A complex tomato virome associated with leaf curl disease in Tamil Nadu is revealed, driven by mixed viral infections and recombination and emphasizes the need for continued virome surveillance and integrated disease management in tomato production systems.
Abstract
Background
Begomoviruses are circular single-stranded DNA viruses transmitted by the whitefly Bemisia tabaci and are major causal agents of leaf curl disease in tomato (Solanum lycopersicum L.). The present study aimed to comprehensively characterize the virome associated with symptomatic tomato plants collected from major agro-ecological regions of Tamil Nadu, India, using high-throughput sequencing (HTS).
Results
HTS based virome analysis of tomato plants exhibiting severe leaf curl symptoms revealed a complex viral community. The virosphere includes multiple begomoviruses, namely tomato leaf curl New Delhi virus (ToLCNDV), tomato leaf curl Bangalore virus (ToLCBaV), tomato leaf curl Karnataka virus, and chilli leaf curl virus (ChiLCV), along with associated alpha- and betasatellites. In addition, RNA viruses including pepper virus A (PepVA), chilli veinal mottle virus (ChiVMoV), and tomato chlorosis virus (ToCV) were also identified, indicating frequent occurrence of mixed infections. Full-length or coding-complete genome sequences were recovered for most viral components, whereas partial contigs were obtained for Southern tomato virus (STV) and tobacco vein distorting virus (TVDV). Notably, a novel recombinant monopartite begomovirus, tentatively named tomato leaf curl Dindigul virus (ToLCDiV), showed < 89.82% nucleotide identity with known begomovirus sequences. In addition, a distinct alphasatellite, tomato leaf curl Madurai alphasatellite (ToLCMdA) showed 86.74% nucleotide identity with known alphasatellites, supporting its distinctiveness based on ICTV species demarcation criteria. Recombination analysis suggested that ToLCDiV may have originated from parental lineages related to ToLCBaV and tomato leaf curl Gujarat virus (ToLCGV), with recombination breakpoints in the AC1, AC4, and intergenic regions.
Conclusion
This study revealed a complex tomato virome associated with leaf curl disease in Tamil Nadu, driven by mixed viral infections and recombination. The detection of the putative novel recombinant begomovirus ToLCDiV and distinct alphasatellite ToLCMdA highlights the emergence of new virus-satellite components and emphasizes the need for continued virome surveillance and integrated disease management in tomato production systems.
Quantitative PCR showed viral accumulation of 105–10⁹ copies/μL, confirming the synergistic role of DNA-B and betasatellites in severe symptom induction and systemic infection, underscoring the complexity of begomovirus pathogenesis.
K. Sivagnanapazham, G. Karthikeyan, N. Boopathi et al.· 3 Biotech· 0 citations
BpLCrV was, for the first time, identified and characterized as a novel begomovirus that infects not only weeds but also different important crops, potentially threatening agricultural production.
This is the first report of RoLCuV, a novel DNA-B, PaLCrV, and HYVA infecting D. erecta variegata in Pakistan, and the presence of rose leaf curl virus accompanied by a novel recombinant DNA-B, tentatively named "rose leaf curl virus DNA-B."
Background/Objective. High whitefly populations and incidence of up to 90% of tomato plants showing mosaic, intervenial chlorosis, deformation, rugosity and leaf necrosis, associated with virus and viroids, were observed at a high-tech greenhouse in Atlacomulco, State of Mexico. To identify the viruses or viroids associated with these symptoms, the withefly species, as well as to determine if the insects were carrying any of these pathogens, monthly sampling was conducted over a two-year period, collecting plant leaf tissue and adult whiteflies.
Materials y Methods. A total of 347 plants (211 symptomatic and 136 asymptomatic) were analyzed using immunostrips for impatiens necrotic spot virus (Orthotospovirus impatiensnecromaculae), tomato spotted wilt virus (O. tomatomaculae), tobacco mosaic virus (Tobamovirus tabaci), tomato mosaic virus (T. tomatotessellati), pepino mosaic virus (Potexvirus pepini) and cucumber mosaic virus (Cucumovirus CMV), as well as by RTPCR and PCR using universal primers for viroids and viruses of the genera Pospiviroid and Begomovirus, respectively. DNA was extracted from the insects and analyzed by PCR with specific primers that amplify a fragment of the mitocondrial gene (mtCOI) to identify the whitefly species, as well as universal primers for begomoviruses to determine if the insects were carriers of these viruses. Results. The results obtained using immunostrips were negative. The fragments amplified by RT-PCR and PCR were sequenced and corresponded to tomato planta macho viroid (Pospiviroid machoplantae) and tomato severe leaf curl virus (Begomovirus solanumseveri). Of the plants analyzed, 49.56% tested positive for the pospiviroid, 23.9% for the begomovirus, and 8.93% for both. Infection caused solely by the viroid was the only one that resulted in an asymptomatic condition. Bemisia tabaci was identified as the whitefly species and was determined to be a carrier of B. solanumseveri.
Conclusions. Symptoms of mosaic, intervenial chlorosis, leaf deformation and necrosis, blistering, and rugosity observed in tomato plants were associated with individual infection by tomato planta macho viroid (Pospiviroid machoplantae), and tomato severe leaf curl virus (Begomovirus solanumseveri), as well as co-infection by both. This is the first report of natural co-infection of tomato planta macho viroid and tomato leaf curl virus. The presence of asymptomatic plants is a key factor to consider when carrying out cultural practices to minimize mechanical transmission of the viroid.
María del Carmen Zúñiga-Romano, D. L. Ochoa-Martínez, R. I. Rojas-Martínez et al.· Revista Mexicana de Fitopato...· 0 citations