PCR detection of viruses of the grapevine leafroll complex
Van der Merwe, M
ARC Plant Protection Research Institute
Kasdorf, G G F
The control of the grapevine viruses is dependent upon the effectiveness of clean stock programmes where virus-free propagation material is used in nurseries and vineyards. The symptoms of leafroll and rugose wood can resemble symptoms caused by mechanical damage, thereby complicating visual diagnosis. The need of diagnostic tools for easy, broad range and highly sensitive screening of large numbers of grapevine stocks is particularly felt in the frame of certification and sanitary selection programmes currently operating as well as in replanting programmes.
Virus detection methods such as enzyme-linked immunosorbent assay (ELISA) and immunosorbent electron microscopy (ISEM) have limitations with regard to sensitivity. In grapevines where viruses are distributed unevenly throughout the plant and viral titers vary considerably according to seasonal influences it is important to have a more sensitive detection method. Polymerase chain reaction (PCR) amplification can be used as a considerably more sensitive detection method for viruses at lower concentrations.
The long-term objective of this project is to have PCR detection for all important grapevine viruses for use in diagnostic services. (The project was originally aimed only at the viruses of the leafroll complex, but has since been expanded to include all the important viruses of the grapevine). The short-term objectives are to look at the more important viruses like grapevine virus A (GVA), grapevine virus B (GVB) and grapevine leafroll-associated virus-1 (GLRaV-1) and to develop a PCR detection method for these viruses first.
PCR detection methods have been developed for some of the important grapevine viruses such as grapevine leafroll associated virus 3 (GLRaV-3), but more work needs to be done before PCR detection of all the important viruses will be available. Although some of these tests are available elsewhere, it is very important to have PCR detection methods that have been developed, optimised and tested on our local strains as the variance between strains seems to be significant. This could lead to false negatives when testing with primers that have been developed elsewhere.
Van der Merwe, M, Kasdorf, G G F and Pietersen, G. 2000. The use of PCR for the detection of grapevine leafroll-associated virus 3. Paper presented at the 8th Congress of the International Council for the Study of Virus and Virus-like Diseases of the Grapevine, Adelaide, Australia.