|Wallis, Chris - PENN ST. UNIV.|
|Gildow, Fred - PENN ST. UNIV.|
Submitted to: American Phytopathological Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: March 1, 2004
Publication Date: June 20, 2003
Citation: Schneider, W.L., Stone, A.L., Wallis, C., Sherman, D.J., Shank, K., Damsteegt, V.D., Gildow, F. 2003. Host adaptation and memory in plum pox potyvirus populations. Phytopathology 93:S100. Technical Abstract: Plum Pox Potyvirus has recently been found in the United States and Canada. Attempts to eradicate the disease have prompted considerable research into alternative hosts and possible reservoirs of the virus in nature. In preliminary experiments, PPV was inoculated onto a number of herbaceous hosts. PPV showed dramatic improvement in infectivity, symptom development and viral titer with continued passage on the same host. To investigate possible adaptation in new hosts, PPV from peach was inoculated onto peas by aphid and mechanical means, and passaged 10 consecutive times using the same method. RNA samples were extracted after each passage. The infectivity, symptom development and titer "improvement" phenotypes were observed again, suggesting adaptation to peas was occurring. The populations from infected peas were back-inoculated onto peach to determine if adaptation to pea reduced infectivity in peach. The pea-passaged PPV populations lost infectivity on peach with continued passage, but never completely lost the ability to infect peach. Pea-passaged PPV populations were sequenced to find potential adaptive mutations. Four mutations were identified, one in the HC-Pro gene, one in the 6k gene, and two in the NIB (replicase) gene. Initial molecular analysis of the passaged populations indicates that a percentage of the PPV population in peas maintains the peach-adapted, non-mutated sequence, even after a number of passages on peas. This could be evidence of memory in PPV populations, i.e., the ability to maintain individual RNAs in the population that are less fit in the current environment but better adapted to a previous selective environment.