Pattern of delignification inAilanthus excelsaRoxb. wood byInonotus hispidus(Bull.: Fr.) Karst.

Abstract

The pattern of delignification in Ailanthus excelsa Roxb. wood, naturally infected by Inonotus hispidus (Bull.: Fr.) Karst., was studied by light microscopy. Inonotus hispidus produced a typical pattern of soft rot decay even though it is grouped with white rot basidiomycetes. Fungal hyphae colonised all cell types of the secondary xylem but more damage was observed in xylem fibres. In the early stage, infection commenced on the cell wall corners and middle lamellae of the fibre wall without any pronounced effect on the primary and secondary wall layers. Delignification of fibre wall became apparent when all cell types became completely invaded by fungal hyphae. It started from within the lumina towards the middle lamellae, occurring initially in the immediate vicinity of hyphae growing on the luminal surface by forming an erosion trough. At an advanced stage of decay, localised degradation of lignin, cellulose and hemicellulose resulted in the formation of small cavities within the secondary walls (S 2 ) of fibres. These cavities were never observed to contain any fungal hyphae. Though the vessels were resistant to infection, xylem rays and fibres were relatively less resistant to attack by I. hispidus. In severe infection, vessel lumens were found to be filled with sclerotic tissue which blocked them, resulting in complete collapse. The formation of cavities and the extent of cell wall damage are described in detail.

A New Heart Rot Disease in <i>Ailanthus excelsa</i> Roxb. Caused by <i>Navisporus floccosus</i> (Bres.) Ryvarden

“…In the present paper N. floccosus also causing severe heart rot. The fruiting bodies were also observed on relatively young branches of 5-7 inch in diameter (Koyani et al 2010). In the present paper the fruiting bodies were observed at Butt region.…”

“…(Orwa et al 2009). Inonotus hispidus produced a typical pattern of soft rot decay even though it was grouped with white rot basidiomycetes (Koyani et al 2010). In the present paper the N. floccosus produced typical white rot decay.…”

“…In Ailanthus infection by I. hispidus was initiated during the monsoon when moisture levels were very high and the cut branch stubs were exposed to rain (Koyani et al 2010). But in the present paper the fungi infection was started during monsoon, grown extensively and form large basidiocarps on living tree in later stages.…”

“…are other rot fungi that attack this tree International Letters of Natural Sciences Vol. 6 (Koyani et al 2010). In the present study another white rot fungi like N. floccosus was causing heart rot in wood.…”

“…P. Karst. delignifing the wood of A. excelsa (Koyani et al 2010). Earlier the fungus was reported from east Africa but N. floccosus (Bres.)…”