First Report of Tomato chlorosis virus Infecting Tomato in Sudan

Abstract

In March 2011, interveinal yellowing and necrosis symptoms on middle and lower leaves were observed in tomato (Solanum lycopersicum L., cv. Castle Rock) plants grown in three adjacent greenhouses of the Agricultural Research Corporation at Wad Medani (Gezira State, Sudan). These symptoms resembled those caused by Tomato chlorosis virus (ToCV) and Tomato infectious chlorosis virus (TICV) (4) (genus Crinivirus, family Closteroviridae). Whitefly (Bemisia tabaci) infestation was also observed in these greenhouses. Total RNA was extracted by TRIzol Reagent (Invitrogen, Carlsbad, CA) from symptomatic leaves and analyzed by dot-blot hybridization with digoxigenin-labelled RNA probes to the coat protein (CP) gene of ToCV and to the minor coat protein (CPm) gene of TICV. Positive signal was obtained only with the ToCV probe. Reverse transcription (RT)-PCR reactions were performed with two pairs of primers specific for the detection of ToCV, MA380(+) (5′-GTGAGACCCCGATGACAGAT-3′) and MA381(-) (5′-TACAGTTCCTTGCCCTCGTT-3′), specific to the CP gene (ToCV RNA 2) (3), and MA396(+) (5′-TGGTCGAACAGTTTGAGAGC-3′) and MA397(-) (5′-TGAACTCGAATTGGGACAGA-3′), specific to the RNA-dependent RNA polymerase (RdRp) gene (ToCV RNA 1) (1). DNA fragments of the expected sizes (436 and 763 bp, respectively) were obtained, thus supporting the presence of ToCV in the symptomatic samples. Amplified DNA fragments were cloned in pGEM-T Easy vector (Promega, Madison, WI) and one clone per amplicon was sequenced (Macrogen Inc., Seoul, South Korea). The highest nucleotide sequence identity of the CP gene fragment obtained (GenBank Accession No. JN411685) was 99.2% related with North American ToCV isolates from Florida (DQ234674), Colorado (DQ234675), and Georgia (HQ879842), while the RdRp gene fragment (JN411686) was more closely related (99.0%) to the Spanish AT80/99 isolate (DQ983480). Although yellowing symptoms similar to those reported here have been observed sporadically during the last few years in open-field tomato crops in the state of Gezira, additional studies are needed to determine the prevalence and economic impact of ToCV infections in tomato cultivation in Sudan. To our knowledge, ToCV has been found in continental Africa only in Morocco and South Africa, in the Mediterranean climate areas in the northern and southern edges of the continent, respectively (2). The finding of ToCV infecting tomato in Sudan raises the question of whether this virus is emerging also in other tropical areas of the continent and illustrates the need to monitor whitefly-infested areas within Africa for the presence of ToCV. References: (1) G. Lozano et al. J. Virol. 83:12973, 2009. (2) J. Navas-Castillo et al. Annu. Rev. Phytopathol. 49:219, 2011. (3) H. P. Trenado et al. Eur. J. Plant Pathol. 118:193, 2007. (4) G. C. Wisler et al. Plant Dis. 82:270, 1998.

Molecular characterization reveals Brazilian Tomato chlorosis virus to be closely related to a Greek isolate

“…ToCV was first described in tomato plants cultivated in Florida, USA, in 1989, and the disease was named "yellow leaf disorder" (Wisler et al, 1998). Since then, ToCV has been reported in many countries from the Americas, Europe, Africa and Asia (Fiallo-Olivé et al, 2011;Navas-Castillo et al, 2011). In Brazil, the presence of ToCV has been confirmed at least in five states (Barbosa et al, 2011), which are important tomato growing areas.…”

Performance of Bemisia tabaci MEAM1 and Trialeurodes vaporariorum on Tomato chlorosis virus (ToCV) infected plants

“…Tomato chlorosis virus (ToCV) (genus Crinivirus , family Closteroviridae ) is an economically important virus worldwide (Orfanidou, Dimitriou, Papayiannis, Maliogka, & Katis, ) transmitted semi‐persistently and was identified for the first time in tomato in 1996 (Wisler, Li, Liu, Lowry, & Duffus, ). Over the past two decades, Tomato chlorosis virus (ToCV) has spread to North America, South America, Europe, Africa, the Middle East and Asia (Accotto et al., ; Arruabarrena et al., ; Fiallo‐Olivé, Hamed, Moriones, & Navas‐Castillo, ; Hirota et al., ; Segev, Wintermantel, Polston, & Lapidot, ; Wisler et al., ). This virus can cause great damage, reducing tomato yields by 100% (Lozano, Moriones, & Navas‐Castillo, ; Velasco, Simón, Janssen, & Cenis, ).…”

P22 of tomato chlorosis virus, an RNA silencing suppressor, is naturally expressed in the infected plant

“…Since its first discovery nearly two decades ago (1), tomato chlorosis virus (ToCV) (the genus Crinivirus of the family Closteroviridae) has emerged as a serious disease problem in field and greenhouse tomato production worldwide (2)(3)(4)(5)(6)(7)(8)(9). The infected tomato plants exhibit symptoms including interveinal chlorosis, leaf brittleness, and limited necrotic flecking or leaf bronzing (10).…”