Metabolomic and Transcriptomic Analysis Reveals the Mechanisms Underlying the Difference in Anthocyanin Accumulation in Apple Fruits at Different Altitudes

The red color of apple peel is an important phenotypic and economic trait mainly attributed to anthocyanin accumulation. Apples show a deeper at higher altitudes than lower ones; however, the molecular regulatory network underlying variation along altitudinal gradients has not been investigated. In this study, effects environmental conditions associated with low (124 m) high (1901 on were assessed through physiological, metabolomic, transcriptomic, qRT-PCR analyses in Huashuo its sister line, Huarui apple. content cyanidin-3-O-galactoside, cyanidin-3-O-arabinoside, cyanidin-3-O-xyloside was abundant high-altitude environment may contribute color. Transcript levels structural genes synthesis pathway, especially MdCHI, MdCHS, MdANS, MdDFR, significantly altitude altitude. Based protein interaction prediction correlation analyses, four transcription factors (MDP0000127691, MDP0000284922, MDP0000758053, MDP0000074681) could interact synthesis-related proteins, showing Therefore, abovementioned predicted account for differences between altitudes. These results provide genetic resources theoretical basis color-oriented fruit improvement.