Comparison of cell-wall polysaccharides from Nectria cinnabarina with those from the group of Nectria with Sesquicillium anamorphs

Alkali-extractable and water-soluble polysaccharides were purified from cel l walls of five species of Sesquicillium or its teleomorphs, Nectria lasiac idis and Nectria impariphialis, and from Nectria cinnabarina, the type spec ies of Nectria, a heterogeneous genus that belongs to the Hypocreales. Meth ylation and NMR analyses for determination of linkage types and structure w ere performed and indicated differences between the polysaccharides purifie d during the present study and those isolated from other nectrioid fungi, n amely the presence of 5-O-substituted galactofuranose (-->5)-Galf-(l -->) i n the main chain together with 2,6-di-O-substituted galactofuranose (--> 2, 6)-Galf-(1 -->) residues in Sesquicillium buxi and Sesquicillium pseudoseto sum. The polysaccharide from N. impariphialis was similar to those obtained from the above species, although an additional residue of 6-O-substituted glucopyranose (--> 6)-Glcp(1 -->), was detected in some side chains. In N. lasiacidis and Sesquicillium candelabrum the polysaccharide contained an ad ditional branching point of 5,6-di-O-substituted galactofuranose (--> 5,6)- Galf-(1 -->) linked to terminal N-acetylglucosamine GlcNAc-(1 -->). These c hains were linked to a small mannan core. All these polysaccharides showed major differences to the polysaccharide of N. cinnabarina, which was formed by a main chain of (1 --> 6)-beta -linked galactofuranose units almost ful ly branched at positions 2-O by either single residues of glucopyranose or acidic chains containing glucuronic acid and mannose.