Advances in Understanding Cold-Induced Sweetening in Potato Tubers

Cold-induced sweetening (CIS) in potato tubers represents a significant challenge for the potato processing industry, characterized by the accumulation of reducing sugars during cold storage that leads to undesirable browning and potential acrylamide formation during frying. This comprehensive review integrates current understanding of CIS mechanisms, from pre-harvest factors through molecular regulation to breeding strategies. Recent multi-omics studies have revealed complex regulatory networks involving transcriptional, post-transcriptional, and epigenetic modifications. Key metabolic pathways include starch degradation, primarily regulated by β-amylase (BAM) and starch phosphorylase (PHO1), sucrose biosynthesis controlled by UDP-glucose pyrophosphorylase (UGPase) and sucrose phosphate synthase (SPS), and sucrose degradation mediated by vacuolar invertase (StVInv). The discovery of VInvIn2En, a cold-responsive enhancer in StVInv's second intron, has provided new insights into transcriptional regulation. Notably, the interaction between StVInv and its inhibitor (StInvInh2), modulated by the SnRK1 complex, emerges as a central regulatory mechanism. The role of tonoplast sugar transporters (TST), particularly StTST1, has been identified as crucial in sugar compartmentalization. Environmental factors, including ethylene and hypoxia, significantly influence CIS through distinct molecular mechanisms. Breeding efforts have leveraged wild Solanum species and molecular tools, including CRISPR/Cas9-mediated gene editing, to develop CIS-resistant varieties. Despite these advances, challenges remain in understanding plastidial transport mechanisms, regulatory networks, and translating molecular insights into practical breeding applications. Future directions emphasize the need for integrated approaches combining genetic improvement, optimized storage conditions, and enhanced understanding of regulatory mechanisms to develop sustainable solutions for the potato industry.