碩士 / 國立臺灣大學 / 植物病理學研究所 / 89 / Members of the genus Potyvirus, family Potyviridae are the largest group of filamentous plant viruses. Dasheen mosaic potyvirus (DsMV), a member of the genus, is a well-known virus of aroid plants around the world. In 1998, three isolates of DsMV were obtained from several aroid plants groth in Taiwan by our laboratory. All of them were partially sequenced during 1998 to 1999, which including the region of NIb 3’end, CP and 3’ UTR. Two DsMV isolates from calla lily were designated as DsMV-ZAE (from Zantedeschia aethiopica) and DsMV-ZAN (from Zantedeschia spp.). To understand the molecular characteristics and sequence differences between these two isolates, cDNA clones were obtained from RT-PCR products of total RNAs of infected plants. DR4 and DR4a primers located in NIb region and DF4 primer located in NIa region were designed and used for cloning. The RT-PCR products of DsMV-ZAN (1381 nts) and DsMV-ZAE (1384 nts) were then cloned and sequenced. These new sequence data were assembled with previously known sequences, and thus we got the sequence of 3060 nts and 3064 nts, respectively, including the 3’ end of NIa, NIb gene, CP gene, and 3’UTR. Amino acid sequence analysis of NIb gene showed that DsMV-ZAN shared 96% similarity to DsMV-ZAE. These two isolates shared 96% sequence similarity with DsMV-Ch isolate. In addition, the similarities of NIb sequences between DsMV and other potyviruses are within 69% and 71%, but DsMV has 84% similarity to Soybean mosaic virus (SMV). Phylogenetic analyses of the amino acid sequences of CP and NIb proteins gave similar results that reflected the relationship between DsMV and SMV more closer than others.
The unpublished potyvirus of aroid plants, Zantedeschia mosaic virus (ZaMV), was found in calla lilies in Taichung area in 1998. There were three isolates obtained during 1998 and 1999. Cloning and sequencing of ZaMV clones showed a 1.6-kb sequence that contains partial of NIb gene, CP gene, and 3’UTR region. Sequence analysis of ZaMV isolates shared 99% similarity. To obtain more sequence data of ZaMV, cDNA clones were obtained by RT-PCR from total RNAs extracted from Zantedeschia spp. cv. ‘Super Gold’. Based on the known sequences of ZaMV, specific primers were designed, and degenerate primers were designed from conserved region of potyvirus genome. RT-PCR fragments were cloned and sequenced. In addition, the previous 1.6-kb clones of ZaMV-SG from 1999 were sequenced and the data were merged with data of other new clones by GCG program. A 7857-nts sequence including HC-Pro C-terminal, P3, CI, NIa, NIb, CP genes, and 3’UTR (exclude poly(A) tail) was obtained. Deduced amino acid sequences of these genes by GCG program were found similar to the conserved regions of potyviruses. The similarities of CP sequences between ZaMV and other potyviruses are from 58% to 71%, but it shared 93% similarity with Konjak mosaic virus (KoMV) that was published in Japan. The highly conserved genes, NIb and CI, showed about 70 % similarity between ZaMV and other potyviruses. The P3 is the most variable gene product sequenced so far, only 32% to 49% sequence similarities between ZaMV and other potyviruses. Generally speaking, taxonomy of potyviruses is usually according to the CP sequence similarity. From result of sequence analysis, we may assume that ZaMV and KoMV are the same virus species. Whereas two aroid-infecting viruses, DsMV and ZaMV, are unrelated according to the results of phylogenetic analysis.
| Identifer | oai:union.ndltd.org:TW/089NTU00364003 |
| Date | January 2002 |
| Creators | Hu, Wen-Chi, 胡文綺 |
| Contributors | Chang, Ya-Chun, 張雅君 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 77 |
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