GC-MS Non-Target Metabolomics-Based Analysis of the Volatile Aroma in Cerasus humilis After Grafting with Different Rootstocks

C. humilis is a small shrub belonging to the Rosaceae family, and grafting is one of the main ways for propagation. However, the influence of different rootstocks on volatile aroma is still unclear. In this study, an untargeted metabolomics approach based on gas chromatography–mass spectrometry (GC-MS) was utilized to analyze the volatile differential metabolites between the rootstock–scion combinations and self-rooted seedlings. Furthermore, metabolic pathway enrichment analysis was performed using the Kyoto Encyclopedia of Genes and Genomes (KEGG) database. In total, 191,162 and 150 volatile differential metabolites were identified in different rootstock–scion combinations. The rootstock–scion combinations of ZG/MYT and ZG/BT could improve the volatile aroma in the fruit of C. humilis and made significant contributions to the rose and fruity flavors. KEGG pathway analysis indicated that the differential metabolites were mainly enriched in the butanoate metabolism and glycolysis/gluconeogenesis pathways, showing an increasing trend. Prunus tomentosa and Amygdalus communis can serve as preferred rootstocks for enhancing the aroma quality of C. humilis fruits. These results provide new insight into rootstock-based propagation and breeding and also offer some guidance for graft-based fruit production.