Insights on the directional movement of Prunus necrotic ringspot virus between peach and wild Prunus species

Peach (Prunus persica) is an economically important crop in the southeastern United States. Prunus necrotic ringspot virus (PNRSV) is a pollen-borne pathogen that affects peaches and other stone fruits worldwide. Wild Prunus spp. in the proximity of peach orchards have the potential to serve as reservoirs of PNRSV. To better understand virus movement at the crop-wild flora interface, we tested peach trees for PNRSV via RT-PCR, sequenced the coat protein genes of PNRSV isolates, and compared them to PNRSV CP sequences from nearby wild black cherry (Prunus serotina) trees. Additionally, we collected bloom time data from P. persica and P. serotina over three seasons to determine if the bloom periods of these species overlap. PNRSV sequence analysis shows the separation between PNRSV isolates from peach, which were highly variable, and wild black cherry, which formed a distinct monophyletic clade with the exception of a single isolate. Bloom time data suggest a temporal separation of flowering periods between the two species, with peach trees going through that phenophase before wild black cherries. Taken together, these results suggest that if movement of PNRSV occurs between peach and wild black cherry at this location, we hypothesize based on our data that it would occur predominantly in one direction: from peach to wild black cherry.