CONICET | Buscador de Institutos y Recursos Humanos

Cell wall chemistry in the coencocytic green seaweed Codium vermilara (Olivi) Chiaje (Bryopsidales, Chlorophyta) is well understood. These cell walls are composed of major amounts of neutral beta 1,4-D-mannans (Mn), sulfated polysaccharides (SPs), which include pyranosic arabinan sulfates (ArpS), pyruvylated galactan sulfates (pGaS), and mannan sulfates (MnS); also minor amounts of O-glycoproteins are present. In this study, cell wall samples of C. vermilara were investigated with regard to their monosaccharide composition and infrared spectra (by Fourier Transformed Infrared spectroscopy coupled to Principal Component (FTIR-PC) analysis). Samples from three different populations of C. vermilara from Argentine coast showed: 1) an important variation in the relative arabinan content, which increases from north to south, and 2) a measurable degree of cell wall variability in the sulfate distribution between the different sulfated polysaccharides, independently of the amount of each polysaccharide present and of total sulfate content. When cell wall composition was analyzed over three consecutive years in a single geographical location, the quantity of Mn and overall sulfate content on SPs remained constant, whereas pGaS:ArpS molar ratio changed over the time. Besides, similar cell wall composition was found between actively-growing and resting zones of the thallus, suggesting that cell wall composition is independent of growth stage and development. Overall, these results suggest that C. vermilara has developed a mechanism to adjust the total level of cell wall sulfation by modulating ArpS:pGaS:MnS molar ratio and also by adjusting the of sulfation level in each type of polymer, whereas non-sulfated Mn, as the main structural polysaccharide, does not change over the time or growing stage.