The influence of pectins and cellulose in the mechanical and adhesive properties of seed mucilage.

Several plant seeds release a mucilaginous envelope through hydration, rich in pectins and stabilized by cellulose fibers. This mucilage aids in seed protection, development, and adhesion for dispersal. This study aimed to separate the effects of pectins and cellulose fibers by using pectinase to remove mucilage pectins, leaving cellulose arrays, and performing wet and dry pull-off force measurements on seeds of three plant species: Salvia hispanica (Chia), Collomia grandiflora (Collomia) and Linum usitatissimum (Flax). We used light and scanning electron microscopy to confirm partial pectin removal and intact cellulose fibers. Pull-off force measurements revealed similar wet adhesive properties and E-moduli in S. hispanica and C. grandiflora seeds before and after pectin removal. L. usitatissimum seeds, lacking cellulose fibers, exhibited significantly lower wet and dry adhesion forces post-pectin removal. Desiccation dynamics showed shorter desiccation times after pectin removal in all three species. Results indicated that adhesion forces in seed mucilage with cellulose fibers did not change significantly after pectin removal, suggesting that cellulose fibers contribute to the adhesive properties of seed mucilage, while pectins might not play an exclusive role in adhering to surfaces.