Golden biomass: unlocking the potential of neglected potato (Solanum tuberosum L.) side-streams as sources of bioactive compounds

Background Potato flowers and berries are largely unused agricultural side-streams that may provide bioactive compounds for pharmaceutical and plant protection applications in a circular bioeconomy. This study evaluated their potential as sources of secondary metabolites and assessed whether premature harvesting affects final tuber yield. Methods Field trials with two potato cultivars were combined with targeted HPLC-MS/MS analysis, untargeted metabolomics, and RNA-Seq analysis of flowers and developing berries. Results Berries produced substantially more biomass than flowers, whereas flowers generally contained higher concentrations of total glycoalkaloids (calculated as the sum of a-solanine and a-chaconine). This reached 393.95 mg/100 g FW in ‘Quarta’ flowers compared to 70.92 mg/100 g FW in berries, with the concentration of a-chaconine up to 3.33-fold higher than that of a-solanine. Untargeted metabolomics identified glycoalkaloids, phenolic compounds, and other secondary metabolites, with peak intensities of rutin and some others declining from ~1Å~10 9 to ~1Å~10 5 during berry development. Transcriptomic analysis showed that tissue and developmental stage had a substantially greater influence on gene expression patterns than cultivar. Genes associated with phenylpropanoid, terpenoid and steroid-related pathways were differentially expressed, with overall stronger upregulation in flowers than in small and big berries. Premature flower harvest did not reduce tuber yield, whereas berry harvest reduced yield for one cultivar in one field experiment. Conclusion Overall, flowers and berries harvested as side streams in the potato production can be a good source for glycoalkaloids and possibly further metabolites of use for pharmaceutical and plant protection applications. Flowers appear particularly suitable for recovering high-concentration bioactive compounds, whereas berries offer advantages in biomass availability, harvesting, and storage.