1,294 research outputs found
Cassie Martin, Clara Bates Wingfield, and Tommy Zachery, ca. 1940s
No full text(L-r) Cassie Martin, Clara Bates Wingfield, and Tommy Zachery, ca. 1940sCassie Martin, Clara Bates Wingfield, and Tommy Zachery, ca. 1940
Multigene phylogeny and mating tests reveal three cryptic species related to Calonectria pauciramosa
No full textCalonectria pauciramosa is a pathogen of numerous plant hosts worldwide. Recent studies have indicated that it included cryptic species, some of which are identified in this study. Isolates from various geographical origins were collected and compared based on morphology, DNA sequence data of the ß-tubulin, histone H3 and translation elongation factor-1 regions and mating compatibility. Comparisons of the DNA sequence data and mating compatibility revealed three new species. These included Ca. colombiana sp. nov. from Colombia, Ca. polizzii sp. nov. from Italy and Ca. zuluensis sp. nov. from South Africa, all of which had distinguishing morphological features. Based on DNA sequence data, Ca. brasiliensis is also elevated to species leve
Distribution of Diplodia pinea and its genotypic diversity within asymptomatic Pinus patula trees
No full textDiplodia pinea (= Sphaeropsis sapinea) is an endophytic fungus and opportunistic canker pathogen of Pinus spp. The diversity of this fungus has been studied at broad geographic scales, but little is known regarding its population structure at smaller spatial scales such as within a single tree. This is despite the importance that diversity in a single tree might hold for understanding the biology of the fungus, especially the role of the endophytic or asymptomatic phase in disease development. Moreover there was not information regarding the distribution of the fungus within healthy trees and its persistence. The genotypic diversity of these isolates was investigated using microsatellite markers. Five polymorphic markers were developed and these were used together with eight previously developed markers and vegetative compatibility tests to study the genotypic diversity of D. pinea isolates. In this study, D. pinea was isolated for the first time in the well structured stems of healthy P. patula trees along with branches and cones. From a total of 44 isolates collected from five trees, 39 microsatellite haplotypes and 32 vegetative compatibility groups (VCG's) were identified. The results indicate high genotypic diversity of D. pinea within individual asymptomatic trees which will lead to disease outbreak when trees are physiologically stressed
High intercontinental migration rates and population admixture in the sapstain fungus Ophiostoma ips
No full textOphiostoma 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 self-fertilizing, 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
Comparison of three varieties of Leptographium wageneri using Random Amplified Polymorphic DNA
No full textLeptographium wageneri (Kendrick) Wingfield is the cause of black stain root disease in western North America. The fungus has been separated into three host-specialised morphological variants, namely L. wageneri var. wageneri (Kendrick) Wingfield, var. pseudotsugae Harrington & Cobb and var. ponderosum (Harrington & Cobb) Harrington & Cobb. These varieties have been well-characterised on the basis of both morphological and molecular data. The aim of this study was to determine whether HAPD analysis might be used in distinguishing between the three varieties of L. wageneri. Screening was performed for thirty primers, and four primers that produced unique DNA fingerprints for each variety were selected. RAPD analysis separated the three varieties of L. wageneri into distinct groups. The RAPD analysis was reliable, reproducible and might be useful in separating the three varieties of L. wageneri, which are morphologically very similar
Calonectria species associated with cutting rot of Eucalyptus
No full textDecline in the productivity of Eucalyptus hybrid cutting production in the Guangdong Province of China is linked to cutting rot associated with several Calonectria spp. The aim of this study was to identify these fungi using morphological and DNA sequence comparisons. Two previously undescribed Calonectria spp., Ca. pseudoreteaudii sp. nov. and Ca. cerciana sp. nov. were identified together with Ca. pauciramosa. Calonectria pseudoreteaudii resides in the Ca. reteaudii complex and Ca. cerciana is closely related to Ca. morganii. Connected to the discovery of Ca. pseudoreteaudii, species in the Ca. reteaudii complex were re-considered and the group is shown to accommodate two cryptic species. These originate from Australia and are described as Ca. queenslandica sp. nov. and Ca. terrae-reginae sp. nov
DNA sequence incongruence and inconsistent morphology obscure species boundaries in the Teratosphaeria suttonii species complex
No full textTeratosphaeria suttonii (=Kirramyces epicoccoides) is a leaf pathogen that can cause premature defoliation, reduced growth and vigor, and subsequent tree death of many Eucalyptus species. Although the fungus primarily infects mature leaves in the lower canopy, infections can spread to younger leaves during continued epidemics or when trees are stressed. Teratosphaeria suttonii has a wide distribution in Australia and has been introduced to many other parts of the world, most probably with germplasm used to establish plantations. The aim of this study was to establish the phylogenetic relationships between T. suttonii isolates from different countries and to consider whether cryptic species exist in a species complex. DNA from parts of the nuclear ribosomal internal transcribed spacer, beta-tubulin, and elongation factor-1 alpha genes was sequenced and analyzed for isolates from throughout the range of T. suttonii in Australia, and from six countries (China, Indonesia, South Africa, Uruguay, United States, and Vietnam) where the pathogen is introduced. Morphometrics of conidia produced both in vivo and in vitro were also considered. Analysis of the sequence data resulted in incongruent genealogies. Furthermore, groups of isolates in the genealogies could not be linked to area of origin. Similarly, differences in conidial morphology could not be linked to any of the phylogenetic groups. There was no evidence of distinct species boundaries, and isolates from Australia were closely related to those from other parts of the world. The results of this study support the treatment of T. suttonii as a morphologically and genetically diverse species in its natural range in Australia. The diversity is reflected in introduced populations
Names of fungal species with the same epithet applied to different morphs: how to treat them
No full textThe abolition of the separate naming of different morphs of the same fungal species in 2011 will inevitably result in many name changes in some genera. The working practices commended here are intended to minimize one category of these changes, that which can arise as a consequence of an author using the epithet of an asexual morph when describing the sexual morph of the same species. We consider that name proposed for the sexual morph in such cases should be treated as a formal error for a new combination and not as a new species, and so be corrected. This is interpreted as applying even where the author indicated that a new species was being described and designated a type. We argue that those formalities were a result of the requirements of the rules then in force, as the author recognized that a morph of a named species was being described, and not a new hitherto unnamed species was being reported - but was barred from making a new combination so used the same epithet for the new morph name instead. Where a type with the sexual morph was designated for the sexual morph, under this interpretation that no longer has nomenclatural status, the type being that of the basionym. The material for the sexual morph indicated as a type, would be available for designation as an epitype, though a modern sequenced sample with both sexual and asexual morphs would be more informative as an epitype in many cases. A proposal to regularize the working practice commended here, and also the converse situation where the sexual morph typified name is the earlier, will be made to the 2017 Shenzhen Congress
Diverse sources of infection and cryptic recombination revealed in South African Diplodia pinea populations
No full textThis study considers the population diversity and structure of Diplodia pinea in South Africa at different spatial scales from single trees to plantations, as well as comparing infections on healthy and diseased trees. A total of 236 isolates were characterized using 13 microsatellite markers. Analysis of these markers confirmed previous results that D. pinea has a high level of gene and genotypic diversity in South Africa, with the latter values ranging from 6. % to 68. % for the different plantations. The data also reflect a fungus with randomly associated alleles in populations at local plantation scales and for the population as a whole. These results suggest that recombination is occurring in D. pinea and that it most likely has a cryptic sexual state. The study also reveals the sources of endophytic infection and stress related disease out-breaks as diverse infections that have occurred over a long time period. In contrast, wound-associated die-back appears to be caused by clones of the pathogen occurring in narrow time frames
A pilot study to assess the possible methods of determining the burden of obstructive sleep apnoea syndrome in primary care
No full textCopyright © 2005 General Practice Airways Group Published by Elsevier Ltd.E.L. Palmer, D. Wingfield, K. Jamrozik and M.R. Partridgehttp://www.sciencedirect.com/science/journal/1471441
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