| 摘要: | 全世界植物病害主要的子囊菌類Mycosphaerellaceae 科真菌及親源相近的科約有 3000 種，被認為是cercosporoid 型真菌，現今一般分類概念主要是依據形態特徵，其次是分子層級的數據。大多數的種是具有植物病原性且是具有專一性，包括重要經濟作物的有害病菌。一種植物常常是被好幾個屬或種的cercosporoid 型真菌感染，由於寄主的多樣化，以致於許多這類真菌鮮少被採集及研究。對許多這類真菌而言，菌種及DNA 資料並無法提供足夠的鑑定依據，某些特定的種甚至於已有DNA 資料及重要的形態特徵，但像是與寄主植物間交互關係的超微細顯微構造，卻仍闕如。無數的熱帶及亞熱帶的種是在二十世紀前五十間在亞洲及拉丁美洲所描述的，很多菌種描述並沒有形態構造圖及更新為現代系統分類標準，排除cercosporoid 型真菌，很多種常常沒有與其他的類群相容而演變為分類上的”孤兒”。另一方面，許多應該是 cercosporoid 型的種卻被描述鑑定為非cercosporoid 型的屬，被隱藏而鮮為人知。目前專注在cercosporoid 型真菌研究的是熱帶地區的巴西，以形態及感染試驗為主，我們曾在亞熱帶地區的巴拿馬進行cercosporoid 型真菌研究。在熱帶地區的亞洲，大多數的種是在印度以形態特徵發表，由於位於熱帶地區的北端，我們先前研究的新記錄種僅在印度及東南亞發現，因此台灣是一個極適合研究cercosporoid 型真菌的地區。藉由形態特徵，1990 年謝文瑞教授等人已建立cercosporoid 型真菌圖鑑，除了這項艱鉅的工作外，尚有很多種當時並未被調查及發現，而我們已經發表台灣很多新屬、新種及新記錄種，且多數都有超微細顯微構造及分子生物學親源性分析。由於很多草本植物種是從熱帶地區的美洲引進台灣，多數的栽培種是泛熱帶分佈，因此這些植物被認為台灣與巴拿馬有相似的cercosporoid 型真菌分佈，我們近年來的發表也指出，很多新屬種和記錄種在這兩個地區是可預期被發現的。除此之外，藉由菌種分離培養、DNA 定序分析及詳細的光學和掃描式電子顯微鏡形態特徵描述，可以比較容易且快速的鑑定種。本計畫將針對這兩個國家cercosporoid 型真菌親源樹狀圖與地理位置和寄主間關連性進行分析，某些以前不是被描述為cercosporoid 型真菌的種也將再進行分類鑑定複核，被描述為cercosporoid 型真菌而鑑定錯誤而被放置在錯的屬也將重新組合，活菌種則妥善保存，提供日後研究。 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. 研究期間：10001 ~ 10007 |
