Introduction to Fungi, Third Edition

284 HEMIASCOMYCETES
Fig10.13 Eremothecium coryli.(a)Vegetative
growth as a mass of hyphae and yeast cells. (b)
Ascus containing eight ascospores. Both
images to same scale.
Most members of the genus Saccharomycopsis
have been observed to behave as predacious
yeasts on leaf surfaces, i.e. they attack, penetrate
and digest the cells of other yeasts (Fig. 10.12).
This phenomenon is different from that of killer
yeasts because no toxins appear to be involved.
Instead, penetration and killing is brought
about mainly by cell wall-degrading enzymes,
notably b-(1,3)-glucanase (Lachance et al., 2000).
It is interesting to note that all those yeasts
capable of preying on others are incapable
of utilizing sulphate as a source of sulphur,
although not all yeasts deficient in sulphate
transport are predacious. Predation can be cannibalistic,
but many other yeasts belonging to
the Asco- and Basidiomycota are also attacked.
Clearly, the phylloplane is a highly competitive
environment.
10.7 Eremothecium
(Eremotheciaceae)
This genus contains five species which were
formerly classified in different genera but have
now been shown to be closely related by DNA
sequence analyses (Kurtzman, 1995; de Hoog
et al., 1998). Pseudohyphae and true hyphae are
present in culture, and vegetative reproduction
is often by budding yeast cells. Asci are formed
terminally or in intercalary positions, and
they contain 8 32 needle-shaped ascospores
(Fig. 10.13).
Eremothecium spp. are the only important
plant pathogens among the Hemiascomycetes
and can infect numerous plant species, causing
damage especially on cotton (Gossypium spp.).
They are transmitted by hemipteran insects
which may harbour inoculum in their stylet
pouches. The route of entry into the plant
is often via the stigma of the flower (Batra,
1973). Eremothecium (formerly Nematospora) coryli
(Fig. 10.13) causes a disease called stigmatomycosis
on a wide range of plants, including hazel
(Corylus).
In biotechnology, E. ashbyi and E. (Ashbya)
gossypii are used in fermentations for the