CELL-WALL ALTERATIONS IN LOBLOLLY-PINE WOOD DECAYED BY THE WHITE-ROT FUNGUS, CERIPORIOPSIS-SUBVERMISPORA

Ultrastructural, immunocytochemical and UV absorption spectroscopy tec hniques were used to elucidate the progressive changes that occur with in woody cell walls during decay by Ceriporiopsis subvermispora. After only 2 weeks of incubation, uranyl acetate staining revealed a diffus e electron dense zone in the secondary wall near hyphae and around the outer circumference of the wall. The extent of cell wall staining inc reased with longer fungal incubation. No staining occurred in sound un altered cell walls. Proteins of varying molecular weights (insulin, 57 30 Da; myoglobin, 17 600 Da; ovalbumin, 44 287 Da) were infiltrated in to sound and decayed wood followed by immunogold labelling and transmi ssion electron microscopy. Insulin readily penetrated into the outer m ost regions of secondary walls of wood cells after 2 weeks of decay. M yoglobin was first observed to penetrate cell walls at 4 weeks of degr adation and ovalbumin was found after 8 weeks in wood with advanced st ages of decay where extensive cell wall disruption was evident. None o f the proteins used were localized within cell walls of untreated, con trol wood samples. UV microspectrophotometry demonstrated a progressiv e loss of absorbance at 240 and 280 nm within the secondary walls and middle lamellae at various sampling times throughout the duration of t he decay study. (C) 1997 Elsevier Science B.V.