ISHS Acta Horticulturae 657: XIX International Symposium on Virus and Virus-like Diseases of Temperate Fruit Crops - Fruit Tree Diseases
FIRST DETECTION AND MOLECULAR CHARACTERISATION OF PPV-M STRAINS IN PLUM ORCHARDS IN SOUTH-WESTERN GERMANY |
| Authors: | W. Jarausch, A. Baβler, N. Molla, G. Krczal |
| Keywords: | sharka, RT-PCR, ELISA, epidemiology, Prunus, Germany |
| Abstract:
Although sharka disease caused by Plum pox virus (PPV) is widespread in German stone fruit growing areas since many years, little was known about the epidemiology of PPV in Germany. Therefore, we conducted in 2000 to 2003 new surveys in the major stone fruit growing regions of South-western Germany to evaluate the actual distribution of different PPV strains. More than 200 leaf samples were taken in summer from plum, peach and apricot in the orchards as well as from wild Prunus species. All samples were first tested by DAS-ELISA with polyclonal antibodies and then by RT-PCR with the primers P1/P2. PPV strain determination was done serologically by DASI-ELISA with the PPV-D specific monoclonal antibody 4D and the PPV-M specific monoclonal antibody M. Molecular strain typing was done either by RT-PCR-RFLP or by using PPV-D specific primer PD and PPV-M specific primer PM. Serological and molecular strain typing gave consistent results in all cases where both methods yielded positive reactions. Whereas the PPV-D strain was found in the majority of samples PPV-M strains were detected for the first time in three regions of South-western Germany. In total, 35 samples were found to be infected with PPV-M. PPV-M was found in the two important stone fruit growing regions Ortenau and Kaiserstuhl as well as in a region near Stuttgart in Baden-Württemberg. PPV-M was only detected in plum but not in peach which was also grown in one of the regions. Different cultivars of plum were found to be infected. In the same cultivar planted in the same orchard PPV-D and PPV-M strains were observed. In this case, leaf symptoms of PPV-M were more severe than symptoms of trees infected with PPV-D. Four PPV-M isolates were further characterized. A 1,2 kb fragment covering the 3’-end of the NIb gene and the coat protein gene was amplified by RT-PCR and directly sequenced. The sequence analysis confirmed that the isolates were of PPV-M type. The homologies of the sequences ranged from 95% to 99%. | |
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