Omic analysis of anthocyanin synthesis in wine grape leaves under low-temperature

• Low-temperature promotes the accumulation of anthocyanins in grape leaves by up-regulating the expression of structural genes that induce anthocyanin synthesis, related transcription factors and LRR-type receptor-like protein kinases. • Under the same low-temperature environment, the more anthocyanin accumulated in the leaves, the less damage they suffered. • The synthesis and accumulation of anthocyanins promoted the adaptation and resistance of grape leaves to low-temperature environmental conditions. Anthocyanins can be induced by environmental factors such as low- temperature, and play an important role in adapting to abiotic stress. In this study, the leaves of 'Cabernet Gernischt' grapes with different colors under natural low-temperature in autumn were collected and grouped into Green (Gre), Light-red (L-Red), Red (Red), and Dark-red (D-Red). Results showed that the total anthocyanin content and anthocyanin components were increased in turn from Gre to D-red. Under the same low-temperature, Gre was substantially damaged, L-Red was mildly damaged, Red and D-Red had no visible damage. RNA-seq data showed that a total of 3666 DEGs were screened out of all 28,306 genes detected, of which 1936 DEGs were upregulated and 1730 DEGs were downregulated in D-Red vs Gre. Transcriptomics and metabolomics showed that DEGs were significantly enriched in GO terms, such as in defense response, defense response to oomycetes, and response to reactive oxygen species, hydrogen peroxide, heat, salt stress, and biotic stimulus pathways. The KEGG analysis showed that DEGs were mainly enriched in secondary metabolism, carbohydrate metabolism, energy metabolism, and lipid metabolism. Anthocyanin synthesis genes may be regulated by transcription factors such as ERF, MYB, NAC, bHLH and various LRR-type receptor-like protein kinase (LRR-RLK) family genes. In conclusion, the accumulation of anthocyanins significantly increased from green to red in grape leaves during autumn low-temperature, improving the cold resistance of grape leaves.