Distribution of cell wall components in Sphagnum hyaline cells and in liverwort and hornwort elaters

Abstract

Spiral secondary walls are found in hyaline cells of Sphagnum, in the elaters of most liverworts, and in elaters of the hornwort Megaceros. Recent studies on these cells suggest that cytoskeletal and ultrastructural processes involved in cell differentiation and secondary wall formation are similar in bryophytes and vascular plant tracheary elements. To examine differences in wall structure, primary and secondary wall constituents of the hyaline cells of Sphagnum novo-zelandicum and elaters of the liverwort Radula buccinifera and the hornwort Megaceros gracilis were analyzed by immunohistochemical and chemical methods. Anti-arabinogalactan-protein antibodies, JIM8 and JIM13, labeled the central fibrillar secondary wall layer of Megaceros elaters and the walls of Sphagnum leaf cells, but did not label the walls of Radula elaters. The CCRC-M7 antibody, which detects an arabinosylated (1-->6)-linked beta-galactan epitope, exclusively labeled hyaline cells in Sphagnum leaves and the secondary walls of Radula elaters. Anti-pectin antibodies, LM5 and JIM5, labeled the primary wall in Megaceros elaters. LM5 also labeled the central layer of the secondary wall but only during formation. In Radula elaters, JIM5 and another anti-pectin antibody, JIM7, labeled the primary wall. The distribution of arabinogalactan-proteins and pectic polysaccharides restricted to specific wall types and stages of development provides evidence for the developmental and functional regulation of cell wall composition in bryophytes. Monosaccharide-linkage analysis of Sphagnum leaf cell walls suggests they contain polysaccharides similar to those of higher plants. The most abundant linkage was 4-Glc, typical of cellulose, but there was also evidence for xyloglucans, 4-linked mannans, 4-linked xylans and rhamnogalacturonan-type polysaccharides.

Biochemical determinants of litter quality in 15 species of Sphagnum

“…Mellegård et al 2009). Conversely, carbohydrate polymers (Turetsky et al 2008;Maksimova et al 2013), specifically cellulose microfibrils of secondary cell walls (Kremer et al 2004), confer structural integrity to the walls of hyaline cells.…”

“…All these properties are homologous with the roles of lignin in tracheophytes. In addition, the fibrils are strongly stained by ruthenium red stain, which indicates high density of sphagnan (Kremer et al 2004;Ballance et al 2012) that may serve as further protection against enzymatic degradation. Phenolic polymers seem to be responsible also for the rigidity of Sphagnum stems and branches as we observed considerable shoot softening after the delignification (holocellulose preparation).…”

“…Bryophytes do not synthesize Btrue^lignin (Kremer et al 2004;Maksimova et al 2013), which strengthens the cell walls of vascular plants (tracheophytes) and shields polysaccharides within the walls against microbial degradation (Talbot and Treseder 2012;Berg 2014). Similar to true lignin, the lignin-like phenolics in Sphagnum are thought to shield the polysaccharides by forming an amorphous coat on the cell wall surface (Tsuneda et al 2001).…”

Substrate-induced growth and isolation of Acidobacteria from acidic Sphagnum peat

“…Most organic acids were either poorly or not utilized. However, all isolates from peat were capable of utilizing galacturonic acid, a characteristic component of the cell wall in Sphagnum spp (Clymo, 1963(Clymo, , 1964Kremer et al, 2004), which is released during moss debris decomposition. None of our isolates including strain KMR, which was isolated on agar medium with methanol, were capable of methylotrophic growth.…”

Helical growth in plant organs: mechanisms and significance

“…If the link between the twin helices is cut at both ends, the elaters do not coil (Ingold, 1939). Primary and secondary cell wall layers have different polysaccharide compositions in the liverwort Radula buccinifera (Kremer et al, 2004), and their differential contraction during drying might be the basis of coiling.…”