PART OF A SPECIAL ISSUE ON PLANT CELL WALLS Comparative glycan profiling of Ceratopteris richardii 'C-Fern' gametophytes and sporophytes links cell-wall composition to functional specialization

†BackgroundandAimsInnovationsinvegetativeandreproductivecharacterswerekeyfactorsintheevolutionaryhistoryof landplants and most of these transformations, including dramatic changes in life cycle structure and strat-egy, necessarily involved cell-wall modifications. To provide more insight into the role of cell walls in effectingchanges in plant structure and function, and in particular their role in the generation of vascularization, an anti-body-based approach was implemented to compare the presence and distribution of cell-wall glycan epitopesbetween (free-living) gametophytes and sporophytes of Ceratopteris richardii ‘C-Fern’, a widely used modelsystem for ferns.†MethodsMicroarraysofsequentialdiamino-cyclohexane-tetraaceticacid(CDTA)andNaOHextractionsofgame-tophytes, spores and different organs of ‘C-Fern’ sporophytes were probed with glycan-directed monoclonal anti-bodies. The same probes were employed to investigate the tissue- and cell-specific distribution of glycan epitopes.†Key Results While monoclonal antibodies against pectic homogalacturonan, mannan and xyloglucan widelylabelledgametophytic and sporophytic tissues,xylans were onlydetected in secondarycell walls of the sporophyte.The LM5 pectic galactan epitopewas restricted to sporophytic phloem tissue. Rhizoids and root hairs showed simi-larities in arabinogalactan protein (AGP) and xyloglucan epitope distribution patterns.†ConclusionsThedifferencesandsimilaritiesinglycancell-wallcompositionbetween‘C-Fern’gametophytesandsporophytes indicate that the molecular design of cell walls reflects functional specialization rather than geneticorigin. Glycan epitopes that were not detected in gametophytes were associated with cell walls of specializedtissues in the sporophyte.Key words: Ceratopteris richardii ‘C-Fern’, gametophyte, sporophyte, plant cell wall, glycan microarray,immunocytochemistry, monilophytes, pteridophyta.