Dissecting the differences of physical properties, structure, and metabolite content between Apocynum pictum and Apocynum venetum fibers

As a high-quality fiber source, Apocynum has great economic value. However, research on its bast properties, especially comparisons among different Apocynum species, is limited. In this study, we compared the bast qualities of two common Apocynum varieties, Apocynum pictum ( A. pictum ) and Apocynum venetum ( A. venetum ), aiming to offer breeding insights for suitable Apocynum fiber-production varieties. We conducted an integrated analysis of physical traits and metabolomic profiles to uncover the biochemical basis of fiber quality. Results showed that A. venetum had a 42.86 % higher tenacity than A. pictum . However, the two varieties were comparable in terms of fiber length, whiteness, UV protection factor, and UVA rejected rate. We observed both fiber types via scanning electron microscopy (SEM), revealing that A. venetum fibers have a rougher surface with more adhered metabolites than A. pictum fibers. Chemical composition analysis revealed that A. venetum fibers contained significantly higher levels of cellulose (increased by 66.67 %) and pectin, but less lignin (decreased by 59.09 %), than A. pictum fibers, a profile that is highly favorable for spinnability and fiber performance. Moreover, widely targeted metabolomics further revealed that A. venetum fibers have an enrichment of 507 differentially accumulated metabolites, primarily flavonoids and phenolic acids. Based on our results, it can be concluded that A. venetum , with its superior tenacity, optimized chemical composition, and enriched functional metabolites, is a more promising and sustainable source for functional textile breeding compared to A. pictum . • venetum has better physical properties compared to A. pictum. • venetum has higher levels of flavonoids and phenolic acid metabolites than A. pictum through metabolomics. • venetum is more promising for sustainable functional textile breeding.