Analysis of coloration characteristics of Tunisian soft-seed pomegranate arils based on transcriptome and metabolome

In this study, combining metabolome and transcriptome, color related attributes and phenolic compositions of Tunisian pomegranate arils from 7 Chinese regions at same developing stage were studied. The total anthocyanin (TAC), flavonoids, and percent polymeric color (PPC) were ranged at 8.93-28.41 mg/100 g arils, 37.55-69.72 mg/100 g arils, and 3.38-21.96%, respectively. In total, 51 phenolic compounds were characterized, most of which were markedly higher in reddish-purple pomegranate arils than those levels in reddish pomegranate arils. In contrast, the accumulation of tannins was significantly higher in reddish pomegranate arils. Among the 49 differentially expressed genes, 8 and 5 genes were matched to β-glucosidase and peroxidase, respectively. Correlation analysis showed that PPC was negatively correlated with 10 phenolic metabolites and TAC, positively correlated with L*, polymeric color, and 1 gene (|r| > 0.7, p < 0.01). Our results provide new insights for understanding the difference in coloration of pomegranate arils.