SSU rRNA序列分析與型態鑑定證實Geosiphon pyriforme為繡球菌目的演化祖先成員

Geosiphon pyriforme Is Evidenced to be an Ancestral Member of the Glomales by Morphological Identification and SSU rRNA Analysis

於德國和奧地利天然生育地所發現的多核細胞土壤真菌Geosiphon pyriforme（Kütz.）v. Wettstein，能與念珠藻屬（Nostoc）形成共生，屬於典型的內生細胞體（endocytobiosis）。該菌喜好生長於潮濕且無機養分含量貧瘠的土壤表層，尤其是缺磷的環境，其細胞壁含有幾丁質，經過幾番爭論，最後自立一個科（Geosiphonaceae）。本篇報告討論其孢子型態及超顯微構造均與內生菌根菌的繡球孢子屬（Glomus）極相似；且其共生系統中與內生菌根菌具有同型的養分流動模式；另以SSU rDNA 序列進行分子系統發生學分析，所有結果皆顯示Geosiphon pyriforme 與內生菌根菌繡球菌目（Glomales）具有親緣關係，因此推測該菌是繡球菌目演化的祖先群成員。 Geosiphon pyriforme ( Kütz.) v. Wettstein is a coenocytic soil fungus was found in the natural habitats in Germany and Austria. It is presently known to be a typical example of a fungus living in endocytobiotic association with Nosto (cyanobacterium). They prefer living on the surface and in the upper layer of humid, nutrient poor soils. Especially, in phosphorus-defect site. The cell wall of Geosiphon contains chitin. After several disputation, the organism was described as typifying its own family, Geosiphonaceae. In addition, shape and wall ultrastructure of the Geosiphon spores and their cytoplasm resemble those of Glomus spores. Also, the nutrient flows interfaces of the Geosiphon and AM symbiosis are homologous. Then, the small-subunit (SSU) ribosomal RNA genes were analyzed and aligned with other sequences. The result shows Geosiphon pyriforme has evolutional relation with Glomales and is also one of its ancestral members.

Geosiphon pyriforme ( Kütz.) v. Wettstein is a coenocytic soil fungus was found in the natural habitats in Germany and Austria. It is presently known to be a typical example of a fungus living in endocytobiotic association with Nosto (cyanobacterium). They prefer living on the surface and in the upper layer of humid, nutrient poor soils. Especially, in phosphorus-defect site. The cell wall of Geosiphon contains chitin. After several disputation, the organism was described as typifying its own family, Geosiphonaceae. In addition, shape and wall ultrastructure of the Geosiphon spores and their cytoplasm resemble those of Glomus spores. Also, the nutrient flows interfaces of the Geosiphon and AM symbiosis are homologous. Then, the small-subunit (SSU) ribosomal RNA genes were analyzed and aligned with other sequences. The result shows Geosiphon pyriforme has evolutional relation with Glomales and is also one of its ancestral members.