Tomato torrado virus is Transmitted by Bemisia tabaci and Infects Pepper and Eggplant in Addition to Tomato

Abstract

Torrao or torrado is an emerging disease that is causing serious economic losses in tomato crops of southeastern Spain. The causal agent has been shown to be a new picorna-like plant virus, tentatively named Tomato torrado virus (ToTV) (4). By using trap tomato plants in a greenhouse affected by torrado located in the Murcia Region of Spain, we obtained a ToTV isolate (ToTV-CE) that we have biologically and molecularly characterized. Subtracted cDNA libraries (1) and expressed sequence tags sequencing were used to determine the partial nucleotide sequence of ToTV-CE. We covered ≈53% of the virus genome (GenBank Accession Nos. EU476181 and EU476182) and found that ToTV-CE RNAs 1 and 2 had a high nucleotide similarity (98 and 99%, respectively) with the ToTV published sequences (2,4). ToTV-CE sequences also showed a 70% nt similarity with those of Tomato apex necrosis virus, a newly identified virus in tomato crops of the Culiacan area (Sinaloa, Mexico) (3). To characterize the host range of ToTV-CE, 6 to 10 plants belonging to 14 species were mechanically inoculated with extracts from ToTV-CE-infected Nicotiana benthamiana plants. The presence of ToTV in these plants was analyzed at 3 and 6 weeks postinoculation (PI) by molecular hybridization in dot-blots. The determined host range was in agreement with that described earlier (2,4), but additional hosts and nonhosts were identified. Thus, the virus did not infect melon (Cucumis melo var. cantaloupe), cucumber (C. sativus cv. Marketmore), squash (Cucurbita pepo cv. Negro Belleza), Chenopodium album ssp. Amaranticolor, or Chenopodium quinoa. The virus infected systemically N. benthamiana, N. glutinosa, N. rustica, tobacco (N. tabacum cvs. Xanthi nc and Samsun), Physalis floridana, pepper (Capsicum annuum cv. Italian Long Sweet), tomato (Solanum lycopersicum cv. Boludo), and eggplant (S. melongena cv. Black Beauty). Pepper plants displayed severe symptoms of infection consisting of marked mosaics and stunting (but no necrosis), but eggplant remained asymptomatic for up to 6 weeks PI. A simple assay was devised to analyze whether ToTV can be transmitted by whiteflies. ToTV-CE-infected tomato plants were placed together with three to eight healthy tomato seedlings inside insect-proof glass boxes. Adult Bemisia tabaci (100 to 800 individuals in three replicates) or Trialeurodes vaporariorum (100 individuals in one replicate) were released into each box. For both treatments, symptoms typically induced by ToTV appeared in one to seven tomato seedlings by 1 week after the release of the whiteflies. ToTV infection was confirmed by molecular hybridization in tissue prints of petiole cross sections at 10 days PI. These data are in agreement with those reported by Pospieszny et al. (2) and strongly suggest that both B. tabaci and T. vaporariorum can transmit ToTV. References: (1) L. Diachenko et al. Proc. Natl. Acad. Sci. USA 93:6025, 1996. (2) H. Pospieszny et al. Plant Dis. 91:1364, 2007 (3) M. Turina et al. Plant Dis. 91:932, 2007. (4) M. Verbeek et al. Arch. Virol. 152:881, 2007.

Epidemiología y variabilidad patogénica del virus del mosaico del pepino dulce (Pepino mosaic virus). Nuevas enfermedades asociadas a su presencia (torrao o cribado)

“…The obtained result of the higher sensibility of this molecular method compared to the ELISA is in accordance to those reported in previous assays for PepMV or other viruses (Sánchez-Navarro et al, 1998) vaporariorum (Wisler et al, 1998b;Pospieszny et al, 2007;Amari et al, 2008), and large populations of whiteflies often co-infect tomato fields worldwide. In addition since the first outbreak of ToCV in Spain, which affected tomato crops with an incidence of more than 30% of symptomatic plants in individual fields (Navas-Castillo et al, 2000), this virus has commonly infected tomato crops during different growing seasons (EPPO, 2005).…”

“…Remarkably, the three Nicotiana species had already been reported as virus hosts as well as D. inoxia (Verbeek et al, 2007a;Pospieszny et al, 2007;Amari et al, 2008). However, we report the susceptible response of D. stramonium to ToTV infection (33.3%) for the first time.…”

“…De este modo se expresa resistencia a ToTV cuando este gen está presente en la planta en homocigosis, mientras que las plantas heterocigóticas son susceptibles (Maris et al, 2007). Todas las especies recogidas en la Tabla 1.9 presentaron infección sistémica del virus, la mayoría de ellas con síntomas evidentes, a excepción de N. rustica que resultó asintomática en los estudios realizados (Verbeek et al, 2007a;Amari et al, 2008 Physalis floridana Rydb. Solanaceae Verbeek et al, 2007a;Amari et al, 2008;Pospieszny et al, 2009 S. lycopersicum L. Solanaceae Amari et al, 2008;Pospieszny et al, 2009 S. melongena L. Solanaceae Amari et al, 2008;Pospieszny et al, 2009 S. tuberosum L. Solanaceae Pospieszny et al, 2009 En cambio, especies de otras familias botánicas no resultaron infectadas con el virus tras su inoculación artificial (Tabla 1.10 (Budziszewska et al, 2008).…”

“…Las diferencias más notables encontradas entre el aislado tipo y el aislado polaco Wal03 es su longitud, debida a una inserción en el extremo 3´ y el tamaño de sus CP (Budziszewska et al, 2009). Las diferencias en el tamaño de las subunidades CP En el resto de aislados descritos de ToTV, únicamente se analizaron zonas concretas del genoma donde su identidad a nivel de nt con el aislado tipo fue siempre de más de un 98% Amari et al, 2008;Herrera-Vásquez et al, 2009a;Alfaro-Fernández et al, 2009a). En cambio, el ToMarV y el ToANV mostraron identidades en sus secuencias mucho menores con el ToTV, aunque entre ambos virus presentaron una relación más estrecha (Tabla 1.11), por lo que algunos autores plantearon que se tratasen como dos aislados o cepas del mismo virus como se ha indicado anteriormente (Verbeek et al, 2007b).…”

“…In a mid-transition area, both species co-exist all year long, especially during winter, and they even co-exist within a plant, exhibiting T. vaporariorum with a greater preference for younger leaves than B. tabaci (Arnó et al, 2006). Although both species have been reported to transmit ToTV Amari et al, 2008), the specificity and the parameters of the whitefly transmission remain unknown.…”