Papers by Martin P. A. Coetzee
Armillaria using IGS-1 sequences and AFLP analysis. Fungal Diversity 34: 187-196.
Armillaria root-rot is one of the most serious root diseases of perennial tree crops in tropical ... more Armillaria root-rot is one of the most serious root diseases of perennial tree crops in tropical Africa. The disease was first reported on cacao in Ghana during 1927. It was initially referred to as 'collar crack' due to typical longitudinal cracks that are formed in the bark at the tree collar, as a result of mechanical pressure from fungal fans colonizing the cambium. These fungal fans are typical of species in the genus Armillaria. The pathogen associated with the disease was identified as A. mellea (Valh Ex. Fr.). However, A. mellea is a taxonomic complex that currently includes a number of morphologically indistinguishable species, the true identity of the species causing root-rot on cacao in Africa is thus uncertain. More recent studies have shown that DNA sequence comparisons can effectively differentiate among Armillaria species from Africa with uniform morphologies. In this study we applied a molecular approach to characterize Armillaria isolates associated with roo...
The present study aimed at evaluating the therapeutic properties of endemic Mascarene Aloes (A. p... more The present study aimed at evaluating the therapeutic properties of endemic Mascarene Aloes (A. purpurea Lam, A. tormentorii, A. lomatophylloides and A. macra Haw) and Aloe vera, extensively used in the traditional medicine. The antioxidant activity, cytotoxicity activity and neuroprotection properties relevant to neurodegenerative diseases were investigated. The free radical scavenging potential of the Aloes under study was evaluated using DPPH assay, and revealed that the 70 % (v/v) methanolic crude extracts of endemic Mascarene Aloes have potent radical scavenging properties. A. purpurea (Réunion Island) exhibited the highest radical scavenging potential, followed by A. macrum with an IC50 values of 0.334 mg/ml and 0.389 mg/ml respectively. In vitro cytotoxicity screening of crude methanolic extracts of the Aloes, using MTT cell proliferation assay indicated that the extracts of all the Aloes except A. macra elicited no toxic effect upon CAD neuronal cells at concentrations up to...
IMA Fungus, 2015
Jacaranda mimosifolia trees have been progressively dying due to Ganoderma root and butt rot dise... more Jacaranda mimosifolia trees have been progressively dying due to Ganoderma root and butt rot disease in Pretoria (the &amp;amp;amp;amp;amp;amp;quot;City of Jacarandas&amp;amp;amp;amp;amp;amp;quot;) for many years. Ganoderma austroafricanum was described from these trees previously but this was based on a single collection. This study treats a substantially expanded collection of isolates of Ganoderma made from all dying trees where basidiomes were present in a Pretoria suburb. DNA sequences were obtained from the ITS and LSU region for the isolates and compared against sequences on GenBank. Phylogenetic analyses were used to compare sequences with those for other Ganoderma species. Based on sequence comparisons and morphological characters, two new Ganoderma species were discovered and these are described here as G. enigmaticum and G. destructans spp. nov. Interestingly, the previously described G. austroafricanum was not found, G. enigmaticum was found on only one Ceratonia siliqua tree and G. destructans was found on all other trees sampled. The latter species appears to be the primary cause of root rot of J. mimosifolia in the area sampled.
Mycoscience, 2015
ABSTRACT Fourteen Chinese Biological Species (CBS) of Armillaria were previously identified in a ... more ABSTRACT Fourteen Chinese Biological Species (CBS) of Armillaria were previously identified in a collection of Chinese isolates. CBS C, F, G, H, J, L, N and O remained unnamed, while the remaining isolates included A. borealis, A. cepistipes, A. gallica, A. mellea, A. sinapina and A. tabescens. CBS F was suggested to represent A. singula based on basidiocarp morphology. In this study, phylogenetic relationships between Chinese Armillaria isolates and those from other parts of the world were determined based on DNA sequence data. Results of this study suggest that CBS F might not represent A. singula, and that A. monadelpha (a name applied to the North American form of A. tabescens by some authors) and A. tabescens should be treated as a single species. Four main phylogenetic lineages, referred to as the A. ostoyae, A. gallica, A. tabescens and A. mellea clusters, were identified on the phylogenetic trees. The unnamed biological species grouped within the “A. gallica cluster” and were phylogenetically closely related. The results of this study contribute to our current understanding of the systematics of Armillaria from South East Asia where these fungi are relatively poorly known.
Plant Pathology, 2005
Armillaria root rot is a serious disease in fir and mixed conifer forests of Bhutan, Eastern Hima... more Armillaria root rot is a serious disease in fir and mixed conifer forests of Bhutan, Eastern Himalayas. The species causing this disease have, however, never been identified. The aim of this study was to identify field isolates collected at four localities in Bhutan. Identification was based on RFLP analysis of the IGS-1 region, comparisons of ITS and IGS-1 sequence data with those available on GenBank, cladistic analyses and sexual compatibility studies. Isolates were found to reside in two distinct RFLP groups. RFLP group 1 isolates from Pinus wallichiana at Yusipang had RFLP profiles and IGS-1 sequences similar to those of Armillaria mellea ssp. nipponica . Although ITS sequence data are not available for A. mellea ssp. nipponica , sequences from this DNA region were most similar to the closely related A. mellea from Asia. The RFLP profile and IGS-1 sequences for RFLP group 2 isolates from Abies densa at Changaphug, Tsuga dumosa at Chimithanka as well as Picea spinulosa and T. dumosa in the Phobjikha valley were similar to those published for Armillaria borealis , Armillaria cepistipes , Armillaria gemina and Armillaria ostoyae . Distance analysis based on IGS-1 and ITS sequence data indicated that these isolates are closely related to A. cepistipes , Armillaria gallica and Armillaria sinapina . The isolates were, however, sexually incompatible with tester strains of A. cepistipes , A. gallica and A. sinapina . Although closely related to these species, they appear to represent a distinct taxon that will be referred to as Bhutanese phylogenetic species I (BPS I) until basidiocarps are found and the species can be described.
Plant Disease, 2005
ABSTRACT Erythricium salmonicolor causes a canker and die-back disease, commonly known as pink di... more ABSTRACT Erythricium salmonicolor causes a canker and die-back disease, commonly known as pink disease, on many tree species. During an investigation of diseases of Podocarpus henkellii and P. latifolius in the Mpumalanga Province of South Africa, typical symptoms of pink disease were observed on the branches of these trees. Stem and branch cankers covered with cracked bark and abundant pink mycelial growth were common on the affected trees. In subsequent surveys, the disease was also found on native Dais cotonifolia in the same area, as well as on native Ekebergia capensis and Maesa lanceolata in the KwaZulu-Natal Midlands. Phylogenetic analyses of ribosomal large subunit DNA sequence data were used to confirm the identity of the pathogen and obtain an indication of its phylogenetic placement within the Homobasidiomycetes. Isolates from all the native hosts recorded in this study, as well as from exotic Eucalyptus sp. and Acacia mearnsii, formed a strongly supported clade together with isolates from other parts of the world. Results confirmed that the pathogen in South Africa is Erythricium salmonicolor. Isolates from South Africa and Ethiopia grouped closely together, slightly different from E. salmonicolor isolates from the rest of the world. Our data also suggest that the genus name for E. salmonicolor possibly should be reconsidered because it groups separately from E. laetum or Corticium roseum. Phylogenetic analyses further indicated that the genus Erythricium is most closely related to Marchandiomyces aurantiacus, M. lignicola, C. roseum, E. laetum, Dendrothele maculata, D. roseacarneum, Vuilleminia comedens, V macrospora, Punctularia strigoso-zonata and Galzinia incrustans. These genera form a separate subclade, the corticioid clade, within the Homobasidiomycetes. Pink disease is potentially important in South Africa because it affects a wide range of native and exotic tree species, and this study provides a foundation for further research.
Mycologia, 2010
The taxonomy of Armillaria in southern South America has received little attention since the work... more The taxonomy of Armillaria in southern South America has received little attention since the work of Singer and others. In this study we examine the morphological traits and cultural features for taxa representing the lineages revealed based on molecular phylogeny, and we link them to previously described taxa based on morphology. Lineages I-IV were identified as Armillaria novae-zelandiae, A. montagnei, A. umbrinobrunnea comb. nov. and A. sparrei respectively. They could be differentiated morphologically based on dimension, features of the epicutis, annulus, stipe, hymenophoral trama and flavor and characteristics in culture. Furthermore there was no evidence of host preference for the species recognized. This is the first study integrating the phylogeny and morphology of Armillaria species from Patagonia, and it provides a foundation for future research on these fungi in South America.
Fungal Biology, 2013
Ceratocystis fimbriata sensu lato represents a complex of cryptic and commonly plant pathogenic s... more Ceratocystis fimbriata sensu lato represents a complex of cryptic and commonly plant pathogenic species that are morphologically similar. Species in this complex have been described using morphological characteristics, intersterility tests and phylogenetics. Microsatellite markers have been useful to study the population structure and origin of some species in the complex. In this study we sequenced the genome of C. fimbriata. This provided an opportunity to mine the genome for microsatellites, to develop new microsatellite markers, and map previously developed markers onto the genome. Over 6000 microsatellites were identified in the genome and their abundance and distribution was determined. Ceratocystis fimbriata has a medium level of microsatellite density and slightly smaller genome when compared with other fungi for which similar microsatellite analyses have been performed. This is the first report of a microsatellite analysis conducted on a genome sequence of a fungal species in the order Microascales. Forty-seven microsatellite markers have been published for population genetic studies, of which 35 could be mapped onto the C. fimbriata genome sequence. We developed an additional ten microsatellite markers within putative genes to differentiate between species in the C. fimbriata s.l. complex. These markers were used to distinguish between 12 species in the complex.
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Papers by Martin P. A. Coetzee