FIRST MOLECULAR EVIDENCE OF THE OCCURRENCE OF A PEA MOSAIC STRAIN OF BEAN YELLOW MOSAIC VIRUS IN VERBENA × HYBRIDA
Verbena × hybrida is an ornamental annual used in rock gardens, as an edging plant, and in hanging baskets. It comes in a variety of colors and grows approximately 6 to 10 inches tall. Verbena 'Lavender Shades' plants from California showing leaf mosaic symptoms tested positive for potyvirus in an antigen-coated plate ELISA using our potyvirus broad spectrum reacting PTY-1 monoclonal as the detecting antibody. The virus was transmitted mechanically to Nicotiana benthamiana from infected verbena plants by sap inoculation. Further serological analysis with our panel of Bean yellow mosaic virus (BYMV)-specific, BYMV-subgroup, and potyvirus cross-reactive monoclonal antibodies suggested that the verbena potyvirus might be a member of the BYMV subgroup. Total RNA extractions from infected verbena and tobacco leaves were used in RT-PCR assays with generic potyvirus-specific primers, which amplify highly conserved 700bp or 1600bp fragments from the 3' terminus of most potyviruses. This region includes the potyviral coat protein (CP) and the 3' non-coding region (3'NCR). The PCR amplified fragments were cloned using standard TA cloning procedures and sequenced using dye-terminator chemistry. The cloned nucleotide and putative coat protein amino acid sequences from the infected verbena and tobacco plants were compared to the corresponding regions of other potyviruses. Amino acid comparison of the CP region of the verbena potyvirus showed 95-96% identity to four pea mosaic strains (PMV) of BYMV, 85-89% identity to 20 other strains of BYMV, 74-76% identity with six strains of Clover yellow vein virus (CYVV), and only 50-64% identity with 28 other potyviruses. Additionally, similar pairwise analysis of the 3'NCR of the verbena potyvirus showed 98-99% identity to PMV strains, 81-94% to other BYMVs, 68-75% to CYVVs, and 52-64% with other potyviruses. These and other phylogenetic analysis of the CP and 3'NCR sequences of PMV, BYMV, CYVV and other potyviruses confirmed the designation of the verbena potyvirus isolate as a pea mosaic strain of BYMV.
Guaragna, M.A., Jordan, R. and Putnam, M.L. (2006). FIRST MOLECULAR EVIDENCE OF THE OCCURRENCE OF A PEA MOSAIC STRAIN OF BEAN YELLOW MOSAIC VIRUS IN VERBENA × HYBRIDA. Acta Hortic. 722, 305-312
Potyvirus, RT-PCR, monoclonal antibody