Thesis (MSc)--University of Stellenbosch, 2002. / ENGLISH ABSTRACT: Five new species of ophiostomatoid fungi, colon ising the infructescences of
serotinous Protea species, have recently been discovered in South Africa. Prior
to this, ophostomatoid fungi were thought to be restricted to the Northern
Hemisphere. The discovery of these five species thus extensively expanded the
known geographical range of these fungi, now also to include the Southern
Hemisphere. Since this discovery, few studies have focused on the interesting
ecology of this group, which is uniquely adapted for spore dispersal by
arthropods. Studies focussed on ophiostomatoid fungi provide an unique
opportunity to study inter-organism interactions between fungi, their host plants
and the arthropods responsible for their spore dispersal. Very few similar studies
have been undertaken, particularly in the Fynbos Biome, to which most of our
economically important Protea species are confined. The current study provides
insight into some ecological aspects of these complex interactions.
The seasonal distribution of the ophiostomatoid fungi associated with the
infructescences of members of the Proteaceae was investigated. Definite
seasonal patterns were observed, with peak fungal colonisation occurring during
the wetter winter months. While determining the host specificity of these fungi, a
new Protea host for Ophiostoma splendens was identified, and a new species of
Rhyncomeliola was discovered. All ophiostomatoid species native to Fynbos in
the Stellenbosch region are exclusively associated with the infructescences of
species in the plant genus Protea.
By employing a multiplex Polymerase Chain Reaction (PCR), a set of group
specific primers was developed for the identification of South African Ophiostoma
and Gondwanamyces fungal DNA. This newly developed method was used to
scan arthropods collected from the infructescences of P. repens for the presence
of 0. splendens and G. proteae spores. By using these group-specific primers, three insects possibly responsible for long range dispersal of fungal spores were
identified. Three further insect species, possibly contributing to the short-range
dispersal of ophiostomatoid spores, were also implicated through this method.
All arthropods associated with the fruiting structures of selected members of the
Proteaceae were also investigated. A total of 62 pseudospecies (ca. 7500
individuals), belonging to 45 different arthropod families, were collected.
Proteaceae species with larger fruiting structures housed more arthropod species
and higher numbers of individuals than Proteaceae taxa with smaller fruiting
structures. Some plant species housed similar arthropod communities, while
others housed unique suites of arthropods. Seasonal patterns in arthropod
numbers were observed, and it was found that, in most instances, arthropod
numbers peaked during the autumn and winter months.
Twenty-five fungal taxa were isolated from various Proteaceae arthropods, many
of which are genera known to include Proteaceae pathogenic species.
Ophiostomatoid fungi have a saprophytic relationship with their Protea hosts, and
may deter some of these potentially harmful fungi from colon ising the
infrutescences. Some fungi showed a high degree of specificity towards potential
vectors, while others were found on a diverse range of arthropods.
This study highlights the existence of complex inter-organismal interactions
within the Fynbos Biome, a study area where the interactions between plants,
fungi and insects have been grossly neglected. The few studies that have been
conducted in this field have mostly focussed on a limited number of organisms,
and no wide-scale attempts, such as presented here, have been published. It is
important to obtain a holistic view in any ecological study that focuses on
interactions between different suites of organisms. Ultimately this will aid in the
development of better conservation strategies. This study thus provides a muchneeded
start in studies on multi-organismal interactions in the Fynbos Biome. / AFRIKAANSE OPSOMMING: Vyf nuwe ophiostoma-agtige fungus spesies is onlangs in die vrug-liggame van
Suid Afrikaanse Protea plante ontdek. Voor hierdie ontdekking, was die
algemene opvatting dat ophiostoma-agtige fungi beperk is tot die Noordelike
Halfrond. Die ontdekking van hierdie vyf spesies het dus die bekende
geografiese verspreiding van hierdie tipe fungi vergroot om nou ook die Suidelike
Halfrond in te sluit. Sederdien het min studies gefokus op die interesante
ekologie van hierdie groep, wat aangepas is vir spoorverspreiding deur
geleedpotiges. Studies wat fokus op die ophiostoma-agtige fungi voorsien 'n
unieke geleentheid om die inter-organismiese-interaksies tussen fungi, hul
gasheer plante en die geleedpotiges wat hul spore versprei, te bestudeer. Baie
min soortgelyke studies is al voorheen in die Fynbos Bioom, waar die meeste
van ons ekonomies-belangrike Protea spesies voorkom, onderneem. Die huidige
studie verleen meer inligting oor sommige ekologiese aspekte van hierdie
komplekse interaksies.
Seisoenale verspreidingspatrone van ophiostoma-agtige fungi geassosieer met
die vrug-liggame van lede van die Proteaceae, is ondersoek. Daar is defnitiewe
seisoenale patrone in die aanwesigheid van fungi gevind, met 'n piek in fungi
kolonisasie-getalle gedurende die vogtiger wintermaande. 'n Nuwe Protea
gasheer vir Ophiostoma splendens en 'n nuwe fungus spesie (Rhyncomeliola
sp.), is ontdek. Alle Fynbos ophiostoma-agtige spesies in die Stellenbosch area,
is beperk tot Protea spesies.
'n Multipleks Polimerase Ketting Reaksie is ontwikkel om die spesifieke DNS van
ophiostoma-agtige fungi te herken. Hierdie metode is gebruik om te toets vir die
aanwesigheid van spore van hierdie fungi op die liggame van geleedpotiges
(geassosieerd met P. repens). Hierdeur is drie insekte wat waarskynlik
verantwoordelik is vir die langafstand verspreiding van spore geidentifiseer. Drie verdere insekte wat moontlik verantwoordelik is vir die kortafstand verspreiding
van ophiostoma-agtige fungi is ook aangewys.
Alle geleedpotiges geassosieer met die vrugstrukture van geselekteerde lede
van die Proteaceae is ondersoek. 'n Totaal van 62 pseudo-spesies (omtrent
7500 individue), wat tot 45 families behoort, is versamel. Proteaceae spesies met
groter vrugstrukture het meer geleedpotige spesies en individue gehuisves as
taksa met kleiner vrugstrukture. Sommige plant spesies het soortgelyke
geleedpotige gemeenskappe gehuisves, terwyl unieke groepe geleedpotiges in
ander plante voorgekom het. Alhoewel die geleedpotiges seisonale variasies in
getalle geopenbaar het, het die meeste groepe 'n piek in getalle getoon
gedurende die herfs- en wintermaande.
Vyf-en-twintig fungi taksa is geïsoleer vanaf verskeie Proteaceae geleedpotiges.
Sommige van hierdie is genera wat Proteaceae patogeniese spesies insluit.
Sommige fungi het 'n hoë graad van spesifisiteit teenoor potensiële vektore
getoon, terwyl ander weer algemeen op verskeie geleedpotige spesies gevind is.
Hierdie studie dui op die bestaan van komplekse inter-organismiese-interaksies
in die Fynbos Bioom, in 'n area waar die studie van interaksies tussen plante,
fungi en insekte nog baie min aandag geniet het. Die beperkte aantal studies wat
tot dusver in hierdie veld onderneem is, fokus gewoonlik slegs op 'n paar
organismes. Geen grootskaalse studies, soos die een hier voorgelê, is al
gepubliseer nie. In enige ekologiese studie wat fokus op interaksies tussen
verskeie organismes, is dit belangrik om 'n holistiese siening te probeer verkry.
Uiteindelik sal dit bydra tot die ontwikkeling van beter bewarings-strategië.
Hierdie studie verleen dus 'n noodsaaklike begin tot studies op multiorganismiese-
interaksies.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/52807 |
| Date | 12 1900 |
| Creators | Roets, Francois |
| Contributors | Dreyer, L. L., Crous, P. W., Stellenbosch University. Faculty of Science. Dept. of Botany and Zoology. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | English |
| Type | Thesis |
| Format | 133 p. : ill. |
| Rights | Stellenbosch University |
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