Combined metabolomic transcriptomic analysis reveals the role of flavonoid pathway in white rot resistance of Vitis davidii Foex. grapes

Grape white rot is a devastating disease caused by Coniella diplodiella (Speg.) Sacc. The wild Chinese grape variety Vitis davidii Foex. 0941 (V. davidii) exhibits strong resistance to this disease, which is crucial for the utilization of wild resources in developing new disease-resistant cultivars. However, the underlying mechanism of V. davidii's resistance remains unclear. In this study, we collected berries from the disease-resistant V. davidii and the disease-susceptible Vitis vinifera 'Manicure Finger' (V. vinifera) after inoculation with the grape white rot fungus. Through transcriptome and metabolome analyses, we observed that in the berries of V. davidii, metabolites associated with flavonoid metabolism, including naringenin, tricetin, eriodictyol, luteolin, dihydrokaempferol, myricetin, and syringetin, are significantly enriched compared to those in V. vinifera. Moreover, core genes involved in flavonoid metabolism (F3′5′H, F3′H, PAL, FLS) are expressed at higher levels in V. davidii. We have also identified several candidate genes associated with flavonoids, including flavonoid 3′,5′-methyltransferase-like, cellulose synthase-like protein E6, and flavonoid 3′,5′-hydroxylase 2, which are highly expressed in V. davidii. This finding was further validated by qRT-PCR analysis, which also revealed higher expression levels of these genes in the resistant variety. Collectively, these results suggest that flavonoid compounds may play a key role in the resistance of V. davidii to Coniella diplodiella.