Transcriptome and Metabolome reveal AsA regulatory network between metabolites and genes after fruit shading by bagging in kiwifruit (Actinidia eriantha)

Fruit bagging is an effective way of producing pollution-free fruit. However, the micro-environment provided by bagging for fruits could reduce the internal quality for most fruits in various degree. As a novel berry fruit, kiwifruit (Actinidia eriantha) has great potential for development. We found a change in fruit quality after fruit shading by bagging (FSB). In order to explore the regulatory mechanism of FSB on fruit quality, we used off-target metabolomics and transcriptomics to identify differential metabolites and differential genes, and focused on the molecular mechanism of the decrease in AsA content. We found that the contents of soluble solids (SSC), soluble sugar (SS), ascorbic acid (AsA), chlorophyll and carotenoid in the FSB fruit were significantly reduced. Through the non-targeted metabolome, a total of 160 metabolites showed significant differences in fruit tissue. There were 3,200 differentially expressed genes (DEGs) between FSB and control by RNA-Seq and enriched in 118 KEGG metabolic pathways. The decrease of AsA content after FSB was mainly due to the decrease of DHAR gene, MDHAR gene, APX gene and the increase of MDHA metabolite during the AsA-GSH cycle process. The decrease of GalUR gene in d-galacturonic acid pathway and the decrease of GulLO gene and Myo-inositol metabolite in Myo-inositol pathway were the secondary reasons for the decrease of AsA content. This study would provide novel insights into the effects of FSB on changes in the intrinsic and appearance quality of A. eriantha fruit.