Tomato Yellow Leaf Curl Virus Research Articles

First report of tomato yellow leaf curl virus (TYLCV) infecting Solanum nigrum plants in Mauritius

First report of tomato yellow leaf curl virus (TYLCV) infecting Solanum nigrum plants in Mauritius

Serologic and molecular determination and phylogenetic analysis of some viruses infecting pepper in Turkey

Viruses are among the major agents causing yield loss in pepper production. During the 2016-2017, a survey was performed in pepperfields to determine of some viruses in pepper plants showing virus-like symptoms in different provinces of Turkey. Plant samples wereassayed using DAS-ELISA with specific antisera for cucumber mosaic virus (CMV), tomato spotted wilt virus (TSWV), tomato yellow leafcurl virus (TYLCV), alfalfa mosaic virus (AMV), and pepper mild mottle virus (PMMoV). The DAS-ELISA results indicated that 42.2, 17.5,17.5, and 10.6 of the 421 samples were infected with CMV, TSWV, AMV, and PMMoV, respectively. The positive samples were furtheranalysed by RT-PCR and sequencing. Based on sequence analyses, a phylogenetic tree was drawn for each of CMV, PMMoV and AMV.Phylogenetic analysis showed that CMV isolates were placed in subgroup IA within the major group I. The AMV isolates were classifiedwithin four clades and showed a high variability. PMMoV isolates were grouped with Serbia, Brazil, and Japan isolates within the group I.One AMW isolates determined possible recombinant isolates. Further studies needed for more information about recombinant isolatesand evolutions. The analyses of the molecular structure of viruses is important for the accurate diagnosis of the pathogen and to applythe right method of management strategies for controlling plant viruses in agriculture.

Le virus des feuilles jaunes en cuillère de la tomate favorise la tolérance au stress de la sécheresse de Solanum lycopersicum L.

Plants develop defence mechanisms in response to abiotic and biotic stresses that can have both negative and positive effects. Tomatoes grown in the field are normally exposed to abiotic stresses such as high temperatures and water shortages, as well as biotic stresses such as tomato yellow leaf curl virus (TYLCV), which greatly reduces productivity in this crop. In this study, two TYLCV Korean isolates were used as molecular and physiological tools to identify interactions between TYLCV infection and drought tolerance in tomato. The tomatoes were inoculated by TYLCV-infectious clones and exposed to drought stress, which led to wilted leaves on plants in the mock group, while those on TYLCV-inoculated plants showed no significant drought symptoms. Moreover, the average relative water content (RWC) was higher in TYLCV-infected plants than in the mock group, and genes associated to drought tolerance were pre-activated in well-watered tomato plants. These results confirm that TYLCV infection enhance drought tolerance in tomato plants and pre-inoculation with symptomless TYLCV isolates can be applied to tomato plants before being cultivated in water-deficit regions.

An Effective Integrated Machine Learning Framework for Identifying Severity of Tomato Yellow Leaf Curl Virus and Their Experimental Validation.

Tomato yellow leaf curl virus (TYLCV) dispersed across different countries, specifically to subtropical regions, associated with more severe symptoms. Since TYLCV was first isolated in 1931, it has been a menace to tomato industrial production worldwide over the past century. Three groups were newly isolated from TYLCV-resistant tomatoes in 2022; however, their functions are unknown. The development of machine learning (ML)-based models using characterized sequences and evaluating blind predictions is one of the major challenges in interdisciplinary research. The purpose of this study was to develop an integrated computational framework for the accurate identification of symptoms (mild or severe) based on TYLCV sequences (isolated in Korea). For the development of the framework, we first extracted 11 different feature encodings and hybrid features from the training data and then explored 8 different classifiers and developed their respective prediction models by using randomized 10-fold cross-validation. Subsequently, we carried out a systematic evaluation of these 96 developed models and selected the top 90 models, whose predicted class labels were combined and considered as reduced features. On the basis of these features, a multilayer perceptron was applied and developed the final prediction model (IML-TYLCVs). We conducted blind prediction on 3 groups using IML-TYLCVs, and the results indicated that 2 groups were severe and 1 group was mild. Furthermore, we confirmed the prediction with virus-challenging experiments of tomato plant phenotypes using infectious clones from 3 groups. Plant virologists and plant breeding professionals can access the user-friendly online IML-TYLCVs web server at https://balalab-skku.org/IML-TYLCVs, which can guide them in developing new protection strategies for newly emerging viruses.

The primase subunits of DNA polymerase α, PRIM1 and PRIM2, are required for the replication of the geminivirus tomato yellow leaf curl virus in the host plant.

Geminiviruses are causal agents of devastating diseases in crops. Geminiviral genomes are single-stranded (ss) circular DNA molecules that replicate in the nucleus of the infected cell through double-stranded (ds) intermediates by co-opting the plant DNA replication machinery. However, the identity of the plant DNA polymerases enabling geminiviral replication has remained largely elusive. Recently, we showed that DNA polymerase α mediates the ss-to-ds conversion of tomato yellow leaf curl virus (TYLCV), and is therefore essential for the infection. Here, we provide data indicating that the primase subunits of DNA polymerase α, PRIM1 and PRIM2, are also required for TYLCV replication.

High-Throughput Sequencing Identified Distinct Bipartite and Monopartite Begomovirus Variants Associated with DNA-Satellites from Tomato and Muskmelon Plants in Saudi Arabia.

The studies on the prevalence and genetic diversity of begomoviruses in Saudi Arabia are minimal. In this study, field-grown symptomatic tomato and muskmelon plants were collected, and initially, begomovirus infection was confirmed by the core coat protein sequences. Four tomato and two muskmelon plants with viral infections were further evaluated for Illumina MiSeq sequencing, and twelve sequences (2.7-2.8 kb) equivalent to the full-length DNA-A or DNA-B components of begomoviruses were obtained along with eight sequences (~1.3-1.4 kb) equivalent to the begomovirus-associated DNA-satellite components. Four begomovirus sequences obtained from tomato plants were variants of tomato yellow leaf curl virus (TYLCV) with nt sequence identities of 95.3-100%. Additionally, two tomato plants showed a mixed infection of TYLCV and cotton leaf curl Gezira virus (CLCuGeV), okra yellow crinkle Cameroon alphasatellite (OYCrCMA), and okra leaf curl Oman betasatellite (OLCuOMB). Meanwhile, from muskmelon plants, two sequences were closely related (99-99.6%) to the tomato leaf curl Palampur virus (ToLCPalV) DNA-A, whereas two other sequences showed 97.9-100% sequence identities to DNA-B of ToLCPalV, respectively. Complete genome sequences of CLCuGeV and associated DNA-satellites were also obtained from these muskmelon plants. The nt sequence identities of the CLCuGeV, OYCrCMA, and OLCuOMB isolates obtained were 98.3-100%, 99.5-100%, and 95.6-99.7% with their respective available variants. The recombination was only detected in TYLCV and OLCuOMB isolates. To our knowledge, this is the first identification of a mixed infection of bipartite and monopartite begomoviruses associated with DNA-satellites from tomato and muskmelon in Saudi Arabia. The begomovirus variants reported in this study were clustered with Iranian isolates of respective begomovirus components in the phylogenetic dendrogram. Thus, the Iranian agroecological route can be a possible introduction of these begomoviruses and/or their associated DNA-satellites into Saudi Arabia.

Natural resistance of tomato plants to Tomato yellow leaf curl virus.

Tomato yellow leaf curl virus (TYLCV) is one of the most harmful afflictions in the world that affects tomato growth and production. Six regular antagonistic genes (Ty-1, Ty-2, Ty-3, Ty-4, ty-5, and Ty-6) have been transferred from wild germplasms to commercial cultivars as TYLCV protections. With Ty-1 serving as an appropriate source of TYLCV resistance, only Ty-1, Ty-2, and Ty-3 displayed substantial levels of opposition in a few strains. It has been possible to clone three TYLCV opposition genes (Ty-1/Ty-3, Ty-2, and ty-5) that target three antiviral safety mechanisms. However, it significantly impacts obtaining permanent resistance to TYLCV, trying to maintain opposition whenever possible, and spreading opposition globally. Utilizing novel methods, such as using resistance genes and identifying new resistance resources, protects against TYLCV in tomato production. To facilitate the breeders make an informed decision and testing methods for TYLCV blockage, this study highlights the portrayal of typical obstruction genes, common opposition sources, and subatomic indicators. The main goal is to provide a fictitious starting point for the identification and application of resistance genes as well as the maturation of tomato varieties that are TYLCV-resistant.

Research Article A new Informatics Framework for Evaluating the Codon Usage Metrics, Evolutionary Models and Phylogeographic reconstruction of Tomato yellow leaf curl virus (TYLCV) in different regions of Asian countries

Tomato yellow leaf curl virus (TYLCV) is a major devastating viral disease, majorly affecting the tomato production globally. The disease is majorly transmitted by the Whitefly. The Begomovirus (TYLCV) having a six major protein coding genes, among them the C1/AC1 is evidently associated with viral replication. Owing to immense role of C1/AC1 gene, the present study is an initial effort to elucidate the factors shaping the codon usage bias and evolutionary pattern of TYLCV-C1/AC1 gene in five major Asian countries. Based on publically available nucleotide sequence data the Codon usage pattern, Evolutionary and Phylogeographic reconstruction was carried out. The study revealed the presence of significant variation between the codon bias indices in all the selected regions. Implying that the codon usage pattern indices (eNC, CAI, RCDI, GRAVY, Aromo) are seriously affected by selection and mutational pressure, taking a supremacy in shaping the codon usage bias of viral gene. Further, the tMRCA age was 1853, 1939, 1855, 1944, 1828 for China, India, Iran, Oman and South Korea, respectively for TYLCV-C1/AC1 gene. The integrated analysis of Codon usage bias, Evolutionary rate and Phylogeography analysis in viruses signifies the positive role of selection and mutational pressure among the selected regions for TYLCV (C1/AC1) gene.

The V2 Protein from the Geminivirus Tomato Yellow Leaf Curl Virus Largely Associates to the Endoplasmic Reticulum and Promotes the Accumulation of the Viral C4 Protein in a Silencing Suppression-Independent Manner.

Viruses are strict intracellular parasites that rely on the proteins encoded in their genomes for the effective manipulation of the infected cell that ultimately enables a successful infection. Viral proteins have to be produced during the cell invasion and takeover in sufficient amounts and in a timely manner. Silencing suppressor proteins evolved by plant viruses can boost the production of viral proteins; although, additional mechanisms for the regulation of viral protein production likely exist. The strongest silencing suppressor encoded by the geminivirus tomato yellow leaf curl virus (TYLCV) is V2: V2 suppresses both post-transcriptional and transcriptional gene silencing (PTGS and TGS), activities that are associated with its localization in punctate cytoplasmic structures and in the nucleus, respectively. However, V2 has been previously described to largely localize in the endoplasmic reticulum (ER), although the biological relevance of this distribution remains mysterious. Here, we confirm the association of V2 to the ER in Nicotiana benthamiana and assess the silencing suppression activity-independent impact of V2 on protein accumulation. Our results indicate that V2 has no obvious influence on the localization of ER-synthesized receptor-like kinases (RLKs) or ER quality control (ERQC)/ER-associated degradation (ERAD), but dramatically enhances the accumulation of the viral C4 protein, which is co-translationally myristoylated, possibly in proximity to the ER. By using the previously described V2C84S/86S mutant, in which the silencing suppression activity is abolished, we uncouple RNA silencing from the observed effect. Therefore, this work uncovers a novel function of V2, independent of its capacity to suppress silencing, in the promotion of the accumulation of another crucial viral protein.

Silencing of SlDRB1 gene reduces resistance to tomato yellow leaf curl virus (TYLCV) in tomato (Solanum lycopersicum)

ABSTRACT Double-stranded RNA-binding proteins are small molecules in the RNA interference (RNAi) pathway that form the RNAi machinery together with the Dicer-like protein (DCL) as a cofactor. This machinery cuts double-stranded RNA (dsRNA) to form multiple small interfering RNAs (siRNAs). Our goal was to clarify the function of DRB in tomato resistant to TYLCV. In this experiment, the expression of the SlDRB1 and SlDRB4 genes was analyzed in tomato leaves by qPCR, and the function of SlDRB1 and SlDRB4 in resistance to TYLCV was investigated by virus-induced gene silencing (VIGS). Then, peroxidase activity was determined. The results showed that the expression of SlDRB1 gradually increased after inoculation of ‘dwarf tomato’ plants with tomato yellow leaf curl virus (TYLCV), but this gene was suppressed after 28 days. Resistance to TYLCV was significantly weakened after silencing of the SlDRB1 gene. However, there were no significant expression differences in SlDRB4 after TYLCV inoculation. Our study showed that silencing SlDRB1 attenuated the ability of tomato plants to resist virus infection; therefore, SlDRB1 may play a key role in the defense against TYLCV in tomato plants, whereas SlDRB4 is likely not involved in this defense response. Taken together, These results suggest that the DRB gene is involved in the mechanism of antiviral activity.

First Report of the Satellite DNA Beta Associated with Tomato Yellow Leaf Curl Virus – Mild on Tomato in Iraq

In November 2021, severe symptoms of TYLCV disease were observed in tomato fields in Karbala Province, Iraq. Symptomatic tomato samples were observed on 20 to 30% of plants. Samples of symptomatic plants were collected randomly. TYLCV-specific PCR primers were employed to confirm the presence of the virus. Total DNA was extracted and used as templates for next-generation sequencing. The unmapped reads were subjected to de novo assembly. The contigs assembled were compared with GenBank data of plant viruses. A BLASTn analysis revealed 99.34% similarity with tomato yellow leaf curl virus-mild (MT583814.1). This finding was confirmed by a PCR test using specific primers. Additionally, there was 94.66% pairwise identity with cotton leaf curl Gezira betasatellite (CLCuGB) isolate Al-Ain (KM279620.1). The universal primer pair for detection of betasatellites was applied, followed by Sanger sequencing of the amplicons, which confirmed the infection of all the tested plants with CLCuGB. The DNA sequence of CLCuGB has accession number ON206651. To verify the presence of TYLCV-mild and betasatellite, a field survey was conducted in the main regions of tomato cultivation in Karbala Province, Iraq, in November 2021. Symptomatic leaf samples were collected randomly from 40 fields and analyzed for virus infections. This analysis revealed that the virus and its satellite are distributed throughout the province. To our knowledge, this is the first record of occurrence and complete genome sequence of CLCuGB, associated with TYLCV-mild, in tomato fields in Iraq.

Vector acquisition and co-inoculation of two plant viruses influences transmission, infection, and replication in new hosts

This study investigated the role of vector acquisition and transmission on the propagation of single and co-infections of tomato yellow leaf curl virus (TYLCV,) and tomato mottle virus (ToMoV) (Family: Geminiviridae, Genus: Begomovirus) by the whitefly vector Bemisia tabaci MEAM1 (Gennadius) in tomato. The aim of this research was to determine if the manner in which viruses are co-acquired and co-transmitted changes the probability of acquisition, transmission and new host infections. Whiteflies acquired virus by feeding on singly infected plants, co-infected plants, or by sequential feeding on singly infected plants. Viral titers were also quantified by qPCR in vector cohorts, in artificial diet, and plants after exposure to viruliferous vectors. Differences in transmission, infection status of plants, and titers of TYLCV and ToMoV were observed among treatments. All vector cohorts acquired both viruses, but co-acquisition/co-inoculation generally reduced transmission of both viruses as single and mixed infections. Co-inoculation of viruses by the vector also altered virus accumulation in plants regardless of whether one or both viruses were propagated in new hosts. These findings highlight the complex nature of vector-virus-plant interactions that influence the spread and replication of viruses as single and co-infections.

Refining the emergence scenario of the invasive recombinant Tomato yellow leaf curl virus -IS76

TYLCV-IS76, a unique recombinant between tomato yellow leaf curl virus (TYLCV) and tomato yellow leaf curl Sardinia virus (TYLCSV), has replaced its parental viruses in southern Morocco. To refine its emergence scenario, its fitness was monitored experimentally in conditions aiming at reproducing natural situations, i.e. superinfection of plants already infected with parental viruses and competition with other TYLCV/TYLCSV recombinants (LSRec) automatically generated in plants coinfected with TYLCV and TYLCSV. TYLCV-IS76 accumulated significantly more than parental viruses regardless of plant age and superinfection delay. Although TYLCV-IS76 and LSRec both accumulated more than parental viruses in laboratory conditions, LSRec were displaced by TYLCV-IS76 in nature like parental viruses were. TYLCV-IS76 did not exhibit any vector transmission advantage over LSRec and TYLCV the most competitive parental virus. Thus, it is apparently only in the plant compartment that the recombination event that generated TYLCV-IS76, induced the competitiveness advantage by which the last became first.

Antagonism of tomato spotted wilt virus against tomato yellow leaf curl virus in Nicotiana benthamiana detected by transcriptome analysis.

Tomato spot wilt virus (TSWV) and tomato yellow leaf curl virus (TYLCV) are highly harmful viruses in agricultural production, which can cause serious economic losses to crops and even devastating consequences for vegetable yield in some countries and regions. Although the two viruses belong to different families and have different transmission vectors, they share most hosts. This study aimed to examine the transcriptomic expression of single and mixed inoculations of TSWV and TYLCV, leading to antagonism using high-throughput RNA sequencing. We confirmed the single and mixed infections of these viruses in Nicotiana benthamiana (N. benthamiana) by artificial inoculation. And the expression changes of related genes and their biological functions and pathways during the mixed infection of TSWV and TYLCV were analyzed by comparative transcriptome. Basically, similar symptoms were observed in the plants singly infected with TSWV and co-infected with TYLCV; the symptoms of TYLCV in the co-infected plants were not obvious compared with single TYLCV infections. When inoculated with TYLCV, the accumulation of the virus significantly reduced in single and mixed infections with TSWV; the TSWV accumulated slightly less in co-infection with TYLCV, whereas this reduction was much smaller than that of TYLCV. The results suggested that TSWV had an antagonistic effect on the accumulation of TYLCV in N. benthamiana. It mainly focused on the changes in unique differentially expressed genes (DEGs) caused by the co-infection of TSWV and TYLCV. The eight pathways enriched by upregulated DEGs mainly included amino acid biosynthesis, citrate cycle (or tricarboxylic acid cycle, TCA cycle), and so on. However, only pentose phosphate pathway (PPP) and peptidoglycan biosynthesis could be downregulated in the Kyoto Encyclopedia of Genes and Genomes pathway in which peptidoglycan biosynthesis was involved in upregulated and downregulated pathways. The antagonistic effect of TSWV on TYLCV in N.benthamiana and the change trends and specific pathways of DEGs in this process were found. Our study provided new insights into the host regulation and competition between viruses in response to TSWV and TYLCV mixed infection.

ToLCNDV-ES infection in tomato is enhanced by TYLCV: Evidence from field survey and agroinoculation.

The tomato leaf curl New Delhi virus (ToLCNDV), a bipartite begomovirus (family Geminiviridae), poses a significant threat to various horticultural crops in many Asian and Mediterranean countries. Since its identification, the Asian strain of this virus has exhibited severe infectivity and caused high yield loss in tomato and cucurbit production in the Indian subcontinent and other parts of Asia. ToLCNDV-ES, a different strain of ToLCNDV, emerged recently in the Mediterranean Basin and caused significant outbreaks in Cucurbitaceae species but has shown low adaptation to tomatoes. In a field survey, tomato plants infected with this Mediterranean strain were not discovered. Nevertheless, the same field survey revealed that ToLCNDV-ES occurred in natural double infection with tomato yellow leaf curl virus (TYLCV) in tomato plants with an infection ratio of up to 50%. Moreover, results obtained from experiments where tomato plants agro-inoculated simultaneously with infectious clones of ToLCNDV-ES and TYLCV showed that ToLCNDV-ES was detected in tomatoes while synergized with TYLCV with infection ratios similar to those found under field conditions. Quantitative PCR data indicated the highest amount of ToLCNDV in co-infected plants and no significant change in TYLCV titers among the different mixed infections. Moreover, it was ascertained that not all begomoviruses can enhance the infectivity of Mediterranean ToLCNDV isolates in tomato plants. Our study reports a new finding regarding the ToLCNDV-ES response in tomato while synergized with TYLCV with evidence from both field and laboratory conditions.

Lisianthus enation leaf curl virus, a begomovirus new to Japan, is more virulent than the prevalent tomato yellow leaf curl virus in Ty-gene-mediated resistant tomato cultivars

Lisianthus enation leaf curl virus, a begomovirus new to Japan, is more virulent than the prevalent tomato yellow leaf curl virus in Ty-gene-mediated resistant tomato cultivars

Exploiting Virus Infection to Protect Plants from Abiotic Stresses: Tomato Protection by a Begomovirus.

Tomato cultivation is threatened by environmental stresses (e.g., heat, drought) and by viral infection (mainly viruses belonging to the tomato yellow leaf curl virus family-TYLCVs). Unlike many RNA viruses, TYLCV infection does not induce a hypersensitive response and cell death in tomato plants. To ensure a successful infection, TYLCV preserves a suitable cellular environment where it can reproduce. Infected plants experience a mild stress, undergo adaptation and become partially "ready" to exposure to other environmental stresses. Plant wilting and cessation of growth caused by heat and drought is suppressed by TYLCV infection, mainly by down-regulating the heat shock transcription factors, HSFA1, HSFA2, HSFB1 and consequently, the expression of HSF-regulated stress genes. In particular, TYLCV captures HSFA2 by inducing protein complexes and aggregates, thus attenuating an acute stress response, which otherwise causes plant death. Viral infection mitigates the increase in stress-induced metabolites, such as carbohydrates and amino acids, and leads to their reallocation from shoots to roots. Under high temperatures and water deficit, TYLCV induces plant cellular homeostasis, promoting host survival. Thus, this virus-plant interaction is beneficial for both partners.

Exogenous Nitric Oxide Alleviates the Damage Caused by Tomato Yellow Leaf Curl Virus in Tomato through Regulation of Peptidase Inhibitor Genes.

The tomato yellow leaf curl virus (TYLCV) is the causal agent of one of the most severe diseases affecting tomato growth; however, nitric oxide (NO) can mediate plant resistance. This study investigated the molecular mechanism of exogenous NO donor-mediated disease resistance in tomato seedlings. Tomato seedlings were treated with sodium nitroprusside and TYLCV and subjected to phenotypic, transcriptomic, and physiological analyses. The results show that exogenous NO significantly reduced disease index, MDA content, and virus content (71.4%), significantly increased stem length and fresh weight of diseased plants (p < 0.05), and improved photosynthesis with an induction effect of up to 44.0%. In this study, it was found that the reduction in virus content caused by the increased expression of peptidase inhibitor genes was the main reason for the increased resistance in tomatoes. The peptidase inhibitor inhibited protease activity and restrained virus synthesis, while the significant reduction in virus content inevitably caused a partial weakening or shutdown of the disease response process in the diseased plant. In addition, exogenous NO also induces superoxide dismutase, peroxidase activity, fatty acid elongation, resistance protein, lignin, and monoterpene synthesis to improve resistance. In summary, exogenous NO enhances resistance in tomatoes mainly by regulating peptidase inhibitor genes.

Combinatorial interactions between viral proteins expand the potential functional landscape of the tomato yellow leaf curl virus proteome.

Viruses manipulate the cells they infect in order to replicate and spread. Due to strict size restrictions, viral genomes have reduced genetic space; how the action of the limited number of viral proteins results in the cell reprogramming observed during the infection is a long-standing question. Here, we explore the hypothesis that combinatorial interactions may expand the functional landscape of the viral proteome. We show that the proteins encoded by a plant-infecting DNA virus, the geminivirus tomato yellow leaf curl virus (TYLCV), physically associate with one another in an intricate network, as detected by a number of protein-protein interaction techniques. Importantly, our results indicate that intra-viral protein-protein interactions can modify the subcellular localization of the proteins involved. Using one particular pairwise interaction, that between the virus-encoded C2 and CP proteins, as proof-of-concept, we demonstrate that the combination of viral proteins leads to novel transcriptional effects on the host cell. Taken together, our results underscore the importance of studying viral protein function in the context of the infection. We propose a model in which viral proteins might have evolved to extensively interact with other elements within the viral proteome, enlarging the potential functional landscape available to the pathogen.

The Streptomyces chromofuscus Strain RFS-23 Induces Systemic Resistance and Activates Plant Defense Responses against Tomato Yellow Leaf Curl Virus Infection

Insect-vectored plant viruses pose a serious threat to sustainable production of economically important crops worldwide. This demands a continuous search for environmentally-friendly, sustainable and efficient approaches based on biological agents to address the mounting challenges of viral disease management. To date, the efficacy of actinomycetes bacteria against DNA plant viruses remains unknown. Here, through comparative analyses, we demonstrate that the RFS-23 strain of Streptomyces cellulase possesses protective activity as it positively regulated the plant growth and development. and diminished the severity, of disease symptoms, together with reduced accumulation of Tomato yellow leaf curl virus (TYLCV) DNA. The RFS-23 strain maintained relative chlorophyll contents by promoting the expression of genes (CLH1, HEMA1 and PORA) associated with chlorophyll biogenesis. As compared to another strain, CTF-20, the RSF-23 induced a significantly higher expression of plant defense-related genes (NbCIS and NbNCED) associated with biogenesis and accumulation of salicylic acid and abscisic acid. Additionally, the activity of antioxidant enzymes (SOD, CAT, POD and MDA) was significantly enhanced by RSF-23 treatment, despite the presence of viral infection. These findings suggest that RSF-23 is a novel biocontrol agent with protective activity, and it could be a potential candidate for the management of plant viral infections.