Phylogeny of Marine Ascomycota

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基本資料

Project title

Code/計畫編號

NSC98-2621-B019-002-MY3

Translated Name/計畫中文名

海洋子囊菌門之親緣關係史研究

Project Coordinator/計畫主持人

Ka-Lai Pang

Funding Organization/主管機關

National Science and Technology Council

Department/Unit

Institute of Marine Biology

Website

https://www.grb.gov.tw/search/planDetail?id=2222063

Year

2011

Start date/計畫起

01-08-2011

Expected Completion/計畫迄

31-07-2012

Bugetid/研究經費

1050千元

ResearchField/研究領域

生物科學

海洋真菌在傳統分類上可分為高等有絲真菌和低等游動孢子生物(包括破囊壺菌及海生疫病菌) 。在已發現的517 種高等有絲真菌中，有417 種屬於子囊菌門、12 種屬於擔子菌門和88 種的有絲分裂真菌。在海洋真菌的分類中，孢子和孢子附屬物形態及其個體發生為最重要的準則，但形態特徵已不足以把海洋真菌作一個合理的分類，原因包括: (1) 真菌形態特徵少；(2) 對形態演化的認識不足；及(3) 某些形態特徵是從趨同演化而來的。核醣體基因常用來做與真菌分子分類和演化有關的研究。核醣體的小亞基次單元體屬高度保留序列，可用作門、綱、目及科的分類；大亞基次單元體的變異較大，可用作科、屬及種的分類；間隔序列基因易變性更高，可用作屬以下的分類。到目前為止，海洋真菌的分類並不十分理想，因其形態特徵比其他真菌類更多元化，而很多有絲分裂的真菌也並未被歸類在現有的有性特徵分類系統中。因此，本研究計劃有三大目標: (1) 把在台灣發現的新種海洋真菌做進一步的歸類； (2) 確定爭議較大的屬，如： Aniptodera、Ceriosporopsis、Halosarpheia 及Lulworthia 與其相關屬的親緣關係； (3) 把海洋有絲分裂真菌(包括Cirrenalia 及Trichocladium) 歸類在現有的分類系統中。本研究將把從台灣分離出的菌種，做核醣體基因的分離和序列分析，以解釋以上所提出的問題。研究結果將對海洋真菌的分類和形態演化有重大的影響。Traditionally, marine fungi were commonly classified as ‘higher’ filamentous fungi (Ascomycota, Basidiomycota and mitosporic fungi) and ‘lower’ zoosporic fungi (thraustochytrids and halophytophthoras). Among the 517 higher marine fungi recently described, 417 species belong to Ascomycota, 12 species to Basidiomycota and 88 species to anamorphic fungi. The Halosphaeriales is the largest order of marine fungi with 121 species in 52 genera, of which 32 are monotypic. Morphology has long been important in the classification of marine fungi. In Halosphaeriales, morphology and ontogeny of ascospore and ascospore appendages are instrumental in the delineation of different genera in the order. Often there are insufficient morphological characters that can be used to make taxonomic decisions and also, the evolution of most morphological characters is difficult to trace. Some structures are possibly acquired by parallel or convergent evolution such as appendaged ascospores, deliquescing asci and bitunicate asci. As a result, morphology alone is no longer sufficient for the classification of marine fungi. Nuclear ribosomal RNA gene clusters have been used to answer different levels of taxonomic questions and test various evolutionary hypotheses. The nuclear small subunit (18S or SSU) ribosomal RNA gene is highly conserved and is suitable for inferring phylogeny at the phylum, class, order and family levels. The nuclear large subunit (28S or LSU) ribosomal DNA region is a more variable part of the whole ribosomal genes that is particularly suitable for phylogenetic study at lower taxonomic levels including family, genus and species. The use of intergenic spacer regions (ITS) for phylogenetic construction is restricted to very closely related taxa (at or below genus level), because of their extremely variable property, both in length and base composition. The current research programme is proposed with the following research questions in mind: (1) higher taxonomic position of a number of marine fungi is currently unknown; (2) generic circumscription of a number of marine fungi is unsatisfactory; and (3) many marine anamorphic (asexual) fungi have not been linked to their teleomorphs (sexual stage). Therefore, the main objectives of the proposed study are: (1) to determine the higher taxonomic classification of a number of new filamentous fungi isolated from Taiwan; (2) to resolve the phylogenetic relationships of the following problematic genera complexes in the Halosphaeriales and the Lulworthiales: (I) Aniptodera/Halosarpheia complex, (II) Ceriosporopsis complex and (III) Lulworthia complex; and (3) to link a number of anamorphic marine fungi to their teleomorphic counterparts including: (I) Cirrenalia and (II) Trichocladium. Marine fungi will be collected extensively in the first year in coastal environments around Taiwan with particular reference to the fungi in the Halosphaeriales and the Lulworthiales. Phylogenetic analysis of the ribosomal RNA gene clusters of the marine fungi collected in Taiwan and those deposited in the culture collection at National Taiwan Ocean University will be used to answer the taxonomical and evolutionary questions raised above. Results of the proposed study will provide a more natural classification of marine fungi, and allow the evolution of marine fungi be traced back, thus, implicating evolutionary important morphological characters for taxonomic studies.

DSpace CRIS

Phylogeny of Marine Ascomycota

基本資料

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