Glucose enhanced lignin accumulation in grapevine stems via promoting phenylpropanoid biosynthesis

The lignification of branches can promote the accumulation of nutrients, increase plant survival and resistance to biotic and abiotic stresses. As an important carbon source for plants, glucose is also the carbon skeleton for lignin synthesis. Grapevine is a perennial cash crop, and highly lignified branches are essential to ensure the growth of the grapevine plant and the development of the fruit. Here, ‘Red Globe’ grape (Vitis vinifera L.) plantlets were selected as the material and cultured with different concentrations of glucose: 0 g/L, 20 g/L, 40 g/L and 60 g/L glucose (G0, G20, G40 and G60). Among them, G0 group as control. Lignin, anthocyanins and glucose contents, plant height and microstructure were measured at each glucose concentration after 40-, 50-, and 60-day treatments. Transcriptome and metabolome were used to analyze the difference in genes and metabolites after 50 days of growth. After 50 days of cultivation, the lignin content in G40 group was the highest. And the xylem cells number also increased. To further, transcriptome and metabolome have identified a total of 3638 differentially expressed genes (DEGs) (including 245 TFs) and 510 differently accumulated metabolites (DAMs) in three comparison groups. In-depth joint analysis revealed that phenylpropanoid biosynthesis pathway significantly respond to exogenous glucose, and 37 DEGs were identified. Therefore, the phenylpropane biosynthesis pathway may be the key to exogenous glucose to increase lignin levels in grapes, with differential expression of genes being a top priority. These findings provide a new perspective for understanding the relationship between glucose and lignin in grape.