Phylogenetic analysis of coat protein gene of tomato mosaic virus isolates circulating in Ukraine

Abstract

Tomato mosaic virus (ToMV) induces highly infectious disease of vegetables, whereas use of virus-contaminated seed may lead to complete yield loss. This work was aimed at studying phylogenetic relationships of Ukrainian tomato isolates of ToMV with its known isolates by comparing nucleotide sequence of coat protein gene. ELISA, TEM, RT-PCR, sequence analysis using MEGA 5 software, and statistical methods. cDNAs of two novel Ukrainian isolates ToMV-ukr-5 and ToMV-ukr-10 corresponding to coat protein (CP) gene were sequenced and compared with other published ToMV sequences. On the constructed phylogenetic tree, ToMV isolates were grouped into two separate clusters. In addition to novel Ukrainian isolates ToMV-ukr-5 and ToMV-ukr-10, the first and larger cluster contained nearly all virus isolates used in this study with high (96-98,9 %) level of homology to Ukrainian isolates. The larger cluster was clearly separated into two subclusters: one grouping isolates with over 96,7 % identity with Ukranian isolates, and the other containing three strains and isolates with 96,1 % identity (tomato isolate SL-1, strain camellia isolated from a decorative plant, and isolate Dahlemense DSMZ PV-0135).Two novel Ukrainian isolates ToMV-ukr-5 and ToMV-ukr-10 have been isolated from tomato plants cultivated in open field conditions in different regions of Ukraine. Phylogenetic analysis confirmed high identity of Ukrainian isolates between themselves and with other published ToMV sequences. Ukrainian isolates were most homologous (>98 %) to Brazilian isolate Hemerocallis, to Chinese isolate G2, and to the following tomato isolates: AH4, Queensland, ToMV-tom and Ls-K, S14, and FERA_160205. The high level of homology was traced independently of the source of virus isolation, its plant host and their geography.