Flavonoid Biosynthetic Pathway Affects the Ripening of Hawthorn Fruits

As a plant that integrates medicinal and edible properties, hawthorn (Crataegus pinnatifida Bunge) boasts rich nutrients. However, the concentrated maturity period and scarcity of early-maturing varieties significantly hinder the development of the hawthorn industry. To elucidate the mechanisms underlying early ripening in hawthorn, we conducted a transcriptome analysis on the ‘Dajinxing’ hawthorn variety and its early-ripening bud mutant ‘Jinhong No. 1’ across three developmental stages. Our results revealed a total of 8744 differentially expressed genes (DEGs) between ‘Jinhong No. 1’ and ‘Dajinxing’. The integration of Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses highlighted a pronounced enrichment in the flavonoid biosynthesis pathway during fruit maturation. Protein-protein interaction (PPI) network analysis at 30 days post-anthesis demonstrated a limited number of DEGs, with only two gene products participating in interactions. In the subsequent developmental stage, protein-network interaction network were detected to be more complex. Transcription factor analysis identified bHLH, NAC, and MYB_related families as the most abundant, suggesting their potential roles in hawthorn fruit ripening. Heatmap analysis of DEGs involved in flavonoid biosynthesis revealed substantial differences between the mutant and parental hawthorn fruits during the color-changing stage, with widespread upregulation of DEGs, indicating their pivotal roles in regulating hawthorn fruit development.