Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/31496
標題: 台灣地區劍線蟲種類之鑑定與變異
Identification and variation of Xiphinema species from Taiwan
作者: 陳殿義
Chen, Diann-Yih
關鍵字: 劍線蟲
identification
鑑定
變異
核糖體DNA
內轉錄區間序列
ribosomal DNA
Xiphinema americanum group
X. brevicollum
X. incognitum
X. diffusum
X. oxycaudatum
X. elongatum
出版社: 植物病理學系
摘要: 自1996年起,主要於台灣的中南部及花東等地區,以改良式柏門氏漏斗分離法,於37個採集點中共計分離到56群劍線蟲,主要經由雌蟲的形態測量值比對後,其中包括屬於Xiphinema americanum group的X. brevicollum、X. incognitum、X. diffusum、X.oxycaudatum及X. silvaticum、以及非屬該群集內的X. elongatum、X. insigne及X. hunaniense等共8種新記錄劍線蟲種類。經由各群中前後齡期幼蟲和雌蟲的替代齒針和功能性齒針長度的比對,前述8種劍線蟲中只有X. oxycaudatum的生活史中具有3個幼蟲齡期,其餘7種劍線蟲皆為4個齡期。同樣由各群中前後齡期幼蟲和雌蟲的替代齒針和功能性齒針的長度平均值皆呈現相當吻合的情形,以及全口針、功能性齒針及替代齒針的長度範圍值在各前後齡期幼蟲和雌蟲間大都具有明顯區隔的結果顯示,這56群劍線蟲的鑑定樣本中皆無發生互相混雜或存在其他形態相類似但尚未鑑定的其他劍線蟲種類,因此該8種劍線蟲內的各群雌蟲的形態測量值足以代表各該種劍線蟲的種內形態變異性範圍。在rDNA片段序列的比對結果顯示,種內各群間的ITS-1和ITS-2的序列差異度百分比值皆比種間明顯為小,其中上述屬於X. americanum group的4種劍線蟲 (X. silvaticum 無資料),其種內各群間分別都在1.64和1.81以下,而種間的差異度以X. brevicollum和X. incognitum二種間最接近,其值分別為3.54和2.91,至於在各項形態測量值上,其中尤其是體長及全口針長度上最接近的X. incognitum和X. diffusum間,其值分別達到12.22和14.58。另外X. elongatum和X. insigne的rDNA片段大小相當接近,分別為2083 和2088 bp,而其種內的ITS-1和ITS-2的值分別都在0.55和1.34及3.02和2.23以下,而二種間則分別達到32.73和42.66。由在台灣地區這8種劍線蟲雌蟲的形態鑑定結果,其形態測量值和世界其他地區的資料有不同程度的差異情形,而本研究也已將該8種劍線蟲的各齡期幼蟲及部分種類的雄蟲做一完整的形態鑑定,另外,除X. silvaticum外,其餘7種劍線蟲的rDNA片段序列資料也首次登錄至GenBank資料庫中,因此如果台灣以外地區的研究能參考此一模式,提供更詳實的幼蟲及雄蟲鑑定資料,並進行rDNA (ITS-1, ITS-2) 片段序列的差異度比較分析,只有如此方能更客觀地檢視世界各地區劍線蟲種類鑑定的正確性,並藉以充分認知其形態上的變異性。
Fifty six geographical populations of Xiphinema populations were isolated from central, south and east areas of Taiwan from 1996 to 2002. Based on the morphometrics of females, eight species were identified. X. brevicollum, X. incognitum, X. diffusum, X. oxycaudatum and X. silvaticum, which belong to the X. americanum group, and non X. americanum group, X. elongatum, X. insigne and X. hunaniense. Comparisons of the replacement ondontostyle and functional odontostyle length identified, there are 3 juvenile stages in the life cycle of X. oxycaudatum, but 4 juvenile stages for the other 7 Xiphinema species. Based on the matchable length of replacement odontostyle and functional odontostyle, and also the evident gap of replacement odontostyle and total stylet length of successive juvenile stages and adult within a population, we are confident that the examined specimens were not mixed with unidentified morphologically similar Xiphinema species. Consequently, the morphometrics of females could reflect the morphological variations in each population. The values of pairwise percentage dissimilarity of intraspecific comparisons of rDNA (ITS-1, ITS-2) sequences were lower than to that of interspecific. Among them, the intraspecific dissimilarity values of ITS-1 and ITS-2 of the above 4 X. americanum group species (no data of X. silvaticum) were below 1.64 and 1.81, respectively, and X. brevicollum and X. incognitum has the least interspecific dissimilarity (value 3.54 & 2.91). Although the morphometrics of X. incognitum and X. diffusum were most close to each other, but the dissimilarity values were 12.22 and 14.58 respectively. X. elongatum and X. insigne has similar sequence size of rDNA fragments of 2083 bp and 2088 bp, but their interspecific values reached to 32.73 and 42.66 respectively. The morphometric data of the 8 Xiphinema species found in Taiwan showed some small differences compared to reports from countries worldwide. This is the first report for the morphometrics of females, males (except for the 5 X. americanum group species) and its whole juvenile stages of the 8 Xiphinema species in Taiwan, but also the first published rDNA sequence data of those species. To decide the limitation of intraspecific and interspecific variation, more morphometric data of the females, males and juveniles, along with the rDNA sequence data from different geographical region should be added to objectively inspect the correctness of identification and to pronounce the variation of the Xiphinema species.
URI: http://hdl.handle.net/11455/31496
Appears in Collections:植物病理學系

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