balance during chilling stress.