Transcriptome Analysis Reveals Roles of Sucrose in Anthocyanin Accumulation in 'Kuerle Xiangli' (Pyrus sinkiangensis Yu)

Pear (Pyrus L.) is one of the most important temperate fruit crops worldwide, with considerable economic value and significant health benefits. Red-skinned pears have an attractive appearance and relatively high anthocyanin accumulation, and are especially favored by customers. Abnormal weather conditions usually reduce the coloration of red pears. The application of exogenous sucrose obviously promotes anthocyanins accumulation in 'Kuerle Xiangli' (Pyrus sinkiangensis Yu); however, the underlying molecular mechanism of sucrose-mediated fruit coloration remains largely unknown. In this study, comprehensive transcriptome analysis was performed to identify the essential regulators and pathways associated with anthocyanin accumulation. The differentially expressed genes enriched in Gene Ontology and the Kyoto Encyclopedia of Genes and Genomes items were analyzed. The transcript levels of some anthocyanin biosynthetic regulatory genes and structural genes were significantly induced by sucrose treatment. Sucrose application also stimulated the expression of some sugar transporter genes. Further RT-qPCR analysis confirmed the induction of anthocyanin biosynthetic genes. Taken together, the results revealed that sucrose promotes pear coloration most likely by regulating sugar metabolism and anthocyanin biosynthesis, and this study provides a comprehensive understanding of the complex molecular mechanisms underlying the coloration of red-skinned pear.