2007-08-012024-05-18https://scholars.lib.ntu.edu.tw/handle/123456789/706771摘要：利用生物防治菌來防治植物病害一直是長久以來農業上的重要課題之ㄧ，已有一些成功的案例指出生物防治的可行性。隸屬於擔子菌亞門、無褶菌目 (Aphyllophorales)、皮殼菌科 (Corticiaceae)的Hyphoderma mutatum 具有毒殺線蟲的能力，初步分析顯示毒殺物質存在於菌絲內，當線蟲取食其細胞質十二個小時內便會死亡，於是該菌的菌絲便有機會能侵入線蟲而利用線蟲作為其營養來源 (Tzean and Liou, 1993)。由於此線蟲毒殺力非常強，且已知該菌能毒殺之線蟲範圍包括松樹線蟲、水稻白尖病原線蟲及草莓葉芽線蟲等經濟上重要之病原，若我們能對該菌有更多的研究，進而分離出該毒性物質的話，應當對於線蟲防治上有相當程度之影響。之前的研究發現置於菌絲粗萃取物中的線蟲並不會被毒殺，這造成萃取出不同化學物質後分析其線蟲毒性之困難度，因為毒性物質可能必須在被線蟲食入後才會有作用。於是我們一方面繼續尋找分析方法的同時，希望也能針對該菌之毒殺線蟲力進行特性分析，或許可以發展出一套利用該菌有效的防治方法。初步想法希望能找到該菌中與線蟲毒殺力有關之基因，導入植物中讓植物自行產生該毒素來控制線蟲病害，或者是從該研究中找到更多資訊可供作設計施藥時使用。為了這個長遠的目標，我們打算從遺傳學的角度著手，首先建構薄殼菌Hyphoderma mutatum之突變菌株庫 (mutant library)，然後利用此突變菌株庫篩選出失去毒殺線蟲能力的突變菌株。之後便可由這些突變菌株中，鑑定出與毒殺線蟲力有關聯性之基因。未來便可藉由基因的特性分析，一步步了解在Hyphoderma mutatum 中毒殺線蟲物質的構造及製造該物質之調控機制，最終希望能分離及純化該毒殺線蟲物質，或藉由這個基因調控機制所提供之資訊，發展出有效防治松材及葉芽線蟲之方法。<br> Abstract: Biocontrol is one of the important topics in plant pathology. Until now, several biocontrol agents have been successfully applied in the field, eg. Bt toxin. In 1992, Liou and Tzean found that Hyphoderma mutatum, which belongs to subdivision Basidiomycotina, family Aphyllophorales, order Corticiaceae, had ability to kill nematodes (Liou and Tzean, 1992). It has been demonstrated that nematodes die within 12 hours after feeding on the hyphae of Hyphoderma mutatum, indicating that it contains unknown toxic components in the cytoplasm. After the nematodes are dead, the hyphae can penetrate the cuticle and grow inside the nematodes (Tzean and Liou, 1993). Hyphoderma mutatum has very strong nematicidal activity against several economically important nematodes, including pine wood nematode (Bursaphelenchus xylophilus) and bud nematode (Aphelenchoides sp.). If we further characterize this fungus, we might have great discover on control of the diseases caused by these phytopathogenic nematodes. We have previously started to study this fungus. However, that no nematicidal effect can be observed when Aphelenchoides sp. was co-incubated with crude extract of fungal hyphae impeded our further analysis of nematicidal activity of Hyphoderma mutatum. We will continue to explore effective bioassay methods for fractions isolated from the fungal mycelia. But in the meantime, we will try different approaches for the same goal of identification of the nematicidal compounds. To accomplish this purpose, mutant libraries of Hyphoderma mutatum will be generated and used to identify gene(s) involved in nematicidal activity of Hyphoderma mutatum, especially toxin-producing genes. Random mutagenesis of Hyphoderma mutatum will be conducted using either Agrobacterium-mediated transformation or transposon tagging to generate a mutant library, which can be used to screen for mutants losing their ability to kill nematodes. In the future, we can clone and characterize the genes responsible for this nematicidal activity. Although it may take more time, we will obtain more information for the development of biocontrol strategies against these harmful nematodes.薄殼菌屬線蟲毒殺力Hyphoderma mutatumnematicidal activity