ARS | Publication request: Genetic diversity of Pepino mosaic virus in the U.S. and identification of a tomato infecting strain capable of inducing disease on potato

Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: May 1, 2010
Publication Date: June 20, 2010
Repository URL: http://www.isppweb.org/ICPUE/
Citation: Ling, K. 2010. Genetic diversity of Pepino mosaic virus in the U.S. and identification of a tomato infecting strain capable of inducing disease on potato. Meeting Proceedings. p. 82.

Technical Abstract: Growers were once reluctant to remove Pepino mosaic virus (PepMV)-infected tomato plants because its effect on yield was considered mild. Pepino mosaic has now become an endemic disease problem on greenhouse tomatoes in the U. S. Recently, viroids (i.e., Tomato chlorotic dwarf viroid - TCDVd) were identified to naturally infect tomatoes. Mixed infection of PepMV and TCDVd appeared to result in more dramatic disease symptoms on tomato. The objectives of the present study were to evaluate the host range via mechanical inoculation, to conduct molecular characterization of disease causing agents on various alternative host plants, and to determine whether the disease was caused by a synergistic effect of PepMV and TCDVd or involved some other unidentified components. Four field isolates were selected for host range study with 38 plant species in 9 families. In addition to the detail examination of disease symptoms exhibited on the indicator plants, appropriate detection methods (ELISA or RT-PCR) were employed to determine the PepMV and/or viroid infection. Infectivity of PepMV and/or viroid on the alternative host plants was confirmed through back-inoculation onto tomato ‘Money Maker’. Nucleotide sequences obtained through direct sequencing of PCR amplicons for PepMV or Pospiviroid were analyzed against GenBank database. The results showed that in addition to the prevalent EU-like genotype, the CH2 genotype has now expanded to other states in the U.S. A tomato-infecting EU-like strain was capable of inducing disease symptoms on potato upon mechanical inoculation. Although the original pepino strain of PepMV was capable of infecting potato, to our knowledge this is the first time that a tomato strain of PepMV was demonstrated to infect potato. These results indicated that tomato growers in the U.S. are facing difficulties in effectively managing their viral disease problems due to the emergent of new PepMV genotype (CH2) and the introduction of viroids.