Diversity and ecology of ophiostomatoid fungi and arthropods associated with proteaceae infructescences

[摘要] ENGLISH ABSTRACT:Five new species of ophiostomatoid fungi, colon ising the infructescences ofserotinous Protea species, have recently been discovered in South Africa. Priorto this, ophostomatoid fungi were thought to be restricted to the NorthernHemisphere. The discovery of these five species thus extensively expanded theknown geographical range of these fungi, now also to include the SouthernHemisphere. Since this discovery, few studies have focused on the interestingecology of this group, which is uniquely adapted for spore dispersal byarthropods. Studies focussed on ophiostomatoid fungi provide an uniqueopportunity to study inter-organism interactions between fungi, their host plantsand the arthropods responsible for their spore dispersal. Very few similar studieshave been undertaken, particularly in the Fynbos Biome, to which most of oureconomically important Protea species are confined. The current study providesinsight into some ecological aspects of these complex interactions.The seasonal distribution of the ophiostomatoid fungi associated with theinfructescences of members of the Proteaceae was investigated. Definiteseasonal patterns were observed, with peak fungal colonisation occurring duringthe wetter winter months. While determining the host specificity of these fungi, anew Protea host for Ophiostoma splendens was identified, and a new species ofRhyncomeliola was discovered. All ophiostomatoid species native to Fynbos inthe Stellenbosch region are exclusively associated with the infructescences ofspecies in the plant genus Protea.By employing a multiplex Polymerase Chain Reaction (PCR), a set of groupspecific primers was developed for the identification of South African Ophiostomaand Gondwanamyces fungal DNA. This newly developed method was used toscan arthropods collected from the infructescences of P. repens for the presenceof 0. splendens and G. proteae spores. By using these group-specific primers, three insects possibly responsible for long range dispersal of fungal spores wereidentified. Three further insect species, possibly contributing to the short-rangedispersal of ophiostomatoid spores, were also implicated through this method.All arthropods associated with the fruiting structures of selected members of theProteaceae were also investigated. A total of 62 pseudospecies (ca. 7500individuals), belonging to 45 different arthropod families, were collected.Proteaceae species with larger fruiting structures housed more arthropod speciesand higher numbers of individuals than Proteaceae taxa with smaller fruitingstructures. Some plant species housed similar arthropod communities, whileothers housed unique suites of arthropods. Seasonal patterns in arthropodnumbers were observed, and it was found that, in most instances, arthropodnumbers peaked during the autumn and winter months.Twenty-five fungal taxa were isolated from various Proteaceae arthropods, manyof which are genera known to include Proteaceae pathogenic species.Ophiostomatoid fungi have a saprophytic relationship with their Protea hosts, andmay deter some of these potentially harmful fungi from colon ising theinfrutescences. Some fungi showed a high degree of specificity towards potentialvectors, while others were found on a diverse range of arthropods.This study highlights the existence of complex inter-organismal interactionswithin the Fynbos Biome, a study area where the interactions between plants,fungi and insects have been grossly neglected. The few studies that have beenconducted 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 isimportant to obtain a holistic view in any ecological study that focuses oninteractions between different suites of organisms. Ultimately this will aid in thedevelopment of better conservation strategies. This study thus provides a muchneededstart in studies on multi-organismal interactions in the Fynbos Biome.

[发布机构] Stellenbosch University