Integrated metabolome and transcriptome analysis reveals the mechanism related to the formation of peelability in Actinidia eriantha

Actinidia eriantha is prone to peeling at the soft ripening stage, which is a unique characteristic that distinguishes it from other Actinidia species. However, the mechanism underlying the formation of peelability in A. eriantha is still not very clear. In this study, two A. eriantha varieties with contrasting peeling behavior were used as materials and the peel cell wall metabolism-related substances and enzyme activities were detected during fruit development. The peel cell structures were observed and the transcriptome and metabolome analysis were performed. The results indicated that the firmness and toughness of the fruit peel affect the peelability of A. eriantha. The increased activities of beta-galactosidase, pectinase, and cellulase promoted the degradation of lignin, cellulose, hemicellulose, and total pectin, and ultimately affected the peelability. The anatomical structure showed that the staining intensity on the peel of the two varieties did not change much at different stages. The differential metabolites were mainly flavonoids, lipids, and phenolic acids. Eight genes that may be related to fruit peeling traits of A. eriantha were identified, three of which (AeGAE6, AebHLH35-like, and AeBGAL5) may be the main genes affecting the peelability of A. eriantha. These candidate genes may affect the peelability of A. eriantha by influencing the metabolism of cell wall components such as galactose, mannose, arabinose, and glucuronic acid.