in the genera Ceratocystis Ellis & Halsted (Microascales) and
Ophiostoma H. & P. Sydow (Ophiostomatales) and their asexual forms
are collectively referred to as the ophiostomatoid fungi. This name arises from
their morphological similarities and convergent evolution of morphological
structures adapted to insect dispersal (Wingfield et al., 1993). These
two genera include important tree pathogens that typically infect
wounds visited or made by their insect vectors. Well-documented examples of tree
pathogens are O. ulmi (Buisman) Nannf. and O. novo-ulmi Brasier,
responsible for the Dutch Elm disease pandemics in Europe and North America,
C. fagacearum (Bretz) Hunt, a damaging wilt pathogen of Quercus
spp. in the USA (Sinclair & Lyon, 2005) and species in the C. fimbriata
sensu lato complex (Kile, 1993). There are also many saprotrophic species
that cause blue-stain of lumber, reducing its commercial value (Seifert
little information is available regarding diseases of native trees in South
Africa and until recently, only one pathogen, Ceratocystis
albifundus, the cause of wattle wilt of non-native Acacia mearnsii
trees, was known from these trees. The fungus was first reported (as C.
fimbriata) from native Protea spp. in the 1970's (Gorter 1977), but
was not known from diseases of native trees. In recent studies C.
albifundus, has been found on seven native tree genera (Roux et al.,
2007), supporting the view that the fungus is native to South Africa (Barnes
et al., 2005, Roux et al., 2001). This provided motivation to
determine whether other ophiostomatoid fungi occur on native trees in the
were conducted in three main areas of South Africa where native trees occur
abundantly. These included the Kruger National Park (Mpumalanga Province),
Leeuwfontein Collaborative Nature Reserve (Gauteng Province) and Groenkloof
Forest (Tsitsikamma Forests, Western Cape Province). Wounds from which samples
were collected included damage caused by elephants (FIG A), kudu, eland (FIG B),
wind as well as those made artificially by local traditional healers when they
collect bark and wood for medicinal purposes (FIG C). Fungi isolated from
samples were identified using morphological studies and multigene sequence
Ceratocystis and Ophiostoma isolates were collected from eight
native tree genera spanning six different families. These included Acacia
nigrescens (Leguminosae), Combretum zeyheri Sond. (Combretaceae),
Sclerocarya birrea (Anacardiaceae), Burkea africana Hook.
(Leguminosae), Faurea saligna Harvey (Proteaceae), Ocotea bullata
(Burch.) Baill. (Lauraceae), Rapanea melanophloeos (Myrsinaceae) and
Terminalia sericea Burch. ex Dc. (Combretaceae).
fungal species were identified from the native trees in this study, three of
which represent new species. The fungi included C. albifundus, O.
quercus, and Pesotum fragrans. Previously unknown taxa were described
as Ceratocystis tsitsikammensis (FIG D)
(referring to the Tsitsikamma forests of South Africa), infecting
Rapanea melanophloeos trees; Ceratocystis savannae
(FIG E) (referring to the Savanna vegetation type
where the fungus was found), infecting Acacia nigrescens and Combretum
zeyheri trees; Ophiostoma longiconidiatum
(FIG F) (referring to the unusually long
conidia found in the anamorph state of this fungus). Of these fungi, only C.
tsitsikammensis appears to be capable of causing disease, resulting in
serious lesions on R. melanophloeoes trees in green-house inoculation
made in this study have clearly shown that, the diversity of ophiostomatoid
fungi infecting native trees in South Africa is poorly known. Future studies
similar to this one will most likely reveal many other species, some of which
could have economic and ecologic importance.
NG, Jacobs K, de Beer ZW, Wingfield MJ, Roux J. 2008. Ceratocystis
and Ophiostoma species, including three new taxa, associated with wounds
on native South African trees. Fungal Diversity 29: 37-59.