摘要:

Pure research is defined as experimental or theoretical work undertaken primarily to acquire new knowledge without any particular application or use in view. By contrast, applied research, which, of course, is also undertaken to acquire new knowledge, is directed primarily towards practical aims or objectives. In recent years governments worldwide have used Technology Foresight Exercises, to enable them to direct basic research in universities towards areas of science with commercial potential. There is, of course, but a short step between this approach and the direct involvement of universities in applied research. Using examples from four areas of research in mycology, this article advocates the need to maintain a broad base of pure (curiosity-driven) research in universities and research institutes, as well as identifying a need for government to provide additional funding for areas of research perceived to be of national importance.Key words: fungal diversity,Fusarium graminearum, protein production, Quorn® mycoprotein,Schizosaccharomyces pombe, technology foresight.

ISSN:0008-4026    

DOI:10.1139/b95-219

出版商:NRC Research Press    

年代:1995

数据来源: NRC

摘要:

The various difficulties in recording macromycetes and assessing their diversity are given and explored based on both temperate and tropical information. The importance of the tropical situation is emphasized but five steps are suggested by which some headway can be made. The ability of switching hosts by ectomycorrhizal fungi is emphasized.Key words: climate, fruiting, host switching, recording, succession, systematics.

ISSN:0008-4026    

DOI:10.1139/b95-220

出版商:NRC Research Press    

年代:1995

数据来源: NRC

摘要:

Measures of diversity depend on an eclectic taxonomy now being developed from comparisons of morphology, developmental programs, carbohydrate chemistry, fatty acids, and nucleotide sequences in a wide range of arbuscular fungal taxa obtained from living culture collections. Developmental patterns in character origin and transformation are providing clues of intrinsic causation in evolution of diversity. Extrinsic causation is being identified from population-level dynamics, as well as data on species numbers, abundance, composition, and distribution. Detection of species is based solely on sporulation, so that a combination of field sampling and various trap culture methods provide a more comprehensive estimate of fungal community organization. Species distributions rarely correlate with ecological gradients or hypothesized phylogenetic relationships, suggesting that an important causal factor of present-day distributions is dispersal over geologic time. Global distribution of both derived and ancestral species and representation of all genera in most plant root systems further indicate that local diversity has a strong historical component, with ecological processes of subordinate consequence. Ecological dynamics play a crucial role at the local level. They are governed by multilevel diversity among and within organisms of a species assemblage, such as differences in life history traits and heterogeneity of genetic and physiological properties, respectively.Key words: ecology, phylogeny, systematics, vesicular – arbuscular mycorrhizae.

ISSN:0008-4026    

DOI:10.1139/b95-221

出版商:NRC Research Press    

年代:1995

数据来源: NRC

摘要:

For microfungi, the understanding of the extent of their biotic diversity and of their ecological function remains underdeveloped. An insufficient number of specialists are available to collect and document the world's microfungi. Organizations that exploit microfungi as a source of chemical products or for biotechnological applications also may need to assess microfungal diversity to meet their specific objectives. During future inventories of biomes that are deemed of high biological interest or that may harbor species of commercial potential, methods for enumerating microfungi must be made more efficient, and fungal communities should be evaluated in such a way as to extract the maximum information. Rapid isolation techniques can be used to deliver high species diversity and obtain quantitative estimates of fungal species diversity and abundance. These methods, some previously developed by soil ecologists, rely heavily on selective media, dissection, physical and chemical elimination of contaminants, knowledge of spore behavior, and manipulation of incubation conditions. The rapid expansion of our knowledge of endophytes in woody plants exemplifies the success of this approach. Whenever rigorous isolation strategies have been applied to unstudied substrates, an unrealized depth of species diversity has been revealed. When methods are standardized, richness of different fungal communities, geographic variation within communities, or effectiveness of isolation procedures can be quickly and quantitatively compared. Exploration of complex substrata via indirect isolation expands the view of the fungal community in a way that complements traditional mycological collecting. However, fungi isolated into culture are often impossible to identify based on morphology. The utility of the rapid isolation approach to the inventory problem is illustrated with experiences with microfungi from rain-forest leaf litter.Key words:fungal metabolites, industrial microbiology, microbial diversity, natural products.

ISSN:0008-4026    

DOI:10.1139/b95-222

出版商:NRC Research Press    

年代:1995

数据来源: NRC

摘要:

Factors contributing to the species richness of fungal pathogens infecting grasses were explored through statistical analyses of data derived from a computerized data base on fungi on plants in the United States and from grass floras. The total number of fungal species infecting each grass species, as well as numbers of smuts, rusts, and systemic clavicipitaceous fungi, were compiled. Host characteristics included grass subfamily, the number of species in the genus, geographic range, life history, and their status as native versus alien species, and crop versus noncrop species. Analyses indicated that the best predictor of pathogen species richness per host is host geographical range. Grass subfamily, life history, and status as crops or native species also were significantly correlated with pathogen load but explained less variation than host geographical range. Pathogen species richness per host showed a strong trend to increase with increasing latitude. Extensive sampling of fungal pathogens from selected grass species is needed to provide an independent measure of accuracy of the data base.Key words: biodiversity, fungi, grasses, pathogens, species richness.

ISSN:0008-4026    

DOI:10.1139/b95-223

出版商:NRC Research Press    

年代:1995

数据来源: NRC

摘要:

Diversity has various meanings but generally they reflect the variation in species assemblages within a community. Species establish interpopulation relationships that lead to stable community structure, and stable and resilient communities by definition contain a certain level of diversity. Communities with too great or too little diversity predictably undergo rapid change. Studies of fungal diversity have been limited by taxonomic and logistical difficulties in collecting and defining fungal individuals and species. Succession of fungi on substrates, seasonal fluctuations, inconsistent isolation techniques, and other considerations have also led to problems in assessing fungal species diversity. Although the problem has now been identified it is not likely that significant additions to our taxonomic knowledge will soon be useful in saving rapidly disappearing ecosystems. However, calculations of fungal diversity are not limited to taxonomic information. Several approaches provide measurements of functional diversity in situations where taxonomic information is poorly defined. These include using binary biochemical and physiological descriptors to characterize isolates, evaluating enzymatic capabilities for utilizing particular substrates and extracting DNA or RNA from the soil or other substrate and probing for genes that code for functional enzymes. Such functional approaches can provide timely information on the contribution of fungi to community diversity and toward the establishment of predictors of community stability. This paper reviews the problems in assessing fungal diversity and evaluates potential techniques for determining fungal diversity from a functional perspective.Key words: fungal, microbial diversity, biodiversity, ecology.

ISSN:0008-4026    

DOI:10.1139/b95-224

出版商:NRC Research Press    

年代:1995

数据来源: NRC

摘要:

The two approaches, classical and inundative, which can be used to exploit fungi for weed biocontrol, are described and discussed. It is concluded that classical biological control involving the release of coevolved natural enemies, typically highly specific biotrophs into an exotic ecosystem, is the most environmentally and economically acceptable long-term strategy for controlling alien weeds, particularly in conservation areas. Mycoherbicides, based mainly on endemic nectrotrophs, have still not realized their full potential, mainly owing to problems with formulation, application, and market size, but with improved technology these may play an increasingly significant role in agricultural ecosystems. Virulent pathogens with broad host ranges offer the most commercial potential, if these can be tailored to suit individual crop systems. The initial selection of suitable biocontrol agents, based on field, herbarium, and literature surveys is outlined, whilst the problems involved in making the final selection are analysed in detail, especially those relating to taxonomy, biology, and host specificity. Examples are given of fungal pathogens that are being or could be employed for control of some major tropical weed species.Key words: fungi, classical biocontrol, mycoherbicides, tropics, conservation.

ISSN:0008-4026    

DOI:10.1139/b95-225

出版商:NRC Research Press    

年代:1995

数据来源: NRC

摘要:

The nematophagous fungus,Verticillium chlamydosporium, has considerable potential as a biological control agent for root-knot nematodes on a range of crops. The fungus is a general facultative parasite that attacks the eggs of several nematode species. The biology of the fungus is reviewed and the need for a detailed understanding of its ecology for its rational use as a biological control agent is highlighted. Isolates of the fungus must colonize the rhizosphere to be effective control agents. Plants differ in their ability to support the fungus and greatest control is achieved on those cultivars that support abundant growth of the fungus but produce only limited galling in response to nematode attack. On such plants, most eggs produced by nematodes are exposed to parasitism by this nematophagous fungus in the rhizosphere.Key words: biological control, nematophagous fungi, root-knot nematodes,Verticillium chlamydosporium.

ISSN:0008-4026    

DOI:10.1139/b95-226

出版商:NRC Research Press    

年代:1995

数据来源: NRC

摘要:

Fungi are among the most important microbial pathogens of grasshoppers with potential for development as biological control agents. Unlike most other insect pathogens that must be ingested to initiate disease, fungi generally invade insects via the external cuticle. The most common fungi that are pathogenic to grasshoppers areBeauveria bassiana,Metarhizium anisopliae,Metarhizium flavoviride,Sorosporellasp., and fungi in theEntomophaga gryllicomplex. A review of the latest information on the development of these fungi as microbial control agents of grasshoppers is presented. Species in theE. gryllicomplex are being used in classical biocontrol. This has resulted in controversy as there are indigenous nonpest grasshopper species that may be affected through introduction of the nonindigenous fungal strains.Beauveria bassianaandM. flavovirideare being developed for inundative control. These fungi can be mass produced and applied with equipment used for conventional pesticides. Conidia are applied either at ultralow volume in oil, as oil emulsions, or as bran-bait formulations. Field trials in Africa and North America have demonstrated significant grasshopper reductions. Improvements in formulation and inoculum targeting may further improve their efficacy.Key words: grasshoppers, locusts, microbial control,Beauveria bassiana,Entomophaga grylli,Metarhiziumspp.

ISSN:0008-4026    

DOI:10.1139/b95-227

出版商:NRC Research Press    

年代:1995

数据来源: NRC

摘要:

Understanding biological control of plant diseases is dependent on an understanding of succession in microbial communities. The colonization of aboveground plant parts by saprophytic microbes is not well understood, but it appears to follow the same model as that in soil communities. When a nutrient source is added, such as plant debris, there is a succession of organisms organized along a spectrum of complexity of carbohydrate utilization. A similar phenomenon may occur during the colonization of plant parts newly exposed by natural development or by wounds, upon which many pathogens depend to serve as sites of infection. These nutrient utilization strategies have been interpreted as indicative ofr(rapidly utilizing simple sugars) andK(slowly utilizing lignin) life strategies. If the concepts ofrandKspecies are applicable to microbes, it could indicate what type of interaction would be most likely to be successful for biological control. For example, pathogens that arerspecies may be better controlled by competition, andKpathogenic species better controlled by parasitism. However, for any interaction to take place, the control agent's environmental requirements, both biotic and abiotic, must overlap with that of the pathogen. The concepts of ecological succession andrandKspecies, if appropriate for microorganisms, may prove very valuable when developing biological control strategies.Key words: antibioses, competition, island biogeography, parasitism.

ISSN:0008-4026    

DOI:10.1139/b95-228

出版商:NRC Research Press    

年代:1995

数据来源: NRC