Comprehensive Transcriptomics, Hormone Metabolomics, and Physiological Analysis Reveal the Mechanism of Exogenous GA4+7 Breaking the Seed Dormancy in Polygonatum cyrtonema Hua

Polygonatum cyrtonema Hua (P. cyrtonema) is a medicinal plant with high pharmaceutical value. Due to morphological and physiological dormancy mechanisms in P. cyrtonema seeds, natural germination rates remain exceptionally low. This biological constraint necessitates the development of protocols to shorten germination timelines and improve germination efficiency, which are critical requirements for advancing P. cyrtonema breeding programs. In this study, exogenous gibberellin A4 + A7 (GA4+7) was applied to break dormancy in P. cyrtonema seeds. Transcriptomic, hormone metabolomic, and physiological analyses were then employed to investigate the underlying mechanisms. Germination tests revealed that 50 mg&middot:L&minus:1 GA4+7 was the optimal concentration to break dormancy in P. cyrtonema seeds. Transcriptome analysis indicated that exogenous GA4+7 induced the expression of genes involved in GA and ABA biosynthesis and signaling. A total of 19 differential hormone metabolites were identified through hormone metabolomics, with significantly increased levels of active GA1 and GA4, but decreased levels of ABA content. These findings were consistent with the up-regulation of transcript levels of GA biosynthesis-related genes and the down-regulation of ABA biosynthesis-related genes, which resulted in an increase in active GA/ABA ratio. At the same time, it was found that exogenous GA4+7 treatment induced sucrose and starch metabolism and pectin catabolic pathways. We measured the relevant physiological indicators and found that the content of soluble sugar and &alpha:-amylase activity increased, but the pectin content decreased. These findings establish a theoretical foundation for applying GA4+7 in the standardized production of P. cyrtonema, particularly for accelerating breeding cycles in medicinal germplasm development.