VIEW ARTICLE

Ecology and Epidemiology

Differentiation of Pseudorecombinants of Two Cucumber Mosaic Virus Strains by Biological Properties and Aphid Transmission. Thomas A. Zitter, Department of Plant Pathology, Cornell University, Ithaca, NY 14853; Dennis Gonsalves, The New York State Agricultural Experiment Station, Geneva 14456. Phytopathology 81:139-143. Accepted for publication 10 August 1990. Copyright 1991 The American Phytopathological Society. DOI: 10.1094/Phyto-81-139.

Pseudorecombinants prepared from the RNAs of two distinct strains of cucumber mosaic virus (CMV) were studied to determine reasons for differences in symptom severity and transmission efficiency by Aphis gossypii. Strain CMV-FNY, readily transmitted to and from summer squash, and CMV-SNY, a moderately transmitted strain, were used. Genomic RNAs 1, 2, and 3 of CMV-FNY and CMV-SNY were used to construct pseudorecombinants in all combinations. Symptom severity ratings were higher when RNA 1 from CMV-FNY was present than when recombinants were constructed with RNA 1 from CMV-SNY. The average number of days required to reach 100% symptom expression was lower when RNA 1 from CMV-FNY was present. Maximum aphid transmission and symptom severity occurred for the combination of RNAs 1 and 3 from CMV-FNY (e.g., F-S-F), followed by the combinations of F-F-S, S-S-F, and S-F-S. Results suggest that RNA 1, associated with virus replication, is most important in achieving maximum transmission and symptom severity. RNA 3 appears to have an intermediate role in aphid transmission and symptom expression.