Showing papers by "Michael J. Wingfield published in 2006"
TL;DR: DNA sequence data of the 28S rDNA is employed to resolve apparent lineages within the Botryosphaeriaceae and 10 lineages are recognised, including an unresolved clade including species of Camarosporium/Microdiplodia.
700 citations
TL;DR: DNA sequence data from combined partial nuclear LSU and β-tubulin genes are used to consider the phylogenetic relationships of 50 Ophiostoma species, representing all the major morphological groups in the genus, and reveal additional lineages linked to morphological characters.
195 citations
TL;DR: Characteristics of the fungal growth on three different media, morphology of the anamorph and teleomorph structures as well as ascospore germination patterns were used to describe 21 new species of Mycosphaerella.
192 citations
TL;DR: Three new species of Botryosphaeria rhodina are described here as three new species L. venezuelensis sp.
Abstract: Botryosphaeria rhodina (anamorph Lasiodiplodia theobromae) is a common endophyte and opportunistic pathogen on more than 500 tree species in the tropics and subtropics. During routine disease surveys of plantations in Australia and Venezuela several isolates differing from L. theobromae were identified and subsequently characterized based upon morphology and ITS and EF1-alpha nucleotide sequences. These isolates grouped into three strongly supported clades related to but different from the known taxa, B. rhodina and L. gonubiensis, These have been described here as three new species L. venezuelensis sp. nov., L. crassispora sp. nov. and L. rubropurpurea sp. nov. The three could be distinguished easily from each other and the two described species of Lasiodiplodia, thus confirming phylogenetic separations. Furthermore all five Lasiodiplodia spp. now recognized separated from Diplodia spp. and Dothiorella spp. with 100% bootstrap support.
157 citations
TL;DR: Information is presented on the extent of fungal collections preserved at PREM, and the associated research publications that have largely resulted from this resource, to estimate the potential number of fungi that could be expected in South Africa.
119 citations
TL;DR: Cytospora spp.
Abstract: Cytospora spp. (anamorphs of Valsa spp.) are common inhabitants of woody plants and they include important stem and branch canker pathogens. Isolates of these fungi were collected from diseased and healthy trees in South Africa. They were identified based on morphology and DNA sequence homology of the intertransgenic spacer ribosomal DNA. South African isolates were compared with isolates collected in other parts of the world, and they represented 25 genetically distinct sequences residing within the populations of 13–14 known species and three unique lineages. Several species are new records for South Africa, doubling previous reports of these fungi from the country. Similarities between South African isolates of Cytospora from non-native Eucalyptus, Malus, Pinus, Populus, Prunus and Salix species and isolates from Australia, Europe or America suggest that the fungal pathogens were imported with their hosts as endophytes. Isolates from indigenous Olea and Acacia appear to represent native populations. Host shifts were evident, including populations on Eucalyptus that also occurred on Mangifera, Populus, Sequoia, Tibouchina and Vitex. Isolates related to Valsa kunzei represent the first report of a Cytospora species on the widely cultivated timber tree, Pinus radiata. An identification key to Cytospora species in South Africa is included.
103 citations
TL;DR: DNA sequences for three loci, ITS, Elongation factor 1-alpha (EF-1α) and Actin (ACT) were used to reconsider species boundaries for Mycosphaerella spp.
102 citations
TL;DR: Evidence is presented that the vascular wilt pathogen Ceratocystis fimbriata causes mango sudden decline disease in Oman, possibly in concert with Lasiodiplodia theobromae and the recently described Ceratocytestis omanensis.
Abstract: Mango sudden decline is a recently introduced, economically serious disease in Oman. Affected mango trees have wilting symptoms that usually begin on one side and later spread to involve the entire tree. Trees exude amber-coloured gum from the bark of their trunks or branches and vascular tissues are discoloured. Having entered Oman in the recent past, survey data is presented that shows the disease to have spread throughout the northern part of the country. Evidence is presented that the vascular wilt pathogen Ceratocystis fimbriata causes mango sudden decline disease in Oman, possibly in concert with Lasiodiplodia theobromae and the recently described Ceratocystis omanensis. Isolates of these fungi from affected trees, cause infection and can be recovered from inoculated seedlings. Bark beetles (Hypocryphalus mangiferae) are shown to carry C. fimbriata and L. theobromae and are presumably responsible for transmitting both pathogens to healthy mango trees. Acting as a wounding agent and vector, the bark beetle is likely to have assisted the rapid spread of the disease across Oman.
97 citations
TL;DR: Transmission electron-microscopic studies of the septal pores confirm that all three Quambalaria spp.
90 citations
TL;DR: Both phylogenetic data and morphological characteristics showed clearly that isolates of C. zuluensis represent at least two taxa, one of which was originally described from South Africa, and is newly described as C. gauchensis.
76 citations
TL;DR: Three non-native bark beetle species infest various Pinus species in South Africa, and they are known to carry at least 12 different species of ophiostomatoid fungi, some of which have not been identified to species level.
TL;DR: This is the first time a single-copy protein coding gene has been used to study phylogenetic relationships in Armillaria, and overall the data support previously held views regarding the relationships between species.
Abstract: Armillaria species are important root rot pathogens with a wide host range and a worldwide distribution. The taxonomy of these fungi has been problematic for many years but the understanding of the relationships between them has been substantially improved through the application of DNA sequence comparisons. In this study, relationships between different Armillaria species were determined using elongation factor 1-alpha DNA sequence data for the first time. A total of 42 isolates, representing the majority of Armillaria species, with diverse geographic distributions and hosts, were included in this study. PCR amplification yielded products of 600 bp for all the isolates. Phylogenetic trees resulting from parsimony analysis showed that this gene region is useful for studying relationships between species. Generally, results were similar to those emerging from previous comparisons using ITS and IGS-1 sequence data. Phylogenetic trees generated from the dataset grouped the African taxa in a strongly supported clade, basal to the rest of the Armillaria species included in the study. The Armillaria species originating from the Northern Hemisphere formed a monophyletic group. Within this group, isolates of A. mellea constituted four subclades, representing their geographical origin. The phylogenetic relationships among species from the Southern Hemisphere were not entirely resolved. However, A. pallidula, A. fumosa and A. hinnulea grouped in a strongly supported clade and isolates of A. limonea formed a sister clade with those of A. luteobubalina. This is the first time a single-copy protein coding gene has been used to study phylogenetic relationships in Armillaria, and overall the data support previously held views regarding the relationships between species.
TL;DR: Results show, for the first time, that C. cubensis occurs in Kenya, Malawi, and Mozambique on nonnative Eucalyptus spp.
Abstract: Chrysoporthe cubensis and C. austroafricana, collectively known as Cryphonectria cubensis in the past, are important canker pathogens of Eucalyptus spp. worldwide. Previous studies have suggested that Chrysoporthe austroafricana occurs only in South Africa, whereas C. cubensis occurs in Australia, Cameroon, Tanzania, Democratic Republic of Congo, Republic of Congo, Southeast Asia, and South, Central, and North America. In South Africa, C. austroafricana is a pathogen on nonnative Eucalyptus (Myrtaceae) and Tibouchina (Melastomataceae) spp., both residing in the order Myrtales. Recently, the fungus also has been found on native Syzygium cordatum trees in the country, leading to the hypothesis that it is native to Africa. In contrast, C. cubensis is thought to have been introduced into Africa and is known only on non-native Eucalyptus spp. and S. aromaticum (clove) in four countries. The aim of this study was to consider the distribution of Chrysoporthe spp. on non-native Eucalyptus spp. as well as on native Myrtales in southern and eastern Africa. Isolates were collected from as many trees as possible and characterized based on their morphology and DNA sequence data for two gene regions. Results show, for the first time, that C. cubensis occurs in Kenya, Malawi, and Mozambique on nonnative Eucalyptus spp. C. austroafricana was found for the first time in Mozambique, Malawi, and Zambia on non-native Eucalyptus spp. and native S. cordatum. The known distribution range of C. austroafricana within South Africa also was extended during these surveys.
TL;DR: The new family Cryphonectriaceae (Diaporthales) is defined to accommodate genera in the Cryph onectria-Endothia complex and can be distinguished from those in other families or undescribed groups of the Diaporthale by the formation of orange stromatic tissue at some stage of their life cycle.
Abstract: Recent phylogenetic studies on the members of the Diaporthales have shown that the order includes a number of distinct phylogenetic groups. These groups represent the Gnomoniaceae, Melanconidaceae, Valsaceae, Diaporthaceae and Togniniaceae. New groups representing undescribed families also have emerged and they have been referred to as the Schizoparme, Cryphonectria-Endothia and Harknessia complexes. In this study we define the new family Cryphonectriaceae (Diaporthales) to accommodate genera in the Cryphonectria-Endothia complex. These genera can be distinguished from those in other families or undescribed groups of the Diaporthales by the formation of orange stromatic tissue at some stage of their life cycle and a purple reaction in KOH and a yellow reaction in lactic acid associated with pigments in the stromatic tissue or in culture.
TL;DR: The genus Colletogloeopsis is emended to include species with pycnidial conidiomata, and the new combination Colletogsloeopsis zuluense is proposed to treat Eucalyptus canker disease.
01 Apr 2006-Food Additives and Contaminants Part A-chemistry Analysis Control Exposure & Risk Assessment
TL;DR: Mechanical dehulling methods significantly reduced fumonisin levels in maize, resulting in a mean reduction of 62% for Mini-PRL, 65% for Engelberg, and 57% for the attrition disc mill.
Abstract: Mechanical shelling and dehulling methods were tested to evaluate their impact on Fusarium infection and fumonisin contamination in maize. All shelling methods which were tested were found to damage the grains. The IITA sheller caused the highest level (up to 3.5%) of damage. Fusarium populations were higher on damaged grains, the highest being recorded from grains damaged by the IITA sheller (2,533.3 cfu g(-1)). Fumonisin levels were higher in damaged grains, the highest being in maize shelled with the IITA sheller (2.2 mg kg(-1)). Fumonisin levels were positively and significantly correlated with the percentage of damage caused by the shelling methods, and with the number of Fusarium colonies in maize. Mechanical dehulling methods significantly reduced fumonisin levels in maize, resulting in a mean reduction of 62% for Mini-PRL, 65% for Engelberg, and 57% for the attrition disc mill. It is important for farmers to choose appropriate shelling methods to reduce mycotoxin contamination. Dehulling should be widely promoted for the reduction of mycotoxins in maize.
TL;DR: This study represents the first report of Chr.
Abstract: Heath, R. N., Gryzenhout, M., Roux, J., and Wingfield, M. J. 2006. Discovery of the canker pathogen Chrysoporthe austroafricana on native Syzygium spp. in South Africa. Plant Dis. 90:433-438. Chrysoporthe canker is one of the most important diseases of plantation-grown Eucalyptus spp. in tropical and subtropical regions worldwide. For many years, the disease was reported to be caused by the fungal pathogen Cryphonectria cubensis. Recent DNA-based studies have shown that the fungus in South Africa is not conspecific with Chr. cubensis and it was recently described in the new genus Chrysoporthe as Chrysoporthe austroafricana. Chr. austroafricana is known only from South Africa, where it causes severe cankers on Eucalyptus spp. and on ornamental Tibouchina trees, both of which have been introduced into South Africa. The origin of Chr. austroafricana is unknown, but it is possible that it expanded its host range from native trees related to Eucalyptus and Tibouchina spp. to these exotic hosts. Subsequent surveys of some indigenous South African Myrtales led to the discovery of fruiting structures resembling those of Chr. austroafricana on native Syzygium cordatum and S. guineense. The fungus from these Syzygium spp. was identified as Chr. austroafricana based on morphological characteristics and β-tubulin gene sequences. Pathogenicity trials showed that Chr. austroafricana is more virulent on exotic Eucalyptus spp. than on native S. cordatum. This study represents the first report of Chr. austroafricana from native hosts in South Africa and adds credence to the view that the fungus could be native to this country. Additional keywords: Diaporthales, forestry, Myrtales
TL;DR: Molecular data suggest that adaptation to the Protea infructescence niche by Ophiostoma spp.
TL;DR: In this article, the authors used 10 microsatellite markers to investigate the population biology of Ophiostoma ips in native (Cuba, France, Morocco and USA) and non-native (Australia, Chile and South Africa) areas to characterize host specificity, reproductive behaviour, and the potential origin of the fungus and its insect vectors.
Abstract: Ophiostoma ips is a common fungal associate of various conifer-infesting bark beetles in their native ranges and has been introduced into non-native pine plantations in the Southern Hemisphere. In this study, we used 10 microsatellite markers to investigate the population biology of O. ips in native (Cuba, France, Morocco and USA) and non-native (Australia, Chile and South Africa) areas to characterize host specificity, reproductive behaviour, and the potential origin as well as patterns of spread of the fungus and its insect vectors. The markers resolved a total of 41 alleles and 75 haplotypes. Higher genetic diversity was found in the native populations than in the introduced populations. Based on the origin of the insect vectors, the populations of O. ips in Australia would be expected to reflect a North American origin, and those in Chile and South Africa to reflect a European origin. However, most alleles observed in the native European population were also found in the native North American population; only the allele frequencies among the populations varied. This admixture made it impossible to confirm the origin of the introduced Southern Hemisphere (SH) populations of O. ips . There was also no evidence for specificity of the fungus to particular bark beetle vectors or hosts. Although O. ips is thought to be mainly selffertilizing, evidence for recombination was found in the four native populations surveyed. The higher genetic diversity in the North American than in the European population suggests that North America could be the possible source region of O. ips.
TL;DR: Two new Fusicoccum species are characterized, isolated from Eucalyptus and Acacia trees in Venezuela, based on morphological features in culture and comparisons of DNA sequence data, which show that they are anamorphs of Botryosphaeria.
TL;DR: A new genus, Holocryphia, is erected for C. havanensis but reside in a genus distinct from Cryphonectria sensu stricto, which is described here as Microthia.
TL;DR: DNA sequence comparisons of isolates from Tibouchina lepidota in Colombia revealed that they represent a new sub-clade within the greater Chrysoporthe clade, described as Chrysoborthe inopina sp.
TL;DR: DNA data support the original generic concept of Truncatella, which encompasses Pestalotiopsis species having 3-septate conidia, and the genus Sarcostroma is retained as separate from Seimatosporium.
Journal Article•
TL;DR: The population diversity of 80 C. fimbriata isolates from Eucalyptus trees in South Africa showed a low gene diversity and the population was found to be predomi- nantly clonal, providing good evidence that the fungus has been introduced into South Africa.
Abstract: Ceratocystis fimbriata is one of the most important pathogens of woody plants in the world. This fungus is also a serious pathogen of Eucalyptus species in various countries and has recently been reported from wounds on these trees in South Africa. Inoculation studies have shown that the fungus can cause disease on Eucalyptus spp. in South Africa, although trees dying in the field due to infection have never been encountered. The origin of C. fimbriata in South Africa is unknown, but there is some phylogenetic evidence that the fungus has a Latin American origin. In this study, microsatellite markers specifically designed for C. fimbriata were used to analyse the population diversity of 80 C. fimbriata isolates from Eucalyptus trees in South Africa. Analyses showed a low gene diversity (H = 0.36) and the population was found to be predomi- nantly clonal (IA = 0.95, P < 0.0001). The genotypic diversity was high (GST = 0.99) and the maximum genotypic diversity was very low (1.23%). These data provide good evidence that C. fimbriata has been introduced into South Africa.
TL;DR: Celoporthe dispersa gen. et sp.
TL;DR: It is concluded that the Ceratocystis sp.
TL;DR: Nine polymorphic microsatellite markers for the phytopathogenic fungus Colletogloeopsis zuluensis, the causal agent of an important stem canker disease of Eucalyptus, were isolated and characterized and will be used to determine the population genetic structure of C. Zuluensis.
Abstract: Nine polymorphic microsatellite markers for the phytopathogenic fungus Colletogloeopsis zuluensis, the causal agent of an important stem canker disease of Eucalyptus, were isolated and characterized. Two methods, random amplified microsatellite sequences (RAMS) and fast isolation by AFLP of sequences containing repeats with modifications (M-FIASCO), were used to isolate the microsatellites. Primers for 28 prospective microsatellite regions were designed and nine of these were polymorphic for C. zuluensis. Allelic diversity ranged from 0.12 to 0.80 with a total of 37 alleles. These markers will be used in future to determine the population genetic structure of C. zuluensis isolates and to monitor their global movement.
TL;DR: This review represents a summary of the taxonomic changes to species of Cryphonectria sensu lato, and discusses the impact that these changes might have on the understanding of their ecology, pathology and worldwide distribution.
Abstract: Species of Cryphonectria include some of the world's most important and devastating tree pathogens. Largely through the application of DNA sequence phylogenies, the taxonomy of these fungi has undergone major changes in recent years. Cryphonectria, including the chestnut blight pathogen Cryphonectria parasitica, has been restricted to species that have semi-immersed stromata, orange and pulvinate conidiomata, and one-septate ascospores. Other species of Cryphonectria with different morphological characteristics have been transferred to new genera that are strongly supported by phylogenetic data. This review represents a summary of the taxonomic changes to species of Cryphonectria sensu lato, and we discuss the impact that these changes might have on the understanding of their ecology, pathology and worldwide distribution.
Journal Article•
TL;DR: Lesions associated with this disease are very characteristic, with chlorotic margins and masses of brown conidiophores occurring predominantly on the abaxial lesion surface, and results showed that the fungus represents an undescribed species of Pseudocercospora flavomarginata.
Abstract: Mycosphaerella represents one of the largest ascomycete genera accommodating more than 3000 names. Approximately 60 Mycosphaerella species have been linked to leaf diseases on Eucalyptus species, collectively known as Mycosphaerella Leaf Disease (MLD). Many hyphomycete and coelomycete anamorph genera are linked to Mycosphaerella and several species of the hyphomycete genus Pseudocercospora are associated with MLD symptoms on various Eucalyptus species. Eucalyptus trees in Vietnam and Thailand, particularly those of E. camaldulensis and hybrids of this species, commonly have a leaf spot disease caused by a species of Pseudocercospora. Lesions associated with this disease are very characteristic, with chlorotic margins and masses of brown conidiophores occurring predominantly on the abaxial lesion surface. The aim of this study was to characterise the Pseudocercospora species associated with this disease. This was achieved through studying the morphology of the fungus and via DNA sequence analysis from four nuclear gene regions. Results showed that the fungus represents an undescribed species of Pseudocercospora, that is formally described here as Pseudocercospora flavomarginata.
TL;DR: The aim of this study was to identify seven Armillaria isolates obtained from diseased tea bushes in Kenya using pectic enzyme profiles, PCR-RFLP and IGS-I DNA sequence data, and to suggest that this group is phylogenetically closely related to A. hinnulea from Australia and New Zealand.
Abstract: The aim of this study was to identify seven Armillaria isolates obtained from diseased tea bushes in Kenya using pectic enzyme profiles, PCR-RFLP and IGS-I DNA sequence data. The combination of these identification methods confirmed the presence of three distinct Armillaria groups. One of these groups resembled Zimbabwean group I (A. fuscipes). The second group was phylogenetically closely related to A. mellea ssp. nipponica. The third group was different from all other African isolates examined, but had isozyme patterns, especially of pectin methylesterases (PMEs), similar to those of isolates related to A. mellea ssp. nipponica. Analyses of sequence data suggested that this group is phylogenetically closely related to A. hinnulea from Australia and New Zealand.