Differential attachment by conidia of the endophyte, Discula umbrinella (Berk. & Br.) Morelet, to host and non‐host surfaces

Abstract

SUMMARYDiflFerential attachment of conidia to leaves of different species (host and non-host) has been observed in the endophytic fungus, Discula umbrinella (Berk. & Br.) Morelet, a deuteromycete known to cause occasional epidemics of anthracnose in beech stands. On beech leaves, attachment gradually increased over 24 h and reached a maximum after 16-24 h; there were small differences in attachment between conidia suspended in water and those in HEPES buffer. The range of variation of results obtained with conidia suspended in HEPES was smaller but the adhesion was clearly enhanced. The adhesion of conidia to the host surface was highest at pH 5, and decreased with increasing pH. Heat and chemical treatments significantly reduced attachment. Two factors (or groups of factors) are likely to be involved in the recognition process. The first is heat-labile, the second one could be a non-protein molecule present on the conidial surface and actively recognized by the host. The physiological similarity between endophytes and other symbionts is briefly discussed.

Fine structure of the extracellular sheath and cell walls inOphiostoma novo-ulmigrowing on various substrates

“…2 in O'Connell et al (1996), and in Fig. 1 in Toti et al (1992), which is similar to that shown in some of our illustrations (Fig. 41).…”

“…41). In Discula umbrinella (Toti et al 1992), transwall MFS-like structures are also distinguishable. A ciliiform appearance of the sheath (called fibrillar) is detectable in some of the illustrations by Green et al (1995).…”

“…First, in our view, structures analogous to MFS can be recognized in many published illustrations of various fungi studied with different techniques. For instance, one may refer to certain illustrations of samples from fungi fixed by freeze substitution (Hoch 1986;Bourett and Howard 1990;Kwon et al 1991;Van Dyke and Mims 1991) or high-pressure freezing (Toti et al 1992;O'Connell et al 1996), two techniques that are specifically considered to provide particularly life-like preservation of fungal structures. A microfilamentous organization of the ES (which was mentioned to extend several microns from the cell) is clearly evident in the material labelled ECM in Figs.…”

“…The accumulation of extracellular material around fungal cells, and information on its peculiarities as related to growth conditions and cell types, has received increasingly greater attention since it was first mentioned at the end of the 1960s (for example, see : Jones 1968;Colotelo 1978;Evans et al 1981;Beckett et al 1990;Larsen and Green 1992;Chaubal et al 1991;Toti et al 1992;Nicole et al 1993Nicole et al , 1994Nicole et al , 1995Green et al 1995;Nicholson and Kunoh 1995;Perotto et al 1995;Nicholson 1996;Cole et al 1996;O'Connell et al 1996;Pain et al 1996;Tenberge et al 1996). Such material has been given various names, but currently the term extracellular sheath (ES) seems to be the most commonly used.…”

Forest structure and fungal endophytes

“…The dominant fungal species are usually presumed to be specific to the host tree species or closely related species (see e.g. Gennaro et al 2003) because each host species usually harbours a characteristic assemblage of endophytic fungi (Barklund 1987;Danti et al 2002;Stone 1987;Toti et al 1992;Viret et al 1994; but see e.g. Suryanarayanan et al 2003).…”