USE OF AN IMMUNOCAPTURE-POLYMERASE CHAIN-REACTION PROCEDURE FOR THE DETECTION OF GRAPEVINE VIRUS-A IN KOBER STEM GROOVING-INFECTED GRAPEVINES

Reliable and highly sensitive detection of grapevine virus A (GVA) in grapevine leaf tissue by reverse transcription-initiated polymerase ch ain reaction was achieved after enrichment and partial purification of the virus from grapevine crude sap by an immunocapture (IC) procedure . In comparison with ELISA the gain of sensitivity was estimated up to 1000-fold in grapevine mature leaf tissue. Using IC-reverse transcrip tion polymerase chain reaction (IC-RT-PCR), GVA could be detected in v ery young grapevine tissues where the virus titre was largely below th e detection limit of ELISA. The comparison of IC-RT-PCR and biological indexing results for about 60 grapevine accessions revealed a good co rrelation between the presence of GVA and the development of Kober ste m grooving (KSG) symptoms in the specific indicator rootstock Kober 5B B. Moreover, the elimination of KSG by heat treatment in two Vitis vin ifera cultivars, Savagnin rose and Servant, was accompanied by the los s of detection of GVA by PCR, thus providing further argument for the involment of GVA in the aetiology of KSG.