Tomato Yellow Leaf Curl Research Articles

Plant Leaf Diseases Classification Using Improved K-Means Clustering and SVM Algorithm for Segmentation

Several pests feed on leaves, stems, bases, and the entire plant, causing plant illnesses. As a result, it is vital to identify and eliminate the disease before causing any damage to plants. Manually detecting plant disease and treating it is pretty challenging in this period. Image processing is employed to detect plant disease since it requires much effort and an extended processing period. The main goal of this study is to discover the disease that affects the plants by creating an image processing system that can recognize and classify four different forms of plant diseases, including <i>Phytophthora infestans</i>, Fusarium graminearum, Puccinia graminis, tomato yellow leaf curl. Therefore, this work uses the Support vector machine (SVM) classifier to detect and classify the plant disease using various steps like image acquisition, Pre-processing, Segmentation, feature extraction, and classification. The gray level co-occurrence matrix (GLCM) and the local binary pattern features (LBP) are used to identify the disease-affected portion of the plant leaf. According to experimental data, the proposed technology can correctly detect and diagnose plant sickness with a 97.2 percent accuracy.

Disease Pandemics and Major Epidemics Arising from New Encounters between Indigenous Viruses and Introduced Crops.

Virus disease pandemics and epidemics that occur in the world’s staple food crops pose a major threat to global food security, especially in developing countries with tropical or subtropical climates. Moreover, this threat is escalating rapidly due to increasing difficulties in controlling virus diseases as climate change accelerates and the need to feed the burgeoning global population escalates. One of the main causes of these pandemics and epidemics is the introduction to a new continent of food crops domesticated elsewhere, and their subsequent invasion by damaging virus diseases they never encountered before. This review focusses on providing historical and up-to-date information about pandemics and major epidemics initiated by spillover of indigenous viruses from infected alternative hosts into introduced crops. This spillover requires new encounters at the managed and natural vegetation interface. The principal virus disease pandemic examples described are two (cassava mosaic, cassava brown streak) that threaten food security in sub-Saharan Africa (SSA), and one (tomato yellow leaf curl) doing so globally. A further example describes a virus disease pandemic threatening a major plantation crop producing a vital food export for West Africa (cacao swollen shoot). Also described are two examples of major virus disease epidemics that threaten SSA’s food security (rice yellow mottle, groundnut rosette). In addition, brief accounts are provided of two major maize virus disease epidemics (maize streak in SSA, maize rough dwarf in Mediterranean and Middle Eastern regions), a major rice disease epidemic (rice hoja blanca in the Americas), and damaging tomato tospovirus and begomovirus disease epidemics of tomato that impair food security in different world regions. For each pandemic or major epidemic, the factors involved in driving its initial emergence, and its subsequent increase in importance and geographical distribution, are explained. Finally, clarification is provided over what needs to be done globally to achieve effective management of severe virus disease pandemics and epidemics initiated by spillover events.

Laboratory and UAV-Based Identification and Classification of Tomato Yellow Leaf Curl, Bacterial Spot, and Target Spot Diseases in Tomato Utilizing Hyperspectral Imaging and Machine Learning

Tomato crops are susceptible to multiple diseases, several of which may be present during the same season. Therefore, rapid disease identification could enhance crop management consequently increasing the yield. In this study, nondestructive methods were developed to detect diseases that affect tomato crops, such as bacterial spot (BS), target spot (TS), and tomato yellow leaf curl (TYLC) for two varieties of tomato (susceptible and tolerant to TYLC only) by using hyperspectral sensing in two conditions: a) laboratory (benchtop scanning), and b) in field using an unmanned aerial vehicle (UAV-based). The stepwise discriminant analysis (STDA) and the radial basis function were applied to classify the infected plants and distinguish them from noninfected or healthy (H) plants. Multiple vegetation indices (VIs) and the M statistic method were utilized to distinguish and classify the diseased plants. In general, the classification results between healthy and diseased plants were highly accurate for all diseases; for instance, when comparing H vs. BS, TS, and TYLC in the asymptomatic stage and laboratory conditions, the classification rates were 94%, 95%, and 100%, respectively. Similarly, in the symptomatic stage, the classification rates between healthy and infected plants were 98% for BS, and 99–100% for TS and TYLC diseases. The classification results in the field conditions also showed high values of 98%, 96%, and 100%, for BS, TS, and TYLC, respectively. The VIs that could best identify these diseases were the renormalized difference vegetation index (RDVI), and the modified triangular vegetation index 1 (MTVI 1) in both laboratory and field. The results were promising and suggest the possibility to identify these diseases using remote sensing.

Tomato leaf curl Kunene virus: a novel tomato-infecting monopartite begomovirus from Namibia.

This is the first description of the complete genome sequence of a new monopartite begomovirus isolated from tomato with symptoms of tomato (yellow) leaf curl disease collected in northwestern Namibia, which we provisionally name "tomato leaf curl Kunene virus". The DNA-A-like nucleotide sequence shares the highest nucleotide sequence identity (82.8%) with tobacco leaf curl Zimbabwe virus (ToLCZWV). Phylogenetic analysis confirmed its affiliation with Old World monopartite begomoviruses. The discovery of a new begomovirus in a vegetable plant in Namibia highlights the importance of maintaining epidemiological surveillance in southern Africa.

Recent Emergence of the Mild Strain of Tomato yellow leaf curl virus as a Cause of Tomato Yellow Leaf Curl Disease of Processing Tomatoes (Solanum lycopersicon) in the Dominican Republic

In the early 1990s, the monopartite begomovirus Tomato yellow leaf curl virus (TYLCV) was introduced into the Dominican Republic (DO), and molecular characterization revealed it was an isolate of TYLCV-Israel (TYLCV-IL[DO]) (3,5). In 2006, a study of the variability of TYLCV in DO revealed that TYLCV-IL[DO] was associated with all samples of tomato yellow leaf curl (TYLC) tested and, thus, that the virus had been genetically stable for >15 years (2). However, in 2010 and 2011, 2 of 10 and 11 of 18 samples of TYLC, respectively, were negative for TYLCV infection based upon PCR with the TYLCV-specific primer pair, 2560v (5'-GAGAACAATTGGGATATG-3')/1480c (5'-AATCATGGATTCACGCAC-3'), which directs the amplification of a ~1.7 kb fragment. In 2011, two such samples from the Azua Valley were tested by PCR with the 1470v (5'-AGTGATGAGTTCCCCTGTGC-3')/UPC2 primer pair (1), and sequence analysis of the ~0.4 kb fragment amplified from both samples revealed infection with the mild strain of TYLCV (TYLCV-Mld). A primer specific for TYLCV-Mld was designed (2070v, 5'-AAACGGAGAAATATATAAGGAGCC-3'), and PCR with the 2070v/1480c primer pair directed the amplification of the expected ~2.1 kb fragment from all 11 TYLC samples collected in 2011 that were PCR-negative for TYLCV-IL[DO] infection. Sequence analyses confirmed these were TYLCV-Mld fragments. The complete TYLCV-Mld genome was amplified from two samples from the Azua Valley with Templiphi, the amplified DNA products digested with Sal I, and the resulting ~2.8 kb fragments ligated into Sal I-digested pGEM-11. The complete sequences of these isolates were 2,791 nt and 99% identical to each other and 98% identical to sequences of TYLCV-Mld isolates. The TYLCV-Mld isolates from the DO were designated TYLCV-Mld:DO:TY5:01:2011 (KJ913682) and TYLCV-Mld:DO:TY5:02:2011 (KJ913683). A multimeric clone of TYLCV-Mld:DO:TY5:01:2011 was generated in the binary vector pCAMBIA1300 by cloning a 2.2 kb Sal I-EcoRI fragment containing the intergenic region to generate a 0.8-mer (pCTYMld0.8), and then the full-length Sal I fragment was cloned into the Sal I site of pCTYMld0.8 to generate a 1.8-mer (pCTYMldDO-01-1.8). Tomato plants agroinoculated with Agrobacterium tumefaciens carrying pCTYMldDO-01-1.8 developed severe TYLC disease symptoms 10 to 14 days after inoculation, whereas plants inoculated with a strain carrying the empty vector did not develop symptoms. Samples of processing tomatoes with TYLC were collected in 2012 to 2014 in the DO and tested for TYLCV-IL[DO] and TYLCV-Mld by PCR with the 2560v/1480c and 2070v/1480c primers pairs, respectively; these samples had infections of 93% (13/14), 86% (18/21), and 61% (11/18) with TYLCV-Mld; 29% (4/14), 19% (4/21), and 56% (10/18) with TYLCV-IL[DO]; and 21% (3/14), 5% (1/21), and 28% (5/18) with both viruses, respectively. These results reveal that there has been a striking population shift in the begomovirus causing TYLC in the DO, with TYLCV-Mld becoming predominant. This may reflect selection pressure(s) favoring a small pre-existing population of TYLCV-Mld, such as new tomato varieties, or a recent introduction event, such as that described in Venezuela (4).

Characterization and distribution of tomato yellow margin leaf curl virus, a begomovirus from Venezuela

A begomovirus causing mottling and leaf deformation in tomato from the State of Mérida was cloned and sequenced. The virus has a bipartite genome comprised of a DNA-A (2,572 nucleotides) and a DNA-B (2,543 nucleotides) with a genome organization typical of New World begomoviruses. Both components share a common region of 115 nucleotides with 98% sequence identity. Phylogenetic analysis indicated that while no virus sequences were closely related, the A component was distantly related to those of two other tomato-infecting viruses, tomato leaf deformation virus and Merremia mosaic virus; and the DNA-B, to those of pepper huasteco yellow vein virus and Rhynchosia golden mosaic Yucatan virus. The DNA-A and DNA-B sequences were submitted to GenBank (accession no. AY508993 and AY508994, respectively) and later accepted by the International Committee on Taxonomy of Viruses as the genome of a member of a unique virus species with the name Tomato yellow margin leaf curl virus (TYMLCV). Tomato (Solanum lycopersicum L. 'Fl. Lanai') plants inoculated with cloned TYMLCV DNA-A and DNA-B became systemically infected and showed chlorotic margins and leaf curling. The distribution of TYMLCV in tomato-producing states in Venezuela was determined by nucleic acid spot hybridization analysis of 334 tomato leaf samples collected from ten states using a TYMLCV-specific probe and confirmed by PCR and sequencing of the PCR fragment. TYMLCV was detected in samples from the states of Aragua, Guárico, and Mérida, suggesting that TYMLCV is widely distributed in Venezuela.

Normes OEPP/EPPO Standards Diagnostics Diagnostic

Normes OEPP/EPPO Standards Diagnostics Diagnostic

Normes OEPP/EPPO Standards Diagnostics Diagnostic

Normes OEPP/EPPO Standards Diagnostics Diagnostic

Complete sequences of tomato leaf curl Palampur virus isolates infecting cucurbits in Iran

Tomato leaf curl disease (TLCD) and and tomato yellow leaf curl (TYLCD) is caused by a number of begomovirus species that collectively threaten tomato production worldwide. We report here that an ongoing TLCD and TYLCD epidemic in Iran is caused by variants of tomato leaf curl Palampur virus (ToLCPMV), a newly proposed begomovirus species previously only detected in India. Besides infecting tomatoes, we identified ToLCPMV as the causal agent of a cucurbit disease that has devastated greenhouse cucumber and melon farms in Jiroft, southeastern Iran. We found no convincing evidence that the ToLCPMV DNA-B sequences have been derived through inter-species recombination, however, all of the currently sampled ToLCPMV DNA-A sequences are descendents of a sequence that probably arose through recombination between a ToLCNDV isolate and a currently unsampled geminivirus species that falls outside the ToLCNDV-ToLCPMV cluster. The increasing incidence of ToLCPMV in different cultivated species throughout Iran may signal the emergence of a serious new threat to agricultural production throughout the Middle East.

Normes OEPP EPPO Standards Diagnostics Diagnostic

Normes OEPP EPPO Standards Diagnostics Diagnostic

Evidence of local evolution of tomato-infecting begomovirus species in West Africa: characterization of tomato leaf curl Mali virus and tomato yellow leaf crumple virus from Mali

Tomato yellow leaf curl (TYLC) and tomato leaf curl (ToLC) diseases are serious constraints to tomato production in Mali and other countries in West Africa. In 2003 and 2004, samples of tomato showing virus-like symptoms were collected during a survey of tomato virus diseases in Mali. Three predominant symptom phenotypes were observed: (1) TYLC/ToLC (stunted upright growth and upcurled leaves with interveinal yellowing and vein purpling), (2) yellow leaf crumple and (3) broccoli or bonsai (severe stunting and distorted growth). Squash blot (SB) hybridization with a general begomovirus probe and/or SB/PCR analyses revealed begomovirus infection in plants with each of these symptom phenotypes and no evidence of phytoplasma infection. Sequence analysis of PCR-amplified begomovirus fragments revealed two putative new begomovirus species associated with the TYLC/ToLC and yellow leaf crumple symptom phenotypes, respectively. Full-length clones of these begomoviruses were obtained using PCR and overlapping primers. When introduced into N. benthamiana and tomato plants, these clones induced upward leaf curling and crumpling (the TYLC/ToLC-associated begomovirus) or downward leaf curl/yellow mottle (yellow leaf crumple-associated begomovirus) symptoms. Thus, these begomoviruses were named tomato leaf curl Mali virus (ToLCMLV) and tomato yellow leaf crumple virus (ToYLCrV). The genome organization of both viruses was similar to those of other monopartite begomoviruses. ToLCMLV and ToYLCrV were most closely related to each other and to tobacco leaf curl Zimbabwe virus (TbLCZV-[ZW]) and tomato curly stunt virus from South Africa (ToCSV-ZA). Thus, these likely represent tomato-infecting begomoviruses that evolved from indigenous begomoviruses on the African continent. Mixed infections of ToLCMLV and ToYLCrV in N. benthamiana and tomato plants resulted in more severe symptoms than in plants infected with either virus alone, suggesting a synergistic interaction. Agroinoculation experiments indicated that both viruses induced symptomatic infections in tomato and tobacco, whereas neither virus induced disease symptoms in pepper, common bean, small sugar pumpkin, African eggplant, or Arabidopsis. Virus-specific PCR primers were developed for detection of ToLCMLV and ToYLCrV and will be used to further investigate the distribution and host range of these viruses.

Insect-screened cultivation to reduce the invasion of tomato crops by Bemisia tabaci: modelling the impact on virus disease and vector

1: In two experiments carried out in Guadeloupe, barriers were used to reduce the entry of the virus vector Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) to tomato plots. The barriers erected around the crop were of insect-proof cloth fences (<50 mesh), 1.5 m in height, in the first experiment with a deltamethrin-treated, insect-attracting strip facing inwards, and, in the second, with the barrier but no insecticide-treated strip. 2: A mathematical model of epidemic development was fitted to the symptom data from the treated and control (unprotected) tomato plots. There were two viruses present, tomato yellow leaf curl and potato yellow mosaic; specific detection confirmed that symptoms gave an accurate indication of infection and that the two virus diseases had similar progress curves. 3: Parameter estimates obtained by model-fitting suggested that the barriers reduced vector immigration by approximately 12-fold but that B. tabaci retention within the plots was also increased slightly despite the mortality caused by the insecticide-treated strips. Disease establishment was delayed by approximately 2 weeks. The results obtained in the second experiment involving barriers deployed without insecticide-treated strips could be explained by a large increase in B. tabaci retention within the barriers resulting in more rapid virus disease progress than in controls. The results of mathematical modelling indicate that partial insect barriers can be worse than none because sufficient whiteflies can enter to establish a population and, at the same time, large numbers are retained in the barrier plot, with the net effect being a more rapid population increase than in the absence of barriers.

Normes OEPP . EPPO Standards

Normes OEPP . EPPO Standards

Pepper (Capsicum annuum) Is a Dead-End Host for Tomato yellow leaf curl virus

ABSTRACT Tomato yellow leaf curl (TYLC) is one of the most devastating pathogens affecting tomato (Lycopersicon esculentum) worldwide. The disease is caused by a complex of begomovirus species, two of which, Tomato yellow leaf curl Sardinia virus (TYLCSV) and Tomato yellow leaf curl virus (TYLCV), are responsible for epidemics in Southern Spain. TYLCV also has been reported to cause severe damage to common bean (Phaseolus vulgaris) crops. Pepper (Capsicum annuum) plants collected from commercial crops were found to be infected by isolates of two TYLCV strains: TYLCV-Mld[ES01/99], an isolate of the mild strain similar to other TYLCVs isolated from tomato crops in Spain, and TYLCV-[Alm], an isolate of the more virulent TYLCV type strain, not previously reported in the Iberian Peninsula. In this work, pepper, Nicotiana benthamiana, common bean, and tomato were tested for susceptibility to TYLCV-Mld[ES01/99]and TYLCV-[Alm] by Agrobacterium tumefaciens infiltration, biolistic bombardment, or Bemisia tabaci inoculation. Results indicate that both strains are able to infect plants of these species, including pepper. This is the first time that infection of pepper plants with TYLCV clones has been shown. Implications of pepper infection for the epidemiology of TYLCV are discussed.

Busca por Tomato yellow leaf curl virus e Tomato yellow leaf curl Sardinia virus em tomateiros

A doença causada pelo complexo de vírus do tomato yellow leaf curl (TYLC) é muito séria em tomateiro, principalmente na América Central e Europa, e é causada por um complexo de begomovírus monopartidos. A doença torna-se predominante, mesmo em áreas com a presença de outros begomovírus. No Brasil, os problemas advindos da infecção por begomovírus uram entre os principais fatores de perdas e oneração de custos. A introdução do complexo TYLC representa uma grande ameaça para os produtores. Este estudo visou a realização de testes de detecção baseados em reação de polimerase em cadeia (PCR) e hibridização específicos em amostras suspeitas coletadas no estado de São Paulo. Um total de 46 amostras com sintomas lembrando aqueles causados pelo complexo TYLC foram coletados no município de Campinas. Todas as amostras foram negativas para detecção de Tomato yellow leaf curl virus e Tomato yellow leaf curl Sardinia virus, as duas espécies mais importantes do completo TYLC. Este resultado sugeriu que as duas espécies de vírus ainda não foram introduzidas no Brasil ou que ainda não apresentam uma larga distribuição.

Squash as a trap crop to protect tomato from whitefly-vectored tomato yellow leaf curl

The silverleaf whitefly, Bemisia argentifolii Bellows & Perring [also known as biotype B of the sweetpotato whitefly, B. tabaci (Gennadius)], is a key pest of tomato in southern Florida. Most damage by the whitefly is inflicted indirectly through the transmission of plant viruses, the most damaging of which is Tomato yellow leaf curl virus (TYLCV). Trap crops may be one means of reducing whitefly populations and TYLCV incidence in tomato. Because squash is more attractive to whitefly adults than tomato, it was evaluated as a trap crop in three field experiments conducted during the spring and fall of 2000 and the spring of 2001. Four, 15.25 m long rows of tomato were surrounded by 1.5 m of either squash or tomato and were transplanted about 3 weeks after the squash was seeded. The numbers of whitefly adults and nymphs and the incidence of plants with symptoms of tomato yellow leaf curl (TYLC) were determined weekly. The squash was harvested weekly to promote flowering, and fungicides were applied weekly for preventive control of fungal pathogens. In all experiments, a greater cumulative proportion of plants with symptoms of TYLC were observed on tomato plants surrounded by tomato, compared to tomato plants surrounded by squash. In general greater cumulative numbers of whitefly adults and nymphs were observed on tomato plants surrounded by tomato than on tomato plants surrounded by squash. Therefore, growing squash as a trap crop could be a useful cultural manipulation in managing the silverleaf whitefly and TYLC on tomato, although the management tactic may be more applicable to small-scale farm operations.

A new approach to evaluate relative resistance and tolerance of tomato cultivars to begomoviruses causing the tomato yellow leaf curl disease in Spain

A simple procedure to evaluate relative resistance and tolerance of tomato cultivars to the begomoviruses causing tomato yellow leaf curl (TYLC) disease in Spain was developed. To estimate the resistance and tolerance levels of a cultivar, several formulae were developed based on the ratio of infected plants, virus titre (estimated by tissue–print hybridization) and symptom intensity. The formulae were applied to five commercial tomato cultivars (Amoretto, Birloque, Royesta, Tovigreen and Ulises) naturally infected by TYLC viruses. The analyses showed that Ulises, Birloque and Tovigreen exhibited a moderate resistance, and Ulises was also highly tolerant. There was a positive correlation between symptom intensity and virus titre in infected plants, suggesting that the hybridization technique could also be used as an early estimator of tolerance. Finally, molecular hybridization and nucleotide sequence analyses of the begomovirus intergenic region showed that the local TYLC virus population consisted of a single species, Tomato yellow leaf curl virus (TYLCV, formerly TYLCV‐Israel), with low genetic variation (nucleotide identity between isolates higher than 97%).

Diversity of European begomoviruses: identification of a new disease complex*

The diversity of whitefly-transmitted begomoviruses in Europe is low, most being exotic, introduced species. The only agriculturally important viruses are two species causing tomato yellow leaf curl. These viruses are believed to have originated in the Middle East but have since spread right across the Mediterranean region. Two ornamentals (Abutilon and Lonicera japonica) were introduced into Europe from the New World and the Far East, respectively, for the striking symptoms induced by the viruses which infect them. The virus infecting honeysuckle (Honeysuckle yellow vein mosaic virus) has been shown to be part of newly identified cluster of begomoviruses which require an additional component, a satellite molecule termed DNA β, to induce symptoms in their host plants. A further begomovirus, Ipomoea yellow vein virus, which infects the weed Ipomoea indica, is present in the Mediterranean region. The precise origin and relationship of this virus to other begomoviruses is unclear.

Molecular Characterization of Begomoviruses Associated with Leafcurl Diseases of Tomato in Bangladesh, Laos, Malaysia, Myanmar, and Vietnam.

Production of tomato (Lycopersicon esculentum) in Bangladesh, Malaysia, Myanmar, Vietnam, and Laos has been severely affected by yellow leaf curl disease. Tomato leaf samples were collected from symptomatic tomato plants from farmers' fields in the five countries from 1997 to 1999. DNA was extracted from all samples, four from Vietnam, two each from Malaysia, Laos, and Myanmar, and seven from Bangladesh. Virus DNA was amplified by polymerase chain reaction (PCR) using the begomovirus-specific degenerate primer pair PAL1v 1978/PAR1c 715(1), which amplifies the top part of DNA A. All samples gave the expected 1.4-kb PCR product. The PCR product of one sample per country was cloned and sequenced. Based on the sequences of the 1.4-kb DNA products amplified by the first primer pair, specific primers were designed to complete each of the DNA A sequences. Computer-assisted sequence comparisons were performed with begomovirus sequences available in the laboratory at the Asian Vegetable Research and Development Center, Shanhua, Tainan, and in the GenBank sequence database. The five DNA species resembled DNA A of begomoviruses. For the detection of DNA B two degenerate primer pairs were used, DNABLC1/DNABLV2 and DNABLC2/DNABLV2 (DNABLC1: 5'-GTVAATGGRGTDCACTTCTG-3', DNABLC2: 5'-RGTDCACTT CTGYARGATGC-3', DNABLV2: 5'-GAGTAGTAGTGBAKGTTGCA-3'), which were specifically designed to amplify DNA B of Asian tomato geminiviruses. Only the virus associated with yellow leaf curl of tomato in Bangladesh was found to contain a DNA B component, which was detected with the DNABLC1/DNABLV2 primer pair. The DNA A sequence derived from the virus associated with tomato yellow leaf curl from Myanmar (GenBank Accession No. AF206674) showed highest sequence identity (94%) with tomato yellow leaf curl virus from Thailand (GenBank Accession No. X63015), suggesting that it is a closely related strain of this virus. The other four viruses were distinct begomoviruses, because their sequences shared less than 90% identity with known begomoviruses of tomato or other crops. The sequence derived from the virus associated with tomato yellow leaf curl from Vietnam (GenBank Accession No. AF264063) showed highest sequence identity (82%) with the virus associated with chili leaf curl from Malaysia (GenBank Accession No. AF414287), whereas the virus associated with yellow leaf curl symptoms in tomato in Bangladesh (GenBank Accession No. AF188481) had the highest sequence identity (88%) with a tobacco geminivirus from Yunnan, China (GenBank Accession No. AF240675). The sequence derived from the virus associated with tomato yellow leaf curl from Laos (GenBank Accession No. AF195782) had the highest sequence identity (88%) with the tomato begomovirus from Malaysia (GenBank Accession No. AF327436). This report provides further evidence of the great genetic diversity of tomato-infecting begomoviruses in Asia. Reference: M. R. Rojas et al. Plant Dis. 77:340, 1993.

Tomato yellow leaf curl virus, an emerging virus complex causing epidemics worldwide

Tomato yellow leaf curl (TYLC) is one of the most devastating viral diseases of cultivated tomato ( Lycopersicon esculentum) in tropical and subtropical regions worldwide, and losses of up to 100% are frequent. In many regions, TYLC is the main limiting factor in tomato production. The causal agents are a group of geminivirus species belonging to the genus Begomovirus of the family Geminiviridae, all of them named Tomato yellow leaf curl virus (TYLCV) ( sensu lato). There has been almost 40 years of research on TYLCV epidemics and intensive research programmes have been conducted to find solutions to the severe problem caused by these viruses. This paper provides an overview of the most outstanding achievements in the research on the TYLCV complex that could lead to more effective control strategies.