Archivio Journal of Plant Pathology

Abstract:

The tree tomato (Solanum betaceum Cav.) is an important edible fruit crop from the family Solanaceae that is native to South America. In 2014-2015 mosaic and necrotic symptoms on young leaves and stems were observed on tree tomato plants in Azuay provinces of Ecuador. Based on the type of symptoms, infection by a tospovirus was suspected. The presence of Tomato spotted wilt virus (TSWV, genus Tospovirus, family Bunyaviridae) was ascertained in symptomatic tissue by triple antibody sandwich (TAS)-ELISA using specific antibodies (Agdia, USA). TSWV was confirmed by RT-PCR using total RNA isolated from ELISA positive samples with the RNeasy Plant Mini kit (Qiagen). DNA fragments of ca. 800 bp were amplified using degenerate universal tospovirus primers (Chu et al., 2001). A PCR product was sequenced (Macrogen, Seoul, Korea) and the sequence was deposited in GenBank as accession No. KP772268. Sequence analysis (BioEdit v. 7.05) of TSWV isolate Ecuador with other tospovirus isolates showed 99.5% and 99.1% identity at the nucleotide and amino acid levels, respectively. A phylogenetic tree based on nucleotide sequences constructed using MEGA version 4.1 revealed a clustering of TSWV-Ecuador with TSWV-wt from Japan (AB921152), another TSWV isolate from Japan (AB198742) and isolate LGMTSG, a reassortant of Groundnut ringspot virus and Tomato chlorotic spot virus (HQ644142). Impatiens necrotic spot virus (INSV) isolate NL-07 from the Netherlands (X93218), INSV isolates Phalaenopsis (GQ336991) and HDL (GU112505) from China, and another INSV isolate from Italy (DQ425094) formed another cluster. To the best of our knowledge this is the first report of the occurrence of TSWV on tree tomato in Ecuador.