Accumulation and cross-linkage of β-1,3/1,6-glucan lead to loss of basal stipe cell wall extensibility in mushroom Coprinopsis cinerea

The mature basal stipe of mushroom Coprinopsis cinerea loses wall extensibility. We found that an endo-β-1,3-glucanase ENG from C. cinerea could restore mature basal stipe wall extensibility via pretreatment such that the ENG-pretreated basal stipe walls could be induced to extend by chitinase ChiIII. ENG pretreatment released glucose, laminaribiose, and 3-O-D-gentiobiose-D-glucose from the basal stipe walls, consistent with ENG-digested products of β-1,6-branched β-1,3-glucan. Different effects of endo-β-1,3-glucanase ENG and exo-β-1,3-glucanase EXG pretreatment on the structure, amount and ratio (β-1,3-glucoside bonds to β-1,6-glucoside bonds) of products from the basal stipe and the apical stipe cell walls, respectively, and on the cell wall extensibility and the cell wall ultra-architecture of the basal stipes were analyzed. All results demonstrate that the more accumulation and cross-linkage of β-1,6-branched β-1,3-glucan with wall maturation lead to loss of wall extensibility of the basal stipe regions compared to the apical stipe cell walls.