Insights into the Distinct Anthocyanin Metabolism and Transcriptomes in the Mature Pericarp of Ilex verticillata 'Winter Red' and 'Winter Gold'
Ilex verticillata is a native North American plant. The color of its fruit is not only an important manifestation of ornamental value but may also be closely related to its ecological adaptability and physiological function. This study aimed to explore the molecular mechanism underlying fruit color formation in I. verticillata. Transcriptome sequencing and anthocyanin metabolome analysis were conducted on the fruits of 'Winter Red' and 'Winter gold'. The results showed that there were significant differences in the brightness, redness, and yellowness values between the two varieties. A total of 2781 differentially expressed genes (DEGs) were identified, which were significantly enriched in the biosynthesis of secondary metabolites and metabolic pathways. Additionally, 21 differentially expressed anthocyanin metabolites were detected, and Pelargonidin-3-O-arabinoside was likely the key substance determining the color difference. The structural genes IvCHS and IvCHI were highly expressed in 'Winter Red', potentially leading to anthocyanin accumulation. A total of 203 transcription factors were annotated, including 14 MYB related families, among which transcription factors related to anthocyanin accumulation regulation may exist. This study provides important theoretical support for the breeding, cultivation, and application of I. verticillata, and also enriches our understanding of the mechanisms underlying the formation of plant fruit color.