Viral reservoir capacity of wild Prunus alternative hosts of plum pox virus through multiple cycles of transmission and dormancy

Authors: Collum, Tamara - Tami; Stone, Andrew; Sherman, Diana; DAMSTEEGT, VERNON - Retired ARS Employee; SCHNEIDER, WILLIAM - F1k9; Rogers, Elizabeth

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/21/2021
Publication Date: 1/20/2022
Citation: Collum, T.D., Stone, A.L., Sherman, D.J., Damsteegt, V.D., Schneider, W.L., Rogers, E.E. 2022. Viral reservoir capacity of wild Prunus alternative hosts of plum pox virus through multiple cycles of transmission and dormancy. Plant Disease. 106:101-106. 10.1094/PDIS-04-21-0802-RE.
DOI: https://doi.org/10.1094/PDIS-04-21-0802-RE

Interpretive Summary: Plum pox virus (PPV) causes a serious disease in stone fruit trees including peaches and plums. The virus is spread by aphid insect vectors or through grafting with infected plant material. Efforts to control the spread of the virus rely on the identification of wild plants near stone fruit orchards that can also be infected by PPV. These reservior hosts could serve as sources of virus for reinfection of the stone fruit crops. In greenhouse studies, PPV has been shown to infect many different plant species including wild woody trees and small, annual plants. Due to their long life and prevalence in stone fruit growing regions, wild woody perennial trees are of particular concern as potential PPV sources. In this study, three wild species related to cultivated stone fruits (western choke cherry, black cherry, and wild American plum) were grown in a greenhouse and evaluated for their ability to be infected with PPV by aphid transmission, as well as their potential to serve as sources of virus for aphid transmission to additional trees, either wild species or peach. Trees were further tested for PPV accumulation over five cycles of 3-4 months of growth and 2-3 months of cold treatment that was used to mimic the winter dormancy period. The three wild species had differences in their ability to maintain a PPV infection and serve as a source of virus for aphid infection of additional trees. The results indicate that American plum has the greatest potential to act as a reservoir host for PPV, while black cherry and western choke cherry are unlikely to be significant sources of PPV in nature. These results will help inform detection and control efforts for PPV.

Technical Abstract: Plum pox virus (PPV) is a significant pathogen of Prunus worldwide and is known for having a broad experimental host range. Many of these hosts represent epidemiological risks as potential wild viral reservoirs. A comparative study of the PPV reservoir capacity of three commonly found native North American species, western choke cherry (P. virginiana var. demissa), black cherry (P. serotina), and American plum (P. americana) was conducted. Pennsylvania isolates of PPV-D were transmitted from the original host peach (P. persica cv. GF305) to all three species. Viral accumulation and transmission rates to alternative hosts and peach were monitored over the course of five vegetative growth and cold induced dormancy (CID) cycles. The three alternative host species demonstrated differences in their ability to maintain PPV and the likelihood of transmission to additional alternative hosts or back transmission to peach. Western choke cherry had low (5.8%) initial infection levels, was not transmissible to additional western choke cherry, and transmission to peach was only possible before the first CID cycle. Black cherry had intermediate initial infection levels (26.6%) but did not maintain high infection levels after repeated CID cycles. Conversely, American plum had a high level (50%) of initial infection and maintained moderate levels (15-25%) of infection and transmission to both American plum and peach through all five cycles of CID. Our results indicate that American plum has the greatest potential to act as a reservoir host for Pennsylvania isolates of PPV-D.