Size-dependent diversity and accumulation of isoquinoline alkaloids in Corydalis yanhusuo tubers

Corydalis yanhusuo is a traditional analgesic herb, with alkaloids as its primary active compounds and quality markers. The quality of C. yanhusuo available in the market varies considerably and is often classified by tuber size. However, whether quality differs among tubers of different sizes, and the molecular mechanisms underlying such differences, remains unclear. Hence, we aimed to investigate the relationship between tuber size and alkaloid accumulation in C. yanhusuo using integrated metabolomic and transcriptomic analyses. Targeted metabolomics and transcriptomic analyses were conducted on C. yanhusuo tubers of three different sizes. Differential alkaloid profiles and gene expression patterns were correlated, and abscisic acid (ABA) treatment was used to assess transcription factor responses. The total alkaloid content in small tubers was higher than that in large tubers. Targeted metabolomics analysis revealed 481 alkaloids, predominantly isoquinoline alkaloids (41.58 %), most of which were more abundant in small tubers than in large ones. Combined with transcriptome data, our findings suggested that alkaloid accumulation in differently sized tubers might be related to environmental adaptation and trade-offs between tuber growth and development. Core transcription factors, including NAC, C3H, and GRAS, which are responsive to 50 μM ABA, may regulate the growth and development of C. yanhusuo. This regulation may contribute to differences in alkaloid content and morphology among tubers of varying sizes. Our study provides a reference for improved utilization of C. yanhusuo and offers scientific insights for future molecular breeding.