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The variation within Aphelenchoides besseyi in Taiwan
分別由烏日、大湖、嘉義分離之水稻葉芽線蟲(Ar)、草莓葉芽線蟲(As)、山蘇花葉芽線蟲(Af)及中興大學植病系線蟲室培養之水稻葉芽線蟲(Ab)，形態測量值皆與Aphelenchoides besseyi的標準範圍吻合。以掃描式電子顯微鏡觀察細微構造，四者無明顯差異。於長滿Alternaria citri菌絲之馬鈴薯葡萄糖瓊脂(PDA)斜面試管上培養，線蟲生長溫度範圍為16-32℃，最適生長溫度為Ar 25 ℃、Ab 28-30 ℃、As 32 ℃與Af 30 ℃。於28 ℃時，Ar於Alternaria citri上完成一世代須5-6天，Af與Ab須5天，As須4-5天。對山蘇花、草莓、水稻及秋石斛病原性測試的結果顯示，四者皆可感染草莓與水稻，僅Af對山蘇花具病原性，As則無法感染秋石斛。交叉交配試驗的結果發現，各處理皆有子代產生，且子代仍然具有繁殖產生後代的能力。子代與親代之形態無差異，且各子代對草莓均有病原性，僅有Afs、Afb及Afr (以Af為雄性父本雜交產生之子代)對山蘇花有病原性。除Afr及Arf之外，其他子代中皆無雄蟲存在。本研究發現，將Ab和As培養在Alternaria citri後，兩者均產生孤雌生殖現象，與Huang等人於1979年報告之A. besseyi只行兩性生殖迥異。由隨機增幅核酸多型性分析(random amplified polymorphic DNA, RAPD)的結果可看出，利用隨機引子S1、S4、S7、S8與S10增幅出之片段，Af與As、Ar、Ab差異大，As和Ab差異小。以共同引子對18S/26S增幅葉芽線蟲之核糖體核酸內轉錄區間(internal transcribed spacer, ITS)，可得一大小約1,000 bps的增幅產物，經酵素Rsa I剪切後，Af可得一大小約1,000 bps的片段，As與Ab為約700 bps的片段，Ar為約800 bps的片段。由結果得知，山蘇花葉芽線蟲、草莓葉芽線蟲與水稻葉芽線蟲於形態上無差異，但在生理生態上已有明顯不同，因此，台灣葉芽線蟲A. besseyi種內於生理特性上確實存在變異情形，但此變異與寄主和來源地區無明顯相關性。
The designations and sources of nematode species were: two populations of Aphelenchoides besseyi from rice plants from the Wjjh (Taichung county) (Ar) and plant nematology laboratory at Department of Plant Pathology NCHU (Ab); one population from strawberry from Dahu (Miao Li) (“As”) and one population from fern from Chia-yi (Chiayi county) (Af). There was no differences among morphology of four populations. The range of growth temperature of the four nematodes that cultivated on PDA slant with Alternaria citri was from 16 to 32 ℃, and the optimum temperature for Ar development was 25 ℃, Ab was 28-30 ℃, “As” was 32 ℃and Af was 30 ℃. Ar needed 5-6 days to finished a life cycle which cultivated on PDA slant with Alternaria citri at 28 ℃, Ab and Af needed 5 days, and As needed 4-5 days. All of them infested strawberry, but only Af attacked fern. “As” could not infect bailey. The result of mating test showed that we could observe off springs in every treatment, and they were able to reproduce . The morphology of parental generations and off springs had no significant differences . All the off springs could infect strawberry while only Afs, Afb, and Afr could infect fern. Besides Afr and Arf, there males of Afs, Afb and Ars could not be find. The phenomenon of parthenogenetic was observed on As and Ab that cultivated on PDA slant with Alternaria citri. The results of random amplified polymorphic DNA (RAPD) showed that the amplification fragments of Ar, Ab, As and Af were different, but the fragments of As and Ab were alike. We used 18S and 26S primers (Ibrahim et al., 1994) to amplify ribosomal DNA (rDNA) of nematodes, and all populations yield a product at the size of pproximately 1,000bp. When amplified rDNA fragments were cut with restriction enzyme Rsa I, Af resulted a band of that was uncut; As and Ab changed into 700bp and Ar changed into 800bp, both with a minor band that had a size indistinguishable from Alternaria citri products.
|Appears in Collections:||植物病理學系|
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