Integrated metabolomics and proteomics analysis of anthocyanin biosynthesis regulations in passion fruit (Passiflora edulis) pericarp

Anthocyanin is the primary color-developing component in the pericarp of the passion fruit. Although the pericarp of the passion fruit is anticipated to be a significant source of anthocyanin, however, information regarding anthocyanin biosynthesis in the passion fruit pericarp remains unexplored. Based on metabolomics analysis, a total of five anthocyanins were identified in the purple-skinned passion fruit pericarp, among which three anthocyanins, petunidin-3-O-arabinoside, geranylgeranyl-3,5-O-diglucoside, and petunidin-3-O-rutinoside, play key roles in the coloration of the passion fruit pericarp. Based on proteomics analysis, a total of nine differential proteins are involved in the flavonoid metabolic process, which involves the following chalcone isomerase, flavonol synthase and anthocyanin synthasein. These proteins play important regulatory roles in anthocyanin biosynthesis and are the key regulators in anthocyanin accumulation. qRT-PCR was used to identify nine structural genes (PePAL2, PePAL4, PeC4H1, Pe4CL5, Pe4CL6, Pe4CL7, PeCHS2, PeCHS3 and PeUFGT2) playing key regulatory roles in anthocyanin synthesis in purple passion fruit pericarp. This study is expected to lay a foundation for the subsequent exploration of the regulatory mechanism of anthocyanin biosynthesis and the functional identification of related genes in passion fruit pericarp, and also to provide data support for the in-depth utilization of passion fruit resources.