瓶爾小草科蕨類菌根之研究

Abstract

囊叢枝菌根菌，是一群與植物根部形成共生體的真菌，在分類上屬於繡球菌門。這類真菌可與大多數植物形成菌根，分佈棲地也極為廣泛；本群真菌會因宿主植物的不同而在根部組織中出現不同的感染形態。雖有許多學者研究菌根，但是關於菌根的感染形態研究並不多，而蕨類菌根的討論亦是很少，惟研究文獻中發現其菌根有些較為特殊之感染方式。本研究以瓶爾小草科為研究對象，探討該科內各代表屬種的菌根形態，並分析該形態在科內的一致性以及形態上的定位。 本實驗共研究臺灣產瓶爾小草科中的六個種類，利用根部染色，以光學顯微鏡、掃瞄式電子顯微鏡、穿透式電子顯微鏡做形態觀察，並檢測土壤中的pH值，以及根圈孢子的分離與鑑定。 經研究發現瓶爾小草科之孢子體的菌根形態大致相同，惟此形態與一般所定義之菌根不同，是屬於中間型的表現；再加上叢枝體的形態獨特，文獻中僅有於其他瓶爾小草科蕨類中出現，在其他植物中並未報導過。因此，綜合以上兩點觀察與既有文獻的報導等事實，筆者認為本科蕨類同屬一個菌根形態，而此形態尚未有人提出成為一個獨立形態，筆者建議將其命名為Ophioglossum-type。而根圈土壤的pH值接近中性，惟狹葉瓶爾小草的土壤偏鹼性，帶狀瓶爾小草偏酸性；土壤內孢子數量部分，每20g土壤約有1-50顆孢子，惟帶狀瓶爾小草土壤中的孢子數極多，有3000多顆，種類上也與其他實驗材料不相同，帶狀瓶爾小草的附生環境對於菌根菌或許為一獨特的生存環境，而菌根孢子的傳播途徑，除風力外尚有其他動物因素必須考慮探討。

Abstract Vesicluar-Arbuscular mycorrhizal fungi , is a group of fungi can symbiosis with plant , belong Glomeromycota , kigdom Fungus . these fungi can form mycorrhiza with most plants and distributed world-wide. But according to the differences of host plant , the mycorrhizal morphology are reveal Six species of Ophioglossaceae (Ophioglossum petiolatum、O. pendulum 、O. austroasiasticum、 O. thermale 、Botrychium formosanum、 Helminthostachys zeylanica) have been study for mycorrhizal status. All of these plants present a different arbuscular morphology : the collapsed arbucle shows the sac-like structure . And in the species, O. petrolatum , we saw how the collapsed arbuscle developed : the arbuscle is trunk-like in the begins, as the normal arbuscle . Sooner, the terminal branches start swelling. Finally, the arbuscle become a cluster of small vesicles. O. pendulum also has the swelling arbuscle , too. Both inter- or intra-cellular hyphae are present in root tissue. According to these observation, we conclude the mycorrhizal morphology of Ophioglossaceae is consistent , and could be a new morphological type exist. Oil drops and crystal-like material also seen in the stage of collapsed arbuscle . Oil drop should be the carbon source transfer from plant and mycorrhizal fungi change carbon source into oil drops. The crystal-like material could be the polyphosphate which mycorrhizal fungi transfer phosphate in that form. the soil ph and rhizosphere mycorrhizal fungi spore also determined. The lower pH and high soil mycorrhizal fungi spores in O. pendulum shown that epiphyte maybe needs low ph to degenerate litter into the resource they can use ,and mycorrhizal fungi may play a impotent role in this kind of habitat.