Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/35879
標題: 胡瓜嵌紋病毒2b蛋白促進竹嵌紋病毒在寄主中系統性的移動及感染非寄主性植物
The 2b protein of Cucumber Mosaic Virus Facilitates Bamboo Mosaic Virus Systemic Spread in Host Plants and Infection in Non-host Plants
作者: 林信摯
Lin, Shinn-zhi
關鍵字: Bamboo Mosaic Virus (BaMV)
竹嵌紋病毒
Cucumber Mosaic Virus (CMV)
2b protein
胡瓜嵌紋病毒
2b蛋白
出版社: 農業生物科技學研究所
摘要: 胡瓜嵌紋病毒 (Cucumber mosaic cucumovirus, CMV) 寄主範圍相當的廣泛,可感染1,000種以上的植物,其基因體為三條正股的RNAs。經由RNAs序列比對,CMV系統(strains)可區分為三個次族群,分別為IA、 IB 和II。CMV RNA2可以轉錄出一條次基因體RNA 4a,並可轉譯出2b蛋白。2b蛋白能促進CMV在植物中長距離的移動及病徵的表現,並且也干擾植物的抗病機制,包括後轉錄基因靜默(post-transcriptional gene silencing, PTGS) 以及水楊酸誘發的病毒防禦(salicylic acid-mediated virus resistance)。CMV的寄主範圍如此廣泛,2b蛋白可能扮演一個重要的角色。本實驗首次成功的利用細菌大量的表現CMV次族群IA (NT9-CMV) 的2b蛋白並且製備血清,所製備的血清不只可專一的與細菌大量表現出來的2b蛋白作用,並且也可在NT9-CMV感染的植物中偵測到2b蛋白的表現。竹嵌紋病毒 (Bamboo mosaic potexvirus, BaMV) 是potexvirus group 的成員之一,其寄主範圍狹窄,主要感染竹類 (Bambusoideae)以及少數單子葉植物和Nicotiana benthamiana。為了要擴展BaMV的寄主範圍,本實驗將CMV-2b基因選殖於BaMV病毒載體中,構築出BaMV-2b。將此BaMV-2b重組株和BaMV野生株分別接種白藜(Chenopodium quinoa),並收集含有病徵的葉片,各別純化出BaMV-2b 和BaMV病毒,以此病毒作為後續實驗的接種原。兩種接種原等量分別接種在BaMV的寄主植物及多種非寄主植物上,結果發現在寄主植物N. benthamiana上,含有可表現2b蛋白的BaMV-2b病毒移動速度較野生株BaMV病毒快;而在非寄主植物上可發現BaMV-2b病毒可以感染許多野生株BaMV所無法感染的植物,其中包括了: N. rustica, N. tabaccum, N. samsun, Solanum tuberosum L.和Cucumis sativus L.。由實驗證據顯示來自CMV-NT9 的2b蛋白可以促進BaMV在寄主植物中系統性的移動,並且使得BaMV能夠感染其他非寄主性的植物。
Abstract Cucumber mosaic virus (CMV), infecting a very wide range of plant species (>1,000 species) is a positive-sense RNA plant virus with a tripartite genome. Based on RNA sequence homology, CMV has been divided into subgroup IA, IB and II. The CMV-2b protein which is encoded by a 3'-proximal ORF of the RNA 2 first identified in subgroup II CMV-Q and translated from a subgenomic RNA 4a. CMV-2b protein has the function in facilitating long-distance virus movement and symptom expression and has been identified as a viral counterdefence factor that interferes with the establishment of post- transcriptional gene silencing (PTGS) and salicylic acid-mediated virus resistance in plants. The 2b protein may play an important role in a wide host range of CMV. Previous, attempts by other laboratories to express the 2b protein of subgroup IA or IB in E. coli was unsuccessfully. In this work, we have successfully overexpressed the 2b protein of a subgroup IB CMV, NT9 strain, in E.coli and generated a polyclonal antibody against the 2b protein. The 2b antiserum can interact specifically with 2b protein that not only expressed in E.coli but also accumulated in NT9-CMV-infected plants. Bamboo mosaic virus (BaMV), a member of the potexvirus group with a narrow host range, infects primarily members of the Bambusoideae, few other monocotyledonous plants and Nicotiana benthamiana. In order to extend BaMV host range, we constructed BaMV derivative BaMV-2b by cloning the 2b gene of CMV NT9 strain into the BaMV vector. Using chimeric virus BaMV-2b and wild type BaMV as inocula, virus accumulation and systemic spread in the inoculated plants were compared. Our results suggest that the chimeric virus BaMV-2b engineered to express the 2b protein of CMV facilitated BaMV long distance movement in N. benthamiana (host plant) and enhanced infectivity of BaMV in N. rustica, N. tabaccum, N. samsun, Solanum tuberosum L. and Cucumis sativus L. (non-host plants).
URI: http://hdl.handle.net/11455/35879
Appears in Collections:生物科技學研究所

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