Selasa, Juni 21, 2011
Unknown
Taxonomy: Cordyceps, Cordycipitaceae, Hypocreales, Hypocreomycetidae, Sordariomycetes, Pezizomycotina, Ascomycota, Dikarya, Fungi.
Cordyceps and related fungi include over 500 species that are pathogens of arthropods and other fungi. Many species of Cordyceps are pathogens of insects pests and are promising candidates for biological control, which is an active area of research that may lessen our dependence on – and environmental impact of – synthetic pesticides. In addition, many species of Cordyceps and related fungi produce numerous biologically active compounds that function in pathogenicity. Some of these compounds have been exploited for use in medicine (e.g., Cyclosporin A from Tolypocladium inflatum), but countless others await discovery. An accurate understanding of the taxonomy and evolutionary relationships of these fungi will provide a predictive framework in which more focused and directed research in other fields of biology (e.g., biological control, drug discovery, etc.) can proceed.
The overarching goal of this research is to provide a more accurate basis for recognizing and delineating species through the production of a modern monograph. As such, this research involves extensive field collecting of specimens, which will improve our knowledge of species distributions and biogeographic patterns. Cordyceps is particularly abundant in East Asia and eastern North America, thus this project includes collaborations among scientists in China, Japan, Korea, United States and Thailand. Current taxonomic and phylogenetic hypotheses, which are mostly based on traditional interpretations of morphology and ecology, are being tested and refined through phylogenetic analyses of molecular and morphological data.
This research is part of the National Science Foundation "Partnerships to Enhance Expertise in Taxonomy" (PEET) program, which is dedicated to training the next generation of taxonomists. As a PEET project we are training students and postdoctoral research associates in taxonomy of fungi, an understudied group of organisms for which additional expertise and researchers are needed. This research is supported by the National Science Foundation under Grant DEB-0529752. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation.
Cordyceps is a broad term describing a group of ascomycetous fungi that have carved out a niche as endoparasites primarily of arthropods and also as symbionts of the ascomycete truffle genus Elaphomyces. Their life cycle can be divided between an asexual, haploid stage (the anamorph) and a sexual, dikaryotic stage (the teleomorph). The anamorph is capable of surviving upon numerous substrates, switching to the teleomorph phase only upon infection of an appropriate host. It is the teleomorph that produces the characteristic stroma, the fungus’ fruiting body, in which the sexually-derived ascospores are produced within the flask-shaped perithecia. The ascospores may produce a teleomorph immediately if they happen to infect an appropriate host, but more often they will again germinate into anamorphs on some other substrate. If that other substrate should be an arthropod outside of the clade capable of supporting teleomorph production, the anamorph can frequently still exploit it.
Cordyceps and related fungi include over 500 species that are pathogens of arthropods and other fungi. Many species of Cordyceps are pathogens of insects pests and are promising candidates for biological control, which is an active area of research that may lessen our dependence on – and environmental impact of – synthetic pesticides. In addition, many species of Cordyceps and related fungi produce numerous biologically active compounds that function in pathogenicity. Some of these compounds have been exploited for use in medicine (e.g., Cyclosporin A from Tolypocladium inflatum), but countless others await discovery. An accurate understanding of the taxonomy and evolutionary relationships of these fungi will provide a predictive framework in which more focused and directed research in other fields of biology (e.g., biological control, drug discovery, etc.) can proceed.
The overarching goal of this research is to provide a more accurate basis for recognizing and delineating species through the production of a modern monograph. As such, this research involves extensive field collecting of specimens, which will improve our knowledge of species distributions and biogeographic patterns. Cordyceps is particularly abundant in East Asia and eastern North America, thus this project includes collaborations among scientists in China, Japan, Korea, United States and Thailand. Current taxonomic and phylogenetic hypotheses, which are mostly based on traditional interpretations of morphology and ecology, are being tested and refined through phylogenetic analyses of molecular and morphological data.
This research is part of the National Science Foundation "Partnerships to Enhance Expertise in Taxonomy" (PEET) program, which is dedicated to training the next generation of taxonomists. As a PEET project we are training students and postdoctoral research associates in taxonomy of fungi, an understudied group of organisms for which additional expertise and researchers are needed. This research is supported by the National Science Foundation under Grant DEB-0529752. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation.
Cordyceps is a broad term describing a group of ascomycetous fungi that have carved out a niche as endoparasites primarily of arthropods and also as symbionts of the ascomycete truffle genus Elaphomyces. Their life cycle can be divided between an asexual, haploid stage (the anamorph) and a sexual, dikaryotic stage (the teleomorph). The anamorph is capable of surviving upon numerous substrates, switching to the teleomorph phase only upon infection of an appropriate host. It is the teleomorph that produces the characteristic stroma, the fungus’ fruiting body, in which the sexually-derived ascospores are produced within the flask-shaped perithecia. The ascospores may produce a teleomorph immediately if they happen to infect an appropriate host, but more often they will again germinate into anamorphs on some other substrate. If that other substrate should be an arthropod outside of the clade capable of supporting teleomorph production, the anamorph can frequently still exploit it.
Nonetheless, there do appear to be instances during the course of evolutionary history in which a Cordyceps has jumped between phylogenetically distant hosts. The genus Elaphocordyceps, for example, includes species that produce stromata on either cicada nymphs (Hemiptera) and Elaphomyces (Nikoh and Fukatsu 2000). Yeast-like descendants of a pathogenic Cordyceps found in termites (Isoptera) have become mutualist endosymbionts of plant hoppers (Hemiptera) (Suh, Noda and Blackwell 2001). This wholesale leaping between distant branches of the tree of life is not seen in other multicellular symbionts.
In this review, we will explore some of the developments from the past several years of research on Cordyceps sensu lato that might allow us to understand what makes them capable of performing symbiosis-switching feats not seen elsewhere in nature. In particular, we will attempt to develop some idea of the role that the generalist anamorph stage may play in host jumping and investigate factors that might play a role in the switch from anamorph to teleomorph once an appropriate host has been located.
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