Metabolomic analysis of seed coat and peeled seeds of polygonatum cyrtonema in sand storage

The ending of seed dormancy by sand storage involves complex interactions in cells. To assess the effect of sand storage on dormancy breaking in seeds of Polygonatum cyrtonema Hua, the seed germination rate and metabolites change were monitored in seed coat and peeled seeds. The germination rate of P. cyrtonema seeds was increased after 60 d of storage at 4 degrees C or room temperature -5 to 15 degrees C. Metabolomics analysis showed that there were 85 and 74 metabolites in seed coat and peeled seeds, respectively. The dynamic changes in metabolites and in metabolic pathways during sand storage were analyzed by the principal component analysis (PCA) and orthogonal partial least squares -discriminant analysis (OPLS- DA) models. Metabolomics analysis showed that sand storage had different effects on the seed coat and peeled seeds. The tricarboxylic acid (TCA) cycle, amino acid metabolism, and gluconeogenesis of the peeled seeds were active in sand storage for 30 d and 60 d, which provided energy for seed germination. Myo-inositol and gamma-aminobutyric acid (GABA), molecules related to seed germination, were also affected in the sand storage process. These results provide a comprehensive analysis of the metabolic changes for exploring the seed dormancy mechanism of P. cyrtonema.