Characterization of Iranian Tomato aspermy virus isolates with a variant 2b gene sequence

Abstract

Three isolates of Tomato aspermy virus (TAV) were identified from two ornamental plants, Petunia hybrida and Chrysanthemum morifolium, sampled in Kerman province in the southeastern region of Iran. The complete genome of one isolate (Ker.Mah.P) and three open reading frames (ORFs), encoding coat protein (CP), movement protein (MP) and 2b protein of the three isolates were sequenced. The three genome segments of the Ker.Mah.P isolate (RNA-1, −2 and −3) are comprised of 3351, 3035 and 2194 nts, respectively. The nucleotide sequences of the three Iranian isolates were compared with other available sequences in GenBank, and the genome of Ker.Mah.P showed >96% sequence identity with sequences of TAV isolates. In a host range study, the three Iranian isolates induced chlorotic and necrotic symptoms on the true leaves of Cucumis sativus cv. Maximum F4 and systemic mottle and necrotic local lesions on Chenopodium amaranticolor, whereas other isolates whose sequences are deposited in GenBank cause only necrotic local lesions on these test plants. Sequences of the 2b gene of the three Iranian and one Chinese isolate have an additional 27 nt insert and it is possible that this domain, which adds nine amino acids to the 2b protein, may affect the biological properties of the virus. To the best of our knowledge, this is the first report of a TAV isolate from the Middle East whose genome has been sequenced, as well as the first global report of the natural occurrence of TAV in P. hybrida.