90 research outputs found
Taxonomy and phylogeny of Cryphonectria and allied genera
This thesis represents a critical taxonomical review of the fungal genus Cryphonectria sensu lato. An appropriate taxonomy for this group is of great importance because it includes many well known tree pathogens such as the chestnut blight fungus Cryphonectria parasitica and the Eucalyptus canker pathogen Cryphonectria cubensis. The many taxonomic changes introduced in studies presented in this thesis have largely arisen as a result of DNA sequence comparisons for Cryphonectria spp. that show that Cryphonectria sensu lato is comprised of different lineages, strongly supported by robust morphological characteristics. New taxa, of which many are pathogenic, have also been discovered. The expanded number of species of Cryphonectria and related genera as well as the consideration of large numbers of isolates has furthermore made it possible to establish a broad view of the group at the super-generic level. The first part of the thesis deals with studies on Cryphonectria cubensis. A new genus Chrysoporthe is described for C. cubensis sensu lato. Two additional species are also described for phylogenetic sub-clades previously known as C. cubensis. These include Chrysoporthe austroafricana, representing all isolates from South Africa, and an anamorphic species described in the new genus Chrysoporthella as Chrysop. hodgesiana, which is currently only known from Colombia on native Tibouchina spp. Isolate collections from several new host genera for Chr. cubensis are also characterized. Collections from Eucalyptus in Cuba, now representing the epitype of Chr. cubensis, also define the type of Chr. cubensis as residing in the South American sub-clade. Another new species, Chrysoporthe inopima from Tibouchina lepidota in Colombia is described as well as a new species Chrysoporthe doradensis for isolates from Eucalyptus spp. in Ecuador. A new family Cryphonectriaceae is described in this thesis for Cryphonectria, Chrysoporthe and Endothia. Genera in this family are united by orange stromatic tissue, with the pigments colouring purple in 3% KOH and yellow in lactic acid. The existence of this new family confirms the close relationship of Cryphonectria and morphologically similar genera. A proposal to conserve the name Cryphonectria against the new type C. parasitica is presented. This is required because Cryphonectria gyrosa, the currently accepted type, was erroneously used as type. The conservation of Cryphonectria against C. parasitica made it possible to describe the new genus Amphilogia for C. gyrosa. Amphilogia also includes a second species from New Zealand described as Amphilogia major, although no isolates currently exist for this species. New genera for existing Cryphonectria spp., as well as newly discovered fungi are presented in this thesis. The new genus Rostraureum is established for a fungus pathogenic on Terminalia ivorensis in Ecuador. This fungus also represents a new species, Rostraureum tropicale. Cryphonectria longirostris, originating from Puerto Rico, Trinidad and Tabago, is also transferred to Rostraureum. A fungus morphologically similar to Chrysoporthe on native Tibouchina, Miconia and exotic Eucalyptus spp. in Colombia, is described as Aurapex penicillata gen. sp. nov. Cryphonectria havanensis is transferred to the new genus Microthia. Cryphonectria coccolobae also resides in this genus based on morphology, although its phylogenetic relationship to C. havanensis could not be confirmed due the absence of isolates. A new fungus was discovered during surveys for C. coccolobae on Coccoloba uvifera in Florida, which is described in the new genus Ursicollum as U. fallax. Phylogenetic analyses in this study also clearly distinguish Cryphonectria eucalypti from Cryphonectria, and this fungus is thus transferred to the new genus Holocryphia. A minireview is presented at the end of the thesis and discusses the new taxonomic concepts developed for Cryphonectria during this thesis, and recent studies by other authors. The review describes how this new taxonomic scheme has changed our view and understanding of the distribution and ecology of Cryphonectria sensu stricto from what it has traditionally been seen. The final part of the thesis is written in the form of a monograph. It contains background information of all the species, including many pathogens, currently known in Cryphonectria and allied genera. The majority of these have recently been described, some in this thesis, and this chapter thus contains all recent information pertaining to them. It is intended that this monograph should be useful as a manual, enabling users to work with and isolate these fungi and to identify the different taxa based on morphology and phylogenetic relationships. The studies presented in this thesis greatly change the taxonomy of Cryphonectria sensu lato, which is now seen as representing a large number of genera and species in a new family. Many would argue that Cryphonectria is still monophyletic, but the different lineages shown by DNA sequence comparisons are morphologically inordinately diverse, and clearly represent different genera. Studies presented in this thesis further suggest that additional genera await description from diverse geographical areas and ecological niches. The studies presented in this thesis will hopefully provide a foundation against which these new taxa can be compared and will improve our understanding of tree diseases.Thesis (PhD)--University of Pretoria, 2009.Microbiology and Plant PathologyUnrestricte
New and rare coelomycetes with appendage-bearing conidia from Pondoland, South Africa
During a mycological excursion to the Pondoland region of South Africa in
2008, six interesting anamorphic fungi with appendage-bearing conidia were isolated.
They are Bartalinia pondoensis, Crucellisporium umtamvunae, and Mycohypallage
margaretae, all of which are new to science, Mycohypallage congesta with a new
observation of gelatinous basal appendage, Mycotribulus mirabilis on a new host plant,
Apodytes, and Chaetospermum camelliae. Morphological characters are described
and notes provided. The teleomorphic affinity of C. umtamvunae to the Helotiales is
proposed based on DNA sequence data.http://www.mycotaxon.com
Five new species of the Botryosphaeriaceae from Acacia karroo in South Africa
The Botryosphaeriaceae represents an important, cosmopolitan family
of latent pathogens infecting woody plants. Recent studies on native trees in southern
Africa have revealed an extensive diversity of species of Botryosphaeriaceae, about
half of which have not been previously described. This study adds to this growing
body of knowledge, by discovering five new species of the Botryosphaeriaceae on
Acacia karroo, a commonly occurring native tree in southern Africa. These species
were isolated from both healthy and diseased tissues, suggesting they could be latent
pathogens. The isolates were characterized based on their morphology and compared
to other species for which DNA sequence data are available, in phylogenetic analyses
based on the ITS, TEF-1α, β-tubulin and LSU gene regions. The five new species
were described as Diplodia allocellula, Dothiorella dulcispinae, Do. brevicollis,
Spencermartinsia pretoriensis and Tiarosporella urbis-rosarum. Evidence emerging
from this study suggests that many more species of the Botryosphaeriaceae remain to
be discovered in the southern Africa.Members of the Tree Protection Cooperative Programme (TPCP), the DST/NRF Centre of Excellence in Tree Health Biotechnology (CTHB) and the University of Pretoria, South Africa.http://www.cryptogamie.com/pagint_en/recherche/affich_sommaire.php?cnumero=65hb201
Celoporthe dispersa gen. et sp. nov. from native Myrtales in South Africa
In a survey for Cryphonectria and Chrysoporthe species on
Myrtales in South Africa, a fungus resembling the stem canker
pathogen Chrysoporthe austroafricana was collected from native
Syzygium cordatum near Tzaneen (Limpopo Province), Heteropyxis
canescens near Lydenburg (Mpumalanga Province) and exotic Tibouchina
granulosa in Durban (KwaZulu-Natal Province). The fungus was associated
with dying branches and stems on S. cordatum, H.
canescens and T. granulosa. However, morphological
differences were detected between the unknown fungus from these three hosts
and known species of Chrysoporthe. The aim of this study was to
characterise the fungus using DNA sequence comparisons and morphological
features. Pathogenicity tests were also conducted to assess its virulence on
Eucalyptus (ZG 14 clones), H. natalensis and T.
granulosa. Plants of H. canescens were not available for
inoculation. Results showed distinct morphological differences between the
unknown fungus and Chrysoporthe spp. Phylogenetic analysis showed
that isolates reside in a clade separate from Chrysoporthe and other
related genera. Celoporthe dispersa gen. et sp. nov. is, therefore,
described to accommodate this fungus. Pathogenicity tests showed that
C. dispersa is not pathogenic to H.
natalensis, but that it is a potential pathogen of
Eucalyptus and Tibouchina spp
Population structure of Chrysoporthe austroafricana in southern Africa determined using Vegetative Compatibility Groups (VCGs)
Chrysoporthe austroafricana is one of the most damaging pathogens of Eucalyptus
trees in southern Africa. It also occurs on non-native Tibouchina granulosa trees and native
Syzygium species. Additional isolates of the pathogen from previously unstudied countries in
the region have become available from survey studies. The aim of this study was to use
VCGs to consider the diversity in populations of isolates collected in various countries in
southern Africa (Malawi, Mozambique, Namibia, South Africa and Zambia) and from
different hosts. We also wanted to determine whether there are shared VCGs among these
countries and hosts in southern Africa and establish a VCG tester strain data base. Results
showed a high diversity amongst isolates from different countries and hosts, but suggested
little movement of VCGs among countries or hosts based on the available isolates. A total of
108 VCG tester strains were identified for southern Africa.The University of Pretoria (UP), National Research Foundation (NRF), Forestry and Agricultural Biotechnology Institute (FABI) and Tree Protection Cooperative Program (TPCP).http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1439-0329hb2016Microbiology and Plant Patholog
Botryosphaeriaceae species overlap on four unrelated, native South African hosts
Botryosphaeriaceae represents an important and diverse family of latent fungal pathogens of
woody plants. We address the question of host range of these fungi by sampling leaves and
branches of four native South African trees, including Acacia karroo (Fabaceae), Celtis africana
(Cannabaceae), Searsia lancea (Anacardiaceae), and Gymnosporia buxifolia (Celastraceae).Twonew
species of the Botryosphaeriaceae, namely Tiarosporella africana sp. nov. and Aplosporella javeedii
sp. nov. were identified, together with fiveknown species, including Neofusicoccum parvum,
Neofusicoccum kwambonambiense, Spencermartinsia viticola, Diplodia pseudoseriata, and Botryosphaeria
dothidea. Most Botryosphaeriaceae occurred on more than one host. With the exception
of S. lancea, which was infected by A. javeedii all the hosts were infected by more than one Botryosphaeriaceae
species. Collectively, the results suggest that some intrinsic host factors,
possibly combined with local environmental conditions, affect the distribution and co-infectivity
of various hosts by the Botryosphaeriaceae. This would counteract the general ability of
a species in the Botryosphaeriaceae to infect a broad range of plants. The combination of host
and environmental factors might also explain why some Botryosphaeriaceae with apparently
broad host ranges, are found on different suites of hosts in different areas of the world.Tree Protection Cooperative Programme (TPCP), the DST/NRF Centre of Excellence in Tree Health Biotechnology (CTHB) and the University of Pretoria, South Africa.http://www.elsevier.com/locate/funbiohb201
Microthia, Holocryphia and Ursicollum, three new genera on Eucalyptus and Coccoloba for fungi previously known as Cryphonectria
Cryphonectria havanensis is a fungus associated with
Eucalyptus species in Cuba and Florida (U.S.A.). Until recently,
there have been no living cultures of C. havanensis and it has thus
not been possible to assess its taxonomic status. Isolates thought to
represent this fungus have, however, emerged from surveys of
Eucalyptus in Mexico and Hawaii (U.S.A.). Results of this study
showed that these isolates represent C. havanensis but reside in a
genus distinct from Cryphonectria sensu stricto, which is described
here as Microthia. Isolates of an unidentified fungus occurring on
Myrica faya in the Azores and Madeira also grouped in
Microthia and were identical to other M. havanensis
isolates. Cryphonectria coccolobae, a fungus occurring on sea grape
(Coccoloba uvifera) in Bermuda and Florida, was found to be
morphologically identical to Microthia and is transferred to this
genus, but as a distinct species. Surveys for M. coccolobae on sea
grape in Florida, yielded a second diaporthalean fungus from this host. This
fungus is morphologically and phylogenetically distinct from M.
coccolobae and other closely related taxa and is described as
Ursicollum fallax gen. et sp. nov. Phylogenetic analyses in this
study have also shown that isolates of C. eucalypti, a pathogen of
Eucalyptus in South Africa and Australia, group in a clade separate
from all other groups including that representing Cryphonectria sensu
stricto. This difference is supported by the fact that Cryphonectria
eucalypti has ascospore septation different to that of all other
Cryphonectria species. A new genus, Holocryphia, is thus
erected for C. eucalypti
Endophyte isolations from Syzygium cordatum and a Eucalyptus clone (Myrtaceae) reveal new host and geographical reports for the Mycosphaerellaceae and Teratosphaeriaceae
Speci e s of Mycosphaerellaceae and
Teratosphaeriaceae (Ascomycetes) cause important leaf, shoot
and canker diseases globally on a broad range of hosts, including
Eucalyptus and other Myrtaceae. Recently, species of
the Mycosphaerellaceae and Teratosphaeriaceae have been
isolated as asymptomatic endophytes. In this study, endophytic
species of Mycosphaerellaceae and Teratosphaeriaceae
were isolated from samples taken from healthy native
Syzygium cordatum (Myrtaceae) and related non-native Eucalyptus
grandis x E. camaldulensis (hybrid clone) growing in
Mtubatuba, KwaZulu Natal, South Africa. Multi-locus sequence
analysis (MLSA) using the Internal Transcribed Spacer
(ITS) region, the partial Large Subunit (LSU; 28S nrDNA)
of the nuclear ribosomal DNA operon and Translation Elongation
Factor-1α (TEF-1α) genes were used to correctly
identify the 22 resulting isolates. The isolates grouped in five
clades representing Readeriella considenianae that was isolated
only from the Eucalyptus hybrid clone, Mycosphaerella
marksii and M. vietnamensis from S. cordatum and
Pseudocercospora crystallina from both S. cordatum and the
Eucalyptus hybrid clone. Interestingly, the serious canker
pathogen T. zuluensis was isolated from Eucalyptus leaves,
although it is known only from stem and branch cankers. Of
the species found, R. considenianae and M. vietnamensis were
found in South Africa for the first time, while M. marksii,
M. vietnamensis and P. crystallina were shown to naturally
infect native S. cordatum for the first time. Despite the limited number of trees sampled, the new host and distribution reports
show that more intensive sampling, especially following an
endophyte approach, will reveal more complete patterns of
host preference and geographical distribution for these fungi.Thutuka Funding programme of the National Research Foundation (NRF), members of the Tree Protection Co-operative Programme (TPCP) and the Department of Science and
Technology (DST)/NRF Centre of Excellence in Tree Health Biotechnology (CTHB), South Africa.http://link.springer.com/journal/13313hb201
Species delineation in the tree pathogen genus Celoporthe (Cryphonectriaceae) in southern Africa
The genus Celoporthe was first described
when C. dispersa was discovered in South Africa
associated with dieback and cankers on trees in the
Myrtales. Four additional species were recently
described from Eucalyptus and Syzygium cumini in
China as well as S. aromaticum and Eucalyptus in
Indonesia. Inoculation trials have shown that all
Celoporthe species, including those that have not been
found on Eucalyptus species in nature, are pathogenic
to Eucalyptus and they are thus potentially threatening
to commercial Eucalyptus forestry. New isolates,
morphologically similar to Celoporthe, have been
collected from S. legatti in South Africa and S.
guineense in Zambia. Multigene phylogenetic analyses
based on DNA sequences of the ITS region, TEF1a
gene and two areas of the b-tubulin gene revealed
additional cryptic species in Celoporthe. Phylogenetic
data were supported by morphological differences.
These resulted in the description of two previously
unknown species of Celoporthe, namely C. fontana and
C. woodiana, for two of these cryptic groups, while the
third group represented C. dispersa. These species all
can readily infect Eucalyptus as well as several species
of Syzygium, the latter of which are native to Africa.We thank the University of Pretoria (UP), National
Research Foundation (NRF), Forestry and Agricultural
Biotechnology Institute (FABI) and Tree Protection Cooperative
Program (TPCP) for financial support.http://www.mycologia.org/am201
Multiple Phytophthora species associated with a single riparian ecosystem in South Africa
The diversity of Phytophthora spp. in rivers
and riparian ecosystems has received considerable
international attention, although little such research
has been conducted in South Africa. This study
determined the diversity of Phytophthora spp. within
a single river in Gauteng province of South Africa.
Samples were collected over 1 y including biweekly
river baiting with Rhododendron indicum leaves.
Phytophthora isolates were identified with phylogenetic
analyses of sequences for the internal transcribed
spacer (ITS) region of the ribosomal DNA and the
mitochondrial cytochrome oxidase c subunit I (coxI)
gene. Eight Phytophthora spp. were identified, including
a new taxon, P. taxon Sisulu-river, and two
hybrid species from Cooke’s ITS clade 6. Of these,
species from Clade 6 were the most abundant,
including P. chlamydospora and P. lacustris. Species
residing in Clade 2 also were encountered, including
P. multivora, P. plurivora and P. citrophthora. The
detection of eight species in this investigation of
Phytophthora diversity in a single riparian river
ecosystem in northern South Africa adds to the
known diversity of this genus in South Africa and
globally.We further acknowledge financial support
from the National Research Foundation (NRF), the
Department of Science and Technology/National Research
Foundation (DST/NRF) Centre of Excellence in Tree
Health Biotechnology (CTHB) and the University of
Pretoria, South Africa.http://www.mycologia.orgam2016Forestry and Agricultural Biotechnology Institute (FABI)Genetic
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