Characterization of a new potyvirus isolated from asclepias (Asclepias curassavica L.) showing mosaic symptom
| Autor: | Zi-Yi Zhu, 朱子逸 |
|---|---|
| Rok vydání: | 2011 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 99 Asclepias (Asclepias curassavica L.) was a perennial herb plant of the family Asclepiadaceae, that was introduced from America area, and was toxic in whole plant. The diseased plants of asclepias showing mosaic symptom was found at Yi-Lan area, Taiwan in 2009. The flexuously filamentous viral particles from leaf saps of mosaic asclepias were observed by electron microscopy, and the length of viral particles was 750-800 nm. The flexuous virus was successfully isolated by mechanical inoculation on Chenopodium amaranticolor and the healthy seedlings of asclepias showed the same mosaic symptom after back inoculation. Thermal inactivation point of the virus was 55-60℃, longevity in vitro was 2-3 days at 25℃ and four months at -75℃, dilution end point was 10-4-10-5. It had a very narrow host range restricted to four species in chenopodiaceous and asclepiadaceous plants among 44 tested plant species belonging to 11 families. The virus was transmissible by aphis nerii as a vector with non-persistent type, and the transmission rate was 16.7%. Seed transmission was not observed in research. The typical pinwheel-shaped and laminated inclusion bodies of potyviruses infection were observed in diseased leaves of asclepias showing mosaic symptom by electron microscopy. An antiserum with a titre of 4096 by ring interface precipitin test was obtained by immunizing a New Zealand white rabbit with the purified virions. In sodium dodecyle sulfate (SDS)-agar gel double diffusion, western blotting and Indirect enzyme-linked immunospot assay the antiserum against the asclepias flexuous virus reacted strongly with its homologous antigens, and reacted with 21 other potyviruses in western blotting and Indirect enzyme-linked immunospot assay. Coat protein (CP) with a molecular weight of 30 kDa was detected by SDS-polyacrylamide gel electrophoresis (SDS-PAGE) and western blotting. In order to further characterize the virus at the molecular level, coat protein gene of the asclepias virus isolate was cloned, sequenced and analyzed. A sequence of 1399 nucleotides (nts) was obtained and the percentage of nucleotides identities of CP gene and 3′ non-coding region (NCR) were less than 69.5% and 48.6%, comparing to 15 potyviruses, respectively. Similarly, the percentage identity of CP amino acid sequence to those of 15 other known potyviruses were all below 71.5%. The virus was identified as a new potyvirus species on the basis of its particle morphology and size, physical properties, cytopathology, serological characteristics and identity of nucleotide and amino acid sequence of CP. The name Asclepias mosaic virus(AscMV) was provisionally proposed. It is the first report about a potyvirus infection on Asclepias curassavica in the world. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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