Metabolome and Transcriptome Analyses Reveal Mechanisms of Leaf Red Spot Formation in Peach (Prunus persica)

The peach tree (Prunus persica), which originated in China, has a long history of cultivation and holds significant economic value. However, Peach Red Leaf (PRL) disease adversely affects the growth, development, and commercial quality of peach fruits. In this study, we performed metabolomic and transcriptomic analyses, with a focus on anthocyanins, to investigate the mechanisms underlying Leaf Red Spot (LRS) formation in peach leaves. Our results revealed that compared to control samples, slight red spots and red leaf samples accumulated higher levels of anthocyanins. The most prominent anthocyanins were procyanidin, cyanidin, pelargonidin, delphinidin, and peonidin. Anthocyanin accumulation peaked annually during October and November in PRL-affected leaves. Furthermore, we identified 28 differentially expressed genes involved in anthocyanin biosynthesis, with 19 being upregulated and nine downregulated. Our findings suggest that the LRS symptoms in peach are primarily driven by the accumulation of anthocyanins. Additionally, through comparison with the peach genome and virus database, we identified the grapevine red globe virus and tomato spotted wilt virus as potential viral contributing factors to the PRL disease. These viruses exhibited a seasonal pattern of accumulation, closely linked to temperature changes, with suppression occurring during the winter months. Overall, this study shed light on the molecular and metabolic mechanisms underlying LRS symptoms in peach leaves.