Degradation of the Gelatinous Layer in Aspen and Rubberwood by the Blue Stain Fungus Lasiodiplodia Theobromae

Abstract

Studies on the degradative ability of the blue stain fungus Lasiodiplodia theobromae (Pat.) Griffon ' Maublanc have shown several strains to cause significant weight losses (c. 20%) in wood of temperate and tropical species, aspen (Populus tremula) and rubberwood (Hevea brasiliensis), both species that commonly form tension wood. In addition to the consumption of soluble carbohydrates, major changes occurred in the ultrastructure of fibre cell walls, with a rapid attack of the G-layer of the gelatinous fibres. Following G-layer degradation, earlywood fibres of both species showed true cell wall degradation with pronounced erosion attack, suggesting that prior destruction of the G-layer afforded greater accessibility and ease of attack of the outer secondary cell wall layers.