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Tropical soda apple mosaic virus Identified in Solanum capsicoides in Florida

Red soda apple (Solanum capsicoides All.), a member of the Solanaceae, is a weed originally from Brazil (3). It is a perennial in southern Florida and is characterized by abundant prickles on stems, petioles, and leaves. Prickles on stems are more dense than those on its larger, noxious weed relative, tropical soda apple (Solanum viarum Dunal), and the mature red soda apple fruits are bright red in contrast to the yellow fruits of tropical soda apple (2). Virus-like foliar symptoms of light and dark green mosaic were observed on the leaves of a red soda apple in a Lee County cow pasture during a tropical soda apple survey during the fall of 2004. The appearance of necrotic local lesions following inoculation of Nicotiana tabacum cv. Xanthi nc with sap from the symptomatic red soda apple leaves suggested the presence of a tobamovirus. Tropical soda apple mosaic virus (TSAMV), a recently described tobamovirus isolated from tropical soda apple in Florida, was specifically identified by a double-antibody sandwich-ELISA (1). An additional six similarly symptomatic red soda apple plants were later collected in the Devils Garden area of Hendry County. Inoculation of N. tabacum cv. Xanthi nc with sap from each of these symptomatic plants also resulted in necrotic local lesions. Sequence analysis of the TSAMV coat protein (CP) gene amplified from total RNA by reverse transcription (RT)-PCR with a mixture of upstream (SolA5′CPv = 5′-GAACTTWCAGAAGMAGTYGTTGATGAGTT-3′; SolB5′CPv = 5′-GAACTCACTGARRMRGTTGTTGAKGAGTT-3′) and downstream (SolA3′CPvc = 5′-CCCTTCGATTTAAGTGGAGGGAAAAAC-3′; SolB3′CPvc = 5′-CGTTTMKATTYAAGTGGASGRAHAAMCACT-3′) degenerate primers flanking the CP gene of Solanaceae-infecting tobamoviruses confirmed the presence of TSAMV in all plants from both locations. Nucleotide and deduced amino acid sequences of the 483-bp CP gene were both 98 to 99% identical to the original TSAMV CP gene sequences in GenBank (Accession No. AY956381). TSAMV was previously identified in tropical soda apple in these two locations in Lee and Hendry counties and three other areas in Florida (1). Sequence analysis of the RT-PCR products also revealed the presence of Tomato mosaic virus in the plant from Lee County. To our knowledge, this represents the first report of natural TSAMV infection of any host other than tropical soda apple and suggests that TSAMV may be more widely distributed in solanaceous weeds than initially reported.

References: (1) S. Adkins et al. Plant Dis. 91:287, 2007. (2) N. Coile. Fla. Dep. Agric. Consum. Serv. Div. Plant Ind. Bot. Circ. 27, 1993. (3) U.S. Dep. Agric., NRCS. The PLANTS Database. National Plant Data Center. Baton Rouge, LA. Published online, 2006.