VIEW ARTICLE

Ecology and Epidemiology

Perforation and Lysis of Hyphae of Rhizoctonia solani and Conidia of Cochliobolus miyabeanus by Soil Myxobacteria. Y. Homma, Department of Agronomy, Shikoku National Agricultural Experiment Station, Zentsuji, Kagawa, 765 Japan, Present address: Department of Environmental Biology, National Institute of Agro-Environmental Sciences, Kannondai 3-1-1, Yatabe, Tsukuba, Ibaraki, 305 Japan; Phytopathology 74:1234-1239. Accepted for publication 22 May 1984. Copyright 1984 The American Phytopathological Society. DOI: 10.1094/Phyto-74-1234.

Pigmented hyphae of Rhizoctonia solani and conidia of Cochliobolus miyabeanus were lysed during burial for 4 wk in field soils. Many small perforations (0.1- 2.4 μm; average 0.4 μm) and hollows etched to various depths were observed by SEM in cell walls of the propagules. A species of myxobacteria was isolated from hyphae and conidia in various stages of lysis and cultured on conidia of C. miyabeanus suspended in 10% soil extract. The dendriform colonies advanced by streaming at 50- 70 μm/hr as groups of cells. Rods crowded around the fungal cells, perforated the cell walls, and emptied the cell contents completely within 6- 12 hr after contact between a streaming colony tip and the cell wall. The streaming colony left the emptied cell with many perforations and hollows in the walls that matched those observed on fungal material recovered from soil. Based on size and shape of the vegetative rods, fruiting bodies, and myxospores, the bacteria seem to fit systematically into the family Polyangiaceae and the genus Polyangium, but species identification cannot be made yet with certainty.