Ribes host range and erratic distribution within plants of blackcurrant reversion associated virus provide further evidence for its role as the causal agent of reversion disease

Abstract

SummaryReversion is the most important disease of blackcurrant crops world‐wide yet, despite research over more than 70 yr, the causal agent of this disease has not been identified. We reported recently the isolation of a new virus from reverted blackcurrant which had a very close association with the two recognised forms of blackcurrant reversion disease, and was detected in vector gall mites from reverted plants and in plants on which such mites had fed (Lemmetty et al., 1997). These data suggest that this virus, tentatively called blackcurrant reversion associated virus (BRAV), may be the causal agent of reversion disease. We now report the detection of BRAV by immuno‐capture reverse‐transcriptase PCR (IC‐RT‐PCR) in redcurrant and in the wild species, Ribes spicatum and R. alpinum, other known hosts of the reversion agent, but not in the non‐host, gooseberry, graft‐inoculated with scions from reverted blackcurrant plants. We also demonstrate the erratic distribution of BRAV in reversion‐affected blackcurrant plants, another characteristic of the reversion agent. Taken together with our earlier findings, these new data add further support to the suggestion that BRAV is the causal agent of reversion disease. We also report how changes to the various parameters of sample preparation and of the IC‐RT‐PCR protocol affect the sensitivity of BRAV detection.