| 摘要: | 研究期間：10108~10207;Plant pathogenic cercosporoid fungi from tropical/subtropical areas General status of taxonomy Predominantly plant pathogenic hyphomycetes with relationship to the ascomycetous Mycosphaerellaceae and closely related families comprising ca. 3000 species worldwide are referred to as “cercosporoid fungi”. Presently, some generic concepts are mainly based on morphological characteristics, other ones mainly on molecular data. Most species are plant pathogens showing high host specificity, including pests of economically important cultivated plants. Frequently a single plant species serve as host for several genera and species of cercosporoid fungi. Due to these diverse hosts, many fungi on them are rarely collected and studied. Cultures and DNA data are not available for many species. In certain species, even those where DNA data are present, important morphological data, such as ultrastructure and structure of interaction with the host plant, are lacking. Taxonomy of cercosporoid fungi in tropical/subtropical areas Numerous tropical/subtropical taxa were described in Asia and Latin America in the first half of the 20th century. Many descriptions did not include illustrations and have not been updated due to modern standards of systematics. Species excluded from cercosporoid fungi have often not been accommodated in other groups and thus became taxonomically “orphaned”. On the other hand, several hypothetically true cercosporoid species described in non-cercosporoid genera remained “cryptic”. The present focus of research of cercosporoid fungi in tropical America is Brazil, based on morphology and infections experiments. We established a new focus for study of neotropical cercosporoid fungi in Central America (Panama). In tropical Asia, most species were described in India by morphology. Though located at the northern border of the tropical belt, our new records of fungi previously known only for India and Southeast Asia illustrate that Taiwan is an excellent place for studying tropical cercosporoid fungi. By a morphological approach, a well-prepared alpha-taxonomic base was provided in a monograph on cercosporoid fungi of Taiwan (Hsieh & Goh 1990). In spite of this huge work, many taxa were not yet covered, and several additional new genera, species, and new records for Taiwan were published, in most cases amended by ultrastructural and molecular analyses by us. Aims Since many weeds introduced into Taiwan originate from tropical America and most tropical cultivated plants are pantropically distributed, these plants are hypothesized to share a similar distribution of cercosporoid fungi in Panama and Taiwan. As indicated by our recent publications, several new taxa and records are to be expected from both countries. In addition, by cultivating, DNA analysis and detailed light and scanning electron microscopy, new resources are provided that will allow an easier and quicker identification of the species by other researchers. In our analyses, hypothetical geographical and host correlations with phylogenetic clades of cercosporoid fungi from both countries will be tested. Taxonomical re-examination of certain species originally not described in cercosporoid taxa and species excluded from cercosporoid fungi will allow accommodation of wrongly placed species in more adequate genera by new combinations. Living cultures will be made available for conservation and further research. |
