First report of Pepper mild mottle virus and Tobacco mild green mosaic virus infecting pepper in Panama

Pepper (Capsicum annuun) represents an important crop in Coclé, Herrera, and Veraguas central regions of Panama. The estimated total cultivated area is 180 ha and the approximate production is 2685 tonnes over the whole country. In February 2008, noticeable bubbling, curling, green-yellow mosaic, deformation (Figs. 1 and 2a), ringspot, necrosis of leaves (Figs. 2b), and fruits distortion (Fig. 3) were observed in open-field crops from these regions.

To verify the identity of the disease, three symptomatic plants from three fields of these regions were selected and analyzed by DAS-ELISA using specific antibodies to Broad bean wilt virus-1 (BBWV-1), Cucumber mosaic virus (CMV), Pepper mild mottle virus (PMMoV), Potato virus Y (PVY), Tobacco etch virus (TEV), Tobacco mild green mosaic virus (TMGMV), Tobacco mosaic virus (TMV), Tomato mosaic virus (ToMV), and Tomato spotted wilt virus (TSWV) (Loewe Biochemica, Sauerlach, Germany). All these plants were representative of each region. CMV/PMMoV/PVY/TMGMV multiple infection was detected in one plant. The other plants were also positive to CMV/PMMoV/TMGMV. No differences in symptom expression were observed, except for the infected plant with four viruses, which also showed necrotic symptoms. To confirm these results, total RNA was extracted from these plants and tested by RT-PCR with primers specific designed to amplify a region of the coat protein gene of CMV (CMV-D 5′-CCTCCGCGGATGCTAACTT-3′ and CMV-R 5′-CGGAATCAGACTGGGAGCA-3′), PMMoV (Takeuchi et al., 2005), TMGMV (Cohen et al., 2001), and universal potyvirus degenerate primers (POTY1 5′-ATGGTKTGGTGYANTGANAA-3′ and POTY2 5′-TDHGCWGCNGCYTTCATYT-3′). Amplicons of the expected size were generated from symptomatic plant tissue, but were not produced from healthy plants or the water used as negative controls. RT-PCR products were purified and directly sequenced. BLAST analysis of CMV (GenBank Accession No. EU930200), PMMoV (EU934033), potyvirus-PVY (EU934034), and TMGMV (EU934035) sequences showed 98%, 99%, 93%, and 98% nucleotide identity, respectively, with reference sequences deposited in the NCBI database.

CMV and PVY are transmitted by aphids (Brunt et al., 1996); whilst, PMMoV and TMGMV are seed-borne in pepper (Córdoba et al., 2006). The aphid-assisted transmission and infected seeds may be a concern regarding long distance spread of these viruses, and should be considered in the disease management strategies. To our knowledge, this is the first report of PMMoV and TMGMV in Panama.