A high viral diversity in tomato crops in Brazil is revealed by next generation sequencing analyses
Tomato is planted in Brazil mainly for fresh consumption and tomato paste production. Among the various pathogens that infect tomato plants in Brazil, viruses are particularly important due to their high incidence and the resulting losses caused. Diagnosis of viral diseases usually relies on detection methods directed to known viruses and close variants, either by serology or nucleic acid hybridization/ amplification. However, the advent of next generation sequencing (NGS) facilitated a deep analysis of viral populations, which can be used for identification, assembly and discovery of new viruses. Aiming to estimate the viral diversity present in tomato crops from three states of Brazil, five composite leaf samples were analyzed using NGS. The samples referred as Braz (collected in the Federal District, 2015); Ahol, Toca1, and Toca2 (São Paulo State, 2014), and RNY2 (Minas Gerais State, 2013) were submitted to semi-purification of viral particles and RNA extraction before RNA-seq (Illumina). The reads were filtered for quality, the contigs assembled (Velvet algorithm), and submitted to MegaBLAST analysis against a virus reference sequences database. These samples were collected from plants showing symptoms such as mosaic, chlorosis, leaf curling, chlorotic spots, necrosis and stunting. Known viruses belonging to nine genera, Crinivirus, Begomovirus, Tospovirus, Tobravirus, Potyvirus, Tobamovirus, Tymovirus, Potexvirus and Cucumovirus, were detected. Potentially undescribed and unreported viruses in tomatoes, such as an amalgavirus and an ilarvirus, were also detected and are under confirmation. The conclusion was that there is a high virus diversity present in tomato plants in Brazil, making tomato production a challenge to the growers. The crinivirus, Tomato chlorosis virus, was the most frequently found within the samplings, suggesting that it is widespread in the major tomato production areas. Two begomoviruses were detected, implying that this strategy is also useful to detect viruses with a DNA genome. Finally, this technique was particularly convenient to identify the viruses coexisting in tomatoes and to find unknown viruses that may threaten the tomato production in the country.
Martins, T.P., Rego, C.M., Nakasu, E.Y.T., Fernandes, F.R. and Inoue-Nagata, A.K. (2021). A high viral diversity in tomato crops in Brazil is revealed by next generation sequencing analyses. Acta Hortic. 1316, 99-106
Solanum lycopersicum, virus, NGS, virome, HTS