ISHS Acta Horticulturae 94: XI International Symposium on Fruit Tree Virus Diseases
STUDIES FOR THE CHARACTERIZATION OF PRUNE DWARF VIRUS STRAINS |
| Authors: | L. KUNZE, M.F. CLARK, C. L. FLEGG |
| Abstract:
Within the prune dwarf virus (PDV) a large variation among different isolates can be observed with regard to the symptoms of herbaceous host plants (WATER-WORTH and FULTON, 1964). The isolates can be identified as PDV by serology very well, but the differentation of PDV strains is not yet possible by this method. For this reason we tested some other methods to differentiate two German isolates of PDV (Hattersheim 13/25 and 15/28) from other PDV isolates already described. These isolates belonged to the ‘virus B’ (FULTON, 1958), the ‘virus S’ (CROPLEY et al., 1964), and the yellow mottle strain (RAMASWAMY and POSNETTE, 1972). Both the German isolates originated from sour cherries with dwarfing and necrotic leaf mottle. These symptoms were caused by the isolated virus as could be shown by retransmission of one German isolate from Buttercup squash (Cucurbita maxima Duch.) via peach seedling to sour cherry. The differences in the reactions of herbaceous hosts were not sufficiently reliable for the characterization of virus strains because the symptoms varied considerably under the influence of environmental conditions. As PDV is a multicomponent virus the purified isolates were centrifugated in a sucrose density gradient and scanned photometrically to compare the resulting absorption profiles (SDG profiles). Two types of SDG profiles were found, but the types of profiles did not correspond with the relations between the isolates (Fig. 1). Therefore it is not possible to distinguish PDV strains on the basis of the proportion of their components tested by sucrose density gradient centrifugation. In the free boundary electrophoresis in an apparatus similar to that described by VAN REGENMORTEL (1972) the components of PDV migrated homogeneously as found by HALK and FULTON (1978). Differences in the electrophoretic mobility were demonstrated, however, between some of the investigated isolates. According to the relative mobility (compared with phenol red) in the sucrose density gradient electrophoresis three groups of PDV isolates could be differentiated. This arrangement was confirmed by immunoelectrophoresis. Furthermore it corresponded to the types of the disease caused in cherries by the isolates (Table 1). Among the | |
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