Potato tubers undergo greening and accumulate steroidal glycoalkaloids (SGAs) upon light exposure, posing potential food safety risks. In this study, six potato cultivars (“Favorita”, “Lucinda”, “Jizhangshu 12”, “Longshu 10”, “Qingshu 9”, and “Purple Potato”) were subjected to six light treatments (dark, UVA, blue, green, red, and white), and peel color, pigment content, SGAs, and the expression of genes related to light signaling, chlorophyll biosynthesis, and SGA biosynthesis was evaluated. Under green light, the contents of α-solanine and α-chaconine were 76.22 and 171.84 mg/kg fresh weight (FW), respectively; by contrast, their levels under blue and white light were approximately 60% higher. These effects may be mediated by the upregulation of HY5 and COP1 expression, which in turn could regulate the biosynthesis of chlorophyll-related genes (CHID, CHLI1) and SGA-related genes (HMGR, SGT1). Yellow-skinned cultivars exhibited pronounced light sensitivity (chlorophyll 18.47–18.52 mg/kg FW; SGAs up to 290.41 mg/kg FW), whereas red- and purple-skinned cultivars delayed greening through anthocyanin-mediated light attenuation. Collectively, these findings provide a framework for postharvest management and breeding, suggesting that reducing blue light while enhancing green light in spectral illumination, together with the development of anthocyanin-enriched cultivars, may serve as effective strategies to extend shelf life, mitigate food safety risks, and reduce postharvest losses.

Enzymatic browning markedly reduces the processing quality and economic value of potatoes. This study evaluated the effects of copper sulfate (CuSO₄) on potato growth, yield, and enzymatic browning. Quantitative analysis of browning-related enzymes, organic acids, free amino acids, and the browning index (BI) was conducted using high-performance liquid chromatography and non-contact colorimetric technology. Moderate Cu²⁺ (0.078–0.157 mmol·L⁻¹) supply enhanced photosynthetic capacity, biomass, and starch accumulation, whereas excessive Cu induced oxidative stress, increased PPO activity, phenolic accumulation, and BI. Metabolic profiling revealed that Cu²⁺ activates PPO via its copper-binding sites and reprograms amino acid and organic acid metabolism—upregulating arginine and proline while downregulating isoleucine, leucine, phenylalanine, lysine, citrate, and chlorogenic acid, all strongly correlated with BI. These findings highlight the dual role of copper in yield formation and enzymatic browning, introducing metabolic reprogramming as a potential mechanism for optimizing Cu fertilization to balance productivity and postharvest quality.

RING-zf E3 ligases play key roles in plant development and light signaling, but their genome-wide characterization and light-responsive functions in potatoes remain largely unexplored. In this study, we identified 291 StRING-zf genes containing complete RING domains in the potato genome and classified them into four major RING domain types, with RING-H2 being the predominant and structurally conserved group. Evolutionary analyses indicated that gene duplication contributed to the expansion of the StRING-zf genes, while promoter analysis revealed abundant cis-regulatory elements associated with light, hormones, and abiotic stress responses. Transcriptome analysis of the terminal leaflets of the third leaves of potato seedlings under different light qualities, combined with qRT-PCR validation, revealed diverse and gene-specific expression patterns among StRING-zf genes. Five candidate genes (Soltu.DM.01G022260.1, Soltu.DM.04G001050.1, Soltu.DM.10G023720.1, Soltu.DM.11G009040.1, and Soltu.DM.11G017440.1) exhibited distinct light-quality-dependent expression responses. These expression patterns provide preliminary evidence for their potential involvement in light-responsive regulatory processes and ubiquitin-mediated protein modification. Overall, this study provides a comprehensive genomic and transcriptomic resource for elucidating the evolutionary characteristics and potential functions of the StRING-zf genes and identifies candidate genes for further functional validation of light-responsive mechanisms in potatoes.