ISHS Acta Horticulturae 110: V International Symposium on Virus diseases of Ornamental Plants
IDENTIFICATION OF TWO ISOMETRIC VIRUSES IN POINSETTIAS |
| Authors: | R. Koenig, D.E. Lesemann |
| Abstract:
In recent years we have received repeatedly poinsettia plants (Euphorbia pulcherrima Wild.) showing pronounced mosaic symptoms and containing rather large numbers of isometric virus particles. The occurrance of isometric virus particles in poinsettias has recently also been described in the United States (Fulton et al., 1978, Gardner et al., 1978). Fulton and Fulton (1980) proposed the name poinsettia mosaic virus (PoiMV) for a virus which they transmitted from poinsettias to Euphorbia cyathophora J. Murr. Purified preparations from our poinsettias yielded two virus containing fractions in sucrose density gradient centrifugation sedimenting at about 53 and 115 S. Both fractions reacted strongly and without spur formation with Fulton's antiserum to PoiMV. Apparent discrepancies in the results obtained in screening tests with ELISA and the Derrick method of immuno-electronmicroscopy were explained by the presence of a second virus in our virus preparations. This virus for which the name poinsettia cryptic virus (PoiCV) is proposed sedimented as a single component at about 120 S. Its concentration in poinsettias is about 700 times lower than that of PoiMV. In immuno-electrophoresis at neutral pH it migrates more slowly towards the anode than PoiMV. PoiMV and PoiCV did not react with each others antisera nor with antisera to more than 50 other isometric viruses including como-, cucumo-, nepo-, tombus-, tymo- and non-classified viruses. With the agar gel double diffusion test PoiMV was detected in 85% of leaf samples obtained from growers in many parts of Germany. Their planting material usually originated from abroad. With ELISA or the Derrick method even 95% of the samples proved to be infected with PoiMV. PoiMV apparently produces mosaic symptoms only at certain times of the year and under conditions which are not clearly defined yet. PoiCV was detected in all leaf samples tested so far. It is detected most reliably with the Derrick method of immuno electronmicroscopy. The agar gel double diffusion test usually fails with this virus. A newly bred German poinsettia variety was free of PoiMV, but did contain PoiCV which is possibly seed transmitted. A detailed description of our results will be given in a forthcoming paper by Koenig and Lesemann (1980) and by Koenig, Lesemann and Huth (manuscript in preparation). | |
Download Adobe Acrobat Reader (free software to read PDF files) | |
