A modified green-grafting technique for large-scale virus indexing of grapevine (Vitis vinifera L.)

A modified method of green-grafting was investigated for use in viral indexing of grapevine stock. Cabernet franc and Cabernet sauvignon scions infected with grapevine leafroll-associated virus 3 (GLRaV3) were cleft-grafted on to virus-free indicator rootstocks LN33 and C. sauvignon, and were maintained in polystyrene containers containing vermiculite soaked with Huglin and Julliard solution. Using this method plants could be transferred to soil 3-4 weeks following grafting. Leafroll symptoms: reddening of leaves, leaf rolling, and interveinal discolouration, were scored at 3-4 weeks and again at 12 weeks. Double antibody sandwich-enzyme linked immunosorbent assay (DAS-ELISA) was used to validate the visual symptoms of disease. At both times it was clear that C. sauvignon was a more sensitive indicator of GLRaV3 than LN33, with 80% of grafts showing symptoms at 3-4 weeks and 90% showing symptoms at 12 weeks. The results indicate that the technique described here is effective and suitable for large-scale indexing of grapevine stock for viral contamination.