Survey of Prunus necrotic ringspot virus in rose and its variability in rose and Prunus spp.

A survey for viruses in rose propagated in Europe resulted in detection of only Prunus necrotic ringspot virus (PNRSV) among seven viruses screened. F our percent of cut-flower roses from different sources were infected with P NRSV. Progression of the disease under greenhouse conditions was very slow, which should make this virus easy to eradicate through sanitary selection. Comparison of the partial coat protein gene sequences for three representa tive rose isolates indicated that they do not form a distinct phylogenetic group and show close relations to Prunus spp. isolates. However, a comparis on of the reactivity of monoclonal antibodies raised against these isolates showed that the most prevalent PNRSV serotype in rose was different from t he most prevalent serotype in Prunus spp. All of the 27 rose isolates teste d infected P. persica seedlings, whereas three of the four PNRSV isolates t ested from Prunus spp. were poorly infectious in Rosa indica plants. These data suggest adaptation of PNRSV isolates from Prunus spp., but not from ro se, to their host plants. The test methodologies developed here to evaluate PNRSV pathogenicity in Prunus spp, and rose could also help to screen for resistant genotypes.