The fungal diversity of Pinaceae in Hong Kong
Abstract of the thesis entitled
THE FUNGAL DIVERSITY OF PINACEAE IN HONG KONG
Yeung Sze Yuen
for the degree of Master of Philosophy
at The University of Hong Kong
in January 2005
The fungal diversity occurring on needles of Keteleeria fortunei, Pinus elliottii and P. massoniana (Pinaceae) in Hong Kong has been investigated. Microscopic examination of needles yielded 48 taxa comprising 37 anamorphic fungi, three ascomycetes, one lower fungal taxon and one oomycete, while the number of non-sporulating taxa was seven. Two species new to science were described and illustrated. Fungal diversity on P. elliottii (31 taxa) was highest. Dominant taxa on all hosts were fast-growing anamorphic fungi, such as Cladosporium cladosporioides, Trichoderma sp. and a non-sporulating white hyphal form.
The effects of biogeography, seasonality, needle chemistry and needle morphology on fungal communities were investigated. Geographical location within a narrow range appeared to have little effect upon species composition. Cluster analysis (Bray-Curtis similarity) and multi-dimensional scaling (MDS) showed that fungal communities on Keteleeria fortunei needles differed between wet and dry seasons, but this was not the case for Pinus elliottii and P. massoniana. Fungal succession on decaying L-type needles (dead needles, brown in colour) of P. massoniana revealed Myrothecium sp. and Lophodermium pinastri as primary colonisers of pine litter. A shift in fungal community was also observed during different decay stages. Needles of Casuarina equisetifolia and Pinus species are morphologically similar and fungal communities on them were also similar. This indicates that leaf structure may be more important in determining fungal communities than host relationships. However, since a culture-based technique was used to reveal fungi, this may also affect the make-up of the fungal communities identified. Pearson correlation was used to explore the relationship between chemical composition of needles and fungal diversity.
Concentrations of phenolics, calcium, potassium and sodium were negatively correlated with species richness.
Denaturing Gradient Gel Electrophoresis (DGGE) was used to determine the genotypic diversity of fungi occurring on needles of Pinaceae species. Living needles (attached to branches), dead L-type needles and F-type needles (dead black needles, with lower moisture content) were collected. The genotypic diversity of L-type needles of Keteleeria fortunei was highest. The fungal diversity revealed by the two methods were compared. Most of the fungi revealed by the plating method were anamorphic taxa, while more teleomorphic genera were obtained by DGGE and sequence analyses.
The fungi revealed by DGGE were completely different to those revealed by the traditional culture-based methodology. This has important scientific implications in fungal ecology as well as studies of the diversity and functions of fungal endophytes. Culture-based methodology is appropriate to detect fast-growing fungi, which may have no biological significance. Studies on fungi associated with pine needle decay and fungal endophytes should therefore be re-evaluated, as the incorporation of DGGE appears to have nullified all previous research.
School:The University of Hong Kong
School Location:China - Hong Kong SAR
Source Type:Master's Thesis
Keywords:fungi china hong kong pinaceae
Date of Publication:01/01/2005