Insights into cell wall architecture of developing nettle bast fibers through immunohistochemical analysis

Title : Insights into cell wall architecture of developing nettle bast fibers through immunohistochemical analysis

Abstract:

Urtica dioica L. (stinging nettle) is increasingly recognized as a valuable fiber crop, combining agronomic adaptability with the production of bast fibers possessing remarkable mechanical properties. The performance of these fibers is closely associated with the structure and composition of their cell walls, which undergo extensive modifications during differentiation. To gain insight into the dynamics of cell wall assembly during fiber development, we investigated the spatial distribution of selected pectic and hemicellulosic polysaccharides in developing nettle bast fibers using immunohistochemical techniques.Transverse stem sections obtained from apical and basal internodes, representing elongating and fully differentiated fibers, respectively, were analyzed with monoclonal antibodies targeting homogalacturonans with different degrees of methyl esterification (JIM5 and JIM7) and xyloglucan epitopes (LM25). Distinct developmental changes in cell wall polymer distribution were observed.In elongating fibers, the JIM7 epitope corresponding to highly methyl-esterified pectins was detected throughout the cell wall, with localized regions exhibiting enhanced fluorescence intensity. Following fiber maturation, JIM7 labelling remained prominent and extended across the entire gelatinous layer (G-layer), revealing an unexpected persistence of highly methyl-esterified homogalacturonans in mature cell walls. Low methyl-esterified pectins, identified by JIM5, displayed a punctate pattern in young fibers but became strongly enriched at fiber–neighbor cell interfaces in basal internodes. Immunolabelling with LM25 showed a developmental shift from a predominantly junction-associated localization in elongating fibers to an intense and widespread distribution throughout the walls of mature fibers.The observed changes indicate that bast fiber differentiation in U. dioica involves substantial remodeling of cell wall polysaccharide organization. In particular, the extensive occurrence of highly methyl-esterified pectins within the mature G-layer suggests previously underappreciated structural complexity and raises new questions regarding their contribution to fiber mechanics and cell wall functionality. These findings provide further insight into the developmental biology of nettle fibers and may support future efforts aimed at optimizing fiber quality for sustainable industrial applications.

Biography:

Dr. Penelope Sotiriou is a plant biologist and laboratory teaching staff member at the National and Kapodistrian University of Athens, Greece. Her research interests focus on plant cell wall biology, plant development, and morphogenesis. She has extensive experience in the study of cell wall polysaccharides, including their biosynthesis, distribution, and role in plant cell differentiation. Her publications have addressed topics such as cell wall regeneration in protoplasts, mesophyll and pavement cell morphogenesis, and the spatial organization of cell wall matrix components in higher plants. Through both research and teaching, she contributes to the advancement of plant biology and the understanding of how cell wall architecture influences plant structure and function.