Differential accumulation of secondary metabolites as indicators of graft incompatibility in Cyclocarya paliurus.

Cyclocarya paliurus, endemic to the subtropical regions of southern China, holds significant potential as a health product, with its leaf-derived secondary metabolites commanding considerable value. This study aimed to investigate the secondary metabolites associated with graft success in C. paliurus by selecting three clones and three provenances as grafting scions and rootstocks. The survival rates of various graft combinations were meticulously recorded. Targeted metabolic profiling of the graft union was employed to analyze the flavonoid and phenylpropanoid biosynthesis pathways in both compatible and incompatible graft combinations. The results indicate that phenylpropanoids preferentially accumulate in compatible graft unions, while flavonoids are more abundant in incompatible unions. In the grafted seedlings of C. paliurus, ferulic acid, glycitein, dihydromyricetin, pinocembrin, and apigenin exhibited distinct accumulation patterns. These findings revealed the regulatory patterns within the phenylpropanoid biosynthesis pathway for predicting graft success in C. paliurus. The insights are valuable for the optimization of C. paliurus grafting practices and for future breeding programs aimed at enhancing the species' horticultural and economic potential.