A Five-Gene Region Phylogeny for Cordyceps and the Clavicipitaceae (Ascomycota)

Oregon State University, Corvallis OR

Investigators

Abstract

0129212 Spatafora Cordyceps is a genus of ascomycete fungi that includes over 300 described species, most of which are pathogens of insects and other fungi. It is a member of the family Clavicipitaceae, which also includes numerous species of plant pathogens. The Clavicipitaceae are fascinating in that all species must associate with other organisms in nature in order to complete their life cycle. This association is usually antagonistic, resulting in disease and death of the host organism. Many of these fungal pathogens are only known from asexually reproducing states, which often inhibits accurate identification and inferences about their evolutionary origins. Results from prior NSF supported research by Dr. Spatafora are consistent with an interpretation of host jumping through evolutionary time and multiple losses of sexual reproduction. The data reject previous hypotheses pertaining to the evolution of this group of fungi, which is reflected in an outdated classification that does not reflect true relationships or possess predictive value. Research funded by this grant will build upon previous data by collecting and analyzing DNA sequences from five nuclear and mitochondrial genes. The overall goal of this research is to develop robust and testable hypotheses for the evolutionary relationships of Cordyceps and related fungi, which in turn will provide a basic understanding of the evolution of host association, pathogenicity, and mode of reproduction. To develop such hypotheses, the diversity of Cordyceps species will be sampled with a special emphasis on East Asia, the most species rich region of the world for the genus. In order to sample this diversity, Dr. Spatafora will collaborate with researchers from Japan, Korea, and Thailand. They will assist in collecting of species and he will provide training opportunities in molecular evolution of fungi for a limited number of graduate students from each of these countries. The students will visit the laboratory at Oregon State University for a period of approximately six months, after which they will return to their home institutions with the goal of transferring this technology. Many species of Cordyceps and related fungi of the Clavicipitaceae are important in both agriculture and medicine. Numerous species of Cordyceps are pathogens of insects and are promising candidates for biological control of insect pests. Biological control is an active area of research that may lessen the dependence on, and environmental impact of, pesticides. Central to development of efficient biological control systems is an accurate understanding of both the relationships of candidate species and the overall pattern of host association and niche specialization. In addition, many species of Cordyceps and the Clavicipitaceae produce biologically active compounds that function in pathogenicity. Some of these compounds have been exploited for use in medicine (e.g., Cyclosporin A from Cordyceps subsessilis), but others likely await discovery. An understanding of the 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.