Transcriptome analysis of branches reveals candidate genes involved in anthocyanin biosynthesis of 'Red Bartlett' pear (Pyrus communis L.)

The color of the peel is the most direct reflection of fruit quality, and is also an important factor in attracting consumers. The `Red Bartlett' pear (Pyrus communis L.) is a red bud sport mutant variety of `Bartlett' pear. It was found that the anthocyanin content in branches and pericarps of `Red Bartlett' pears were significantly higher than that of `Bartlett' pears. The present study aimed to clarify the underlying mechanisms of anthocyanin accumulation in `Red Bartlett' using a transcriptome analysis. A weighted gene coexpression network analysis (WGCNA) identified 495 differentially expressed genes positively associated with anthocyanin. Additionally, 12 anthocyanin-related structural genes and 13 transcription factors, including WRKY, ERF, bHLH, ASIL2, and HSF, were identified through screening of 495 DEGs. The expression levels of one UFGT (Pbr014258.1) and one GST (Pbr012649.1) were also upregulated in the pericarps of `Red Bartlett' and `Starkrimson', more so than in `Bartlett' and `Clapps Favourite'. Overall, this study clarified that the red color mutation of `Red Bartlett' was closely linked to increased anthocyanin biosynthesis and transport. This study provided an abundance of valuable information on anthocyanin biosynthesis for future breeding of red-skinned pears.