Penetrating Structures of Anaerobic Rumen Fungi in Cattle and Swamp Buffalo

Rhizoids of anaerobic fungi colonizing fragments of guinea grass and rice straw in the rumen of cattle and swamp buffalo produced appressorium-like structures for penetration of the plant cell walls. These structures were generally lobed vesicles with fine penetration pegs, which penetrated through the cell wall and then expanded and continued their growth in adjacent cells, forming normal rhizoids which would in turn produce more ‘appressoria’ for penetration of the next cell. Their size and form varied with the size of the cell in which they developed. Small, flat ‘appressoria’ were produced in cells with small lumina while bigger and longer ‘appressoria’ developed in larger cells. ‘Appressoria’ were clearly observed in rhizoids of fungi colonizing the plant fragments about 1 h after incubation in the rumen and were produced in rumen fungi with spherical, oval or ovoid sporangia.