The Cell Wall of Seagrasses: Fascinating, Peculiar and a Blank Canvas for Future Research

Abstract

Seagrasses are a polyphyletic group of angiosperm plants, which evolved from early monocotyledonous land plants and returned to the marine environment around 140 million years ago. Today, seagrasses comprise the five families Zosteraceae, Hydrocharitaceae, Posidoniaceae, Cymodoceaceae, and Ruppiaceae and form important coastal ecosystems worldwide. Despite of this ecological importance, the existing literature on adaption of these angiosperms to the marine environment and especially their cell wall composition is limited up to now. A unique feature described for some seagrasses is the occurrence of polyanionic, low-methylated pectins mainly composed of galacturonic acid and apiose (apiogalacturonans). Furthermore, sulfated galactans have been detected in some species. Recently, arabinogalactan-proteins (AGPs), highly glycosylated proteins of the cell wall of land plants, have been isolated for the first time from a seagrass of the baltic sea. Obviously, seagrass cell walls are characterized by new combinations of structural polysaccharide and glycoprotein elements known from macroalgae and angiosperm land plants. In this review, current knowledge on cell walls of seagrasses is summarized and suggestions for future investigations are given.

Compositional stability of sediment microbial communities during a seagrass meadow decline

“…In contrast to Gammaproteobacteria and Desulfobacterota, a higher relative abundance of Bacteroidota at the vegetated site may be influenced by the presence of the plant itself. Seagrass cell walls contain polysaccharides like cellulose (Pfeifer and Classen, 2020) and Bacteroidota have been identified as decomposers of macromolecules such as cellulose (Thomas et al, 2011). The differences between the vegetated and nonvegetated sediment communities were also reflected in the higher proportion of Campylobacterota related sequences at the vegetated site.…”

Early evidence of the impacts of microplastic and nanoplastic pollution on the growth and physiology of the seagrass Cymodocea nodosa

“…For leaves of C. nodosa, without stomatal apertures as occurs in seagrasses, it is possible to hypothesize a cuticular penetration of nanomaterials. Epidermal cells display a thin cuticle and subcuticular cavities (Kuo and den Hartog, 2006) and specific cell wall composition (Pfeifer and Classen, 2020), which probably facilitate the entry of NPs by altering the dynamic behaviour and the diameter of the cell wall pores. However, even in terrestrial plants, an entry of nanomaterials via aqueous pores of the leaf cuticle has been demonstrated, in parallel to the more widespread stomatal pathway (Larue et al, 2014) thus supporting our hypotheses.…”

“Neptune Balls” Polysaccharides: Disentangling the Wiry Seagrass Detritus

“…One other study [93] investigated the bioethanol production from P. oceanica residues and showed high yield for that material. Therefore, in the direction of reuse as biofuels, some steps are already taken (also partly covered in the review by [94]).…”