RESUMO
In host range investigations with 152 plant species of 37 families, 96 species from 28 families proved to be experimentally susceptible to asparagus virus 2 (AsV 2). From these, 82 species of 26 families were systematically infectible and 14 species of 10 families only locally. Most frequently were symptomless systemic infections. Of 86 species, their susceptibility for AsV 2 was unknown before. The number of families that contant experimental hosts of the virus increased from 11 to 33. Transmission of AsV 2 was neither possible with Myzus persicae nor with Cuscuta californica or C. campestris. AsV 2-infected mother plants transmitted the virus by about 40 per cent to their seedings. Open-pollinated plants, not infested by AsV 2, showed 3 to 22 per cent of infected seedings. Mechanical back-transmission of AsV 2 from test plants to asparagus succeeded only in one case. The properties of the virus in vitro were as follows: thermal inactivation point between 64 and 66 degrees C, dilution end point between 10(-3) and 10(-4), stability in sap, stored at room temperature, up to 96 hours. Serological investigations demonstrated no relationship to the virus to numerous other viruses. An antiserum with a titer of 1 to 16 was useful for the detection of AvV 2 in asparagus sap. Electron microscopical investigations proved for the virus isometric particles for the first time. In negatively stained preparations they had a diameter of 27 nm.
