VIEW ARTICLE

Cytology and Histology

Infection of Stylosanthes guianensis and S. scabra by Colletotrichum gloeosporioides. H. J. Ogle, Department of Botany, University of Queensland, St. Lucia, QLD 4067, Australia; D. H. Gowanlock(2), and J. A. G. Irwin(3). (2)Plant Pathology Branch, Department of Primary Industries, Meiers Road, Indooroopilly, QLD 4068, Australia; (3)Department of Botany, University of Queensland, St. Lucia, QLD 4067, Australia. Phytopathology 80:837-842. Accepted for publication 8 February 1990. Copyright 1990 The American Phytopathological Society. DOI: 10.1094/Phyto-80-837.

Penetration and postpenetration development were investigated quantitatively and qualitatively by light and scanning electron microscopy. Penetration commenced by 24 hr after inoculation on most interactions and continued until at least 96 hr on some. The overall level of penetration was very low (<9%). After penetration, a vesicle formed within the epidermal cell beneath the appressorium. In compatible interactions, this cell plus two to four adjacent cells were usually filled with hyphae before the fungus spread intra- and intercellularly into the mesophyll. ?Runner? hyphae emerged from the epidermal cells to grow subcuticularly or, more often, superficially, initiating new infections without the formation of appressoria. In incompatible interactions, colonies ceased growth, increased in size very slowly or apparently decreased in size. Most infections were restricted to one cell. No ?runner? hyphae were observed. Host cell response to infection varied from the deposition of apposition layers on the inner surface of the epidermal cell wall or the aggregation of granular cytoplasm beneath an appressorium to browning of the cell wall and contents.