Stage-specific regulation of steroidal glycoalkaloids in potato tuber peels under continuous light

Abstract

Accumulation of steroidal glycoalkaloids (SGAs) drives postharvest potato tuber greening and poses food-safety risks, yet the temporal dynamics and regulatory basis of light induction remain unclear. We compared a storage-tolerant cultivar (XS) and a storage-sensitive cultivar (JZ). Under continuous light for 0, 2, 10, and 30 d, we quantified α-solanine and α-chaconine and performed integrated metabolomic and transcriptomic analyses in JZ. SGAs increased more sharply in JZ than in XS. Metabolomics detected 616 differentially accumulated metabolites: steroid-related metabolites (diosgenin) rose rapidly at 2 d, whereas phenolic acids, flavonoids, and SGAs accumulated at 30 d. Transcriptome profiling indicated early activation of sterol/cholesterol biosynthesis and late enhancement of phenylpropanoid and phytosterol pathways. WGCNA identified candidate genes including CYP72A54, MYB185, HY5, and PIF3. We propose an “early steroid remodeling–late co-amplification of phenolics and SGAs” model, providing evidence for postharvest light-exclusion management and low-SGA breeding, and supporting risk assessment during storage and transport.