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The family Geminiviridae includes viruses with mono- or bipartite single-stranded, circular DNA genomes of 2.5-5.2 kb. They cause economically important diseases in most tropical and subtropical regions of the world. Geminiviruses infect dicot and monocot plants and are transmitted by insect vectors. DNA satellites are associated with some geminiviruses. This is a summary of the International Committee on Taxonomy of Viruses (ICTV) Report on the family Geminiviridae which is available at ictv.global/report/geminiviridae.

Background: Geminiviruses are circular, single-stranded viruses responsible for enormous crop loss worldwide. Rapid expansion of geminivirus diversity outweighs the continuous effort to control its spread. Geminiviruses channelize the host cell machinery in their favour by manipulating the gene expression, cell signalling, protein turnover, and metabolic reprogramming of plants. As a response to viral infection, plants have evolved to deploy various strategies to subvert the virus invasion and reinstate cellular homeostasis., Main Body: Numerous reports exploring various aspects of plant-geminivirus interaction portray the subtlety and flexibility of the host-pathogen dynamics. To leverage this pool of knowledge towards raising antiviral resistance in host plants, a comprehensive account of plant's defence response against geminiviruses is required. This review discusses the current knowledge of plant's antiviral responses exerted to geminivirus in the light of resistance mechanisms and the innate genetic factors contributing to the defence. We have revisited the defence pathways involving transcriptional and post-transcriptional gene silencing, ubiquitin-proteasomal degradation pathway, protein kinase signalling cascades, autophagy, and hypersensitive responses. In addition, geminivirus-induced phytohormonal fluctuations, the subsequent alterations in primary and secondary metabolites, and their impact on pathogenesis along with the recent advancements of CRISPR-Cas9 technique in generating the geminivirus resistance in plants have been discussed., Conclusions: Considering the rapid development in the field of plant-virus interaction, this review provides a timely and comprehensive account of molecular nuances that define the course of geminivirus infection and can be exploited in generating virus-resistant plants to control global agricultural damage., (© 2021. The Author(s).)

The family Cactaceae comprises a diverse group of typically succulent plants that are native to the American continent but have been introduced to nearly all other continents, predominantly for ornamental purposes. Despite their economic, cultural, and ecological importance, very little research has been conducted on the viral community that infects them. We previously identified a highly divergent geminivirus that is the first known to infect cacti. Recent research efforts in non-cultivated and asymptomatic plants have shown that the diversity of this viral family has been under-sampled. As a consequence, little is known about the effects and interactions of geminiviruses in many plants, such as cacti. With the objective to expand knowledge on the diversity of geminiviruses infecting cacti, we used previously acquired high-throughput sequencing results to search for viral sequences using BLASTx against a viral RefSeq protein database. We identified two additional sequences with similarity to geminiviruses, for which we designed abutting primers and recovered full-length genomes. From 42 cacti and five scale insects, we derived 42 complete genome sequences of a novel geminivirus species that we have tentatively named Opuntia virus 2 (OpV2) and 32 genomes of an Opuntia-infecting becurtovirus (which is a new strain of the spinach curly top Arizona virus species). Interspecies recombination analysis of the OpV2 group revealed several recombinant regions, in some cases spanning half of the genome. Phylogenetic analysis demonstrated that OpV2 is a novel geminivirus more closely related to viruses of the genus Curtovirus , which was further supported by the detection of three recombination events between curtoviruses and OpV2. Both OpV2 and Opuntia becurtoviruses were identified in mixed infections, which also included the previously characterized Opuntia virus 1. Viral quantification of the co-infected cactus plants compared with single infections did not show any clear trend in viral dynamics that might be associated with the mixed infections. Using experimental Rhizobium -mediated inoculations, we found that the initial accumulation of OpV2 is facilitated by co-infection with OpV1. This study shows that the diversity of geminiviruses that infect cacti is under-sampled and that cacti harbor diverse geminiviruses. The detection of the Opuntia becurtoviruses suggests spill-over events between viruses of cultivated species and native vegetation. The threat this poses to cacti needs to be further investigated.

Yield losses induced by a complex of begomoviruses are observed across all major tomato-producing areas in Brazil. Tomato severe rugose virus (ToSRV) is the most widespread begomovirus in the country. Conversely, tomato common mosaic virus (ToCmMV) displays a more restricted geographical distribution to areas associated with the Atlantic Rain Forest (ARF) biome, encompassing the States of Espírito Santo-ES, Minas Gerais-MG, and Rio de Janeiro-RJ. Here, we characterized 277 tomato-infecting isolates collected in fields located within the ARF biome from 2006 to 2018. ToSRV displayed the highest prevalence (n = 157), followed by ToCmMV (n = 95) and tomato interveinal chlorosis virus (n = 14). Four other begomoviruses were also detected, but with very low incidences. ToCmMV was the predominant begomovirus in the ARF biome up to 2014-2015 with very low ToSRV incidence. Subsequently, ToSRV became the most prevalent species in ES and RJ, but ToCmMV was still predominating in the "Zona da Mata" meso-region in MG. Due to the remarkable endemic distribution of ToCmMV, we carried out phylogeographical studies of this virus using information from all 28 available isolates with complete DNA-A sequences. The closest common ancestor of ToCmMV was more likely originated around Coimbra-MG area ≈ 25 years before the formal report of this viral species. So far, all surveys indicated tomatoes as the only natural hosts of ToCmMV with outbreaks occurring mainly (but not exclusively) in highland areas. ToSRV shows a more widespread incidence across both highland and lowland areas of the ARF biome.

Background: Cassava is an important food crop in tropical and sub-tropical regions worldwide. In Africa, cassava production is widely affected by cassava mosaic disease (CMD), which is caused by the African cassava mosaic geminivirus that is transmitted by whiteflies. Cassava breeders often use a single locus, CMD2, for introducing CMD resistance into susceptible cultivars. The CMD2 locus has been genetically mapped to a 10-Mbp region, but its organization and genes as well as their functions are unknown., Results: We report haplotype-resolved de novo assemblies and annotations of the genomes for the African cassava cultivar TME (tropical Manihot esculenta), which is the origin of CMD2, and the CMD-susceptible cultivar 60444. The assemblies provide phased haplotype information for over 80% of the genomes. Haplotype comparison identified novel features previously hidden in collapsed and fragmented cassava genomes, including thousands of allelic variants, inter-haplotype diversity in coding regions, and patterns of diversification through allele-specific expression. Reconstruction of the CMD2 locus revealed a highly complex region with nearly identical gene sets but limited microsynteny between the two cultivars., Conclusions: The genome maps of the CMD2 locus in both 60444 and TME3, together with the newly annotated genes, will help the identification of the causal genetic basis of CMD2 resistance to geminiviruses. Our de novo cassava genome assemblies will also facilitate genetic mapping approaches to narrow the large CMD2 region to a few candidate genes for better informed strategies to develop robust geminivirus resistance in susceptible cassava cultivars.

Begomoviruses are one of the major groups of plant viruses with an important economic impact on crop production in tropical and subtropical regions. The global spread of its polyphagous vector, the whitefly Bemisia tabaci , has contributed to the emergence and diversification of species within this genus. In this study, we found a putative novel begomovirus infecting tomato plants in Venezuela without a cognate DNA-B component. This begomovirus was genetically characterized and compared with related species. Furthermore, its infectivity was demonstrated by agroinoculation of infectious clones in tomato ( Solanum lycopersicum ) and Nicotiana benthamiana plants. The name Tomato twisted leaf virus (ToTLV) is proposed. ToTLV showed the typical genome organization of the DNA-A component of New World bipartite begomoviruses. However, the single DNA component of ToTLV was able to develop systemic infection in tomato and N. benthamiana plants, suggesting a monopartite nature of its genome. Interestingly, an additional open reading frame ORF was observed in ToTLV encompassing the intergenic region and the coat protein gene, which is not present in other closely related begomoviruses. A putative transcript from this region was amplified by strand-specific reverse transcription-PCR. Along with recent studies, our results showed that the diversity of monopartite begomoviruses from the New World is greater than previously thought.

Grapevine red blotch virus (GRBV) is suspected to alter berry ripening and chemistry. This study performed a physiological characterization of GRBV infected grapevines with attention to the factors leading to chemical changes during ripening of Cabernet Sauvignon in two rootstocks, 110R and 420A. RB(+) grapevines had transiently lower net photosynthesis; however, berry total soluble solids (TSS) accumulation was consistently reduced in the two years of study. Accumulation of anthocyanins and loss of titratable acidity and proanthocyanins were also delayed in RB(+) plants. However, the comparison of samples with the same TSS led to lower pH and anthocyanins content. The reduction in carbon import into berries under mild and transient reductions in carbon fixation suggested an impairment of translocation mechanisms with RB(+), leading into a desynchronization of ripening-related processes.

Throughout the world, geminiviruses cause devastating losses in economically important crops, including tomato, cotton, cassava, potato, chili, and cucumber; however, control mechanisms such as genetic resistance remain expensive and ineffective. CRISPR/Cas9 is an adaptive immunity mechanism used by prokaryotes to defend against invading nucleic acids of phages and plasmids. The CRISPR/Cas9 system has been harnessed for targeted genome editing in a variety of eukaryotic species, and in plants, CRISPR/Cas9 has been used to modify or introduce many traits, including virus resistance. Recently, we demonstrated that the CRISPR/Cas9 system could be used to engineer plant immunity against geminiviruses by directly targeting the viral genome for degradation. In this chapter, we describe a detailed method for engineering CRISPR/Cas9-mediated resistance against geminiviruses. This method may provide broad, durable viral resistance, as it can target conserved regions of the viral genome and can also be customized to emerging viral variants. Moreover, this method can be used in many crop species, as it requires little or no knowledge of the host plant's genome.

Begomoviruses (family Geminiviridae) are frequently associated with alphasatellites and betasatellites in the Old World. Tomato yellow leaf curl virus, one of the most damaging begomovirus species worldwide, was recently found associated with betasatellites in the eastern coast of the Mediterranean Sea, and in the Middle East region. Tomato yellow leaf curl virus (TYLCV)/betasatellite associations were shown to increase TYLCV virulence in experimental conditions. The sustainability of TYLCV/satellite associations in tomato was assessed here by estimating accumulation levels of satellites in comparison to TYLCV, vector transmission efficiency, and by testing how far the popular Ty-1 resistance gene used in most TYLCV-resistant tomato cultivars in the Mediterranean Basin is effective against betasatellites. Three satellites previously isolated from okra in Burkina Faso-of the species Cotton leaf curl Gezira betasatellite, Cotton leaf curl Gezira alphasatellite and Okra leaf curl Burkina Faso alphasatellite-were shown to accumulate at levels similar to, or higher than, the helper virus TYLCV-Mld in tomato plants from 32 to 150 days post inoculation (dpi). Cotton leaf curl Gezira betasatellite (CLCuGB) reduced TYLCV-Mld accumulation whereas alphasatellites did not. Transmission tests were performed with B. tabaci from plants infected with TYLCV-Mld/CLCuGB- or TYLCV-Mld/Okra leaf curl Burkina Faso alphasatellite. At 32 dpi, both satellites were transmitted to more than 50% of TYLCV-infected test plants. Betasatellite transmission, tested further with 150 dpi source plants was successful in more than 30% of TYLCV-infected test plants. Ty-1 resistant tomato plants co-infected with TYLCV (-Mld or -IL) and CLCuGB exhibited mild leaf curling and mosaic symptoms at the early stage of infection associated with a positive effect on TYLCV-IL accumulation, while resistant plants infected with TYLCV only, were asymptomatic. Together with previous experimental studies, these results further emphasize the potential risk of betasatellites to tomato cultivation, including with Ty-1 resistant cultivars., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Background: Morphogenic culture systems are central to crop improvement programs that utilize transgenic and genome editing technologies. We previously reported that CMD2-type cassava (Manihot esculenta) cultivars lose resistance to cassava mosaic disease (CMD) when passed through somatic embryogenesis. As a result, these plants cannot be developed as products for deployment where CMD is endemic such as sub-Saharan Africa or the Indian sub-continent., Result: In order to increase understanding of this phenomenon, 21 African cassava cultivars were screened for resistance to CMD after regeneration through somatic embryogenesis. Fifteen cultivars were shown to retain resistance to CMD through somatic embryogenesis, confirming that the existing transformation and gene editing systems can be employed in these genetic backgrounds without compromising resistance to geminivirus infection. CMD2-type cultivars were also subjected to plant regeneration via caulogenesis and meristem tip culture, resulting in 25-36% and 5-10% of regenerated plant lines losing resistance to CMD respectively., Conclusions: This study provides clear evidence that multiple morphogenic systems can result in loss of resistance to CMD, and that somatic embryogenesis per se is not the underlying cause of this phenomenon. The information described here is critical for interpreting genomic, transcriptomic and epigenomic datasets aimed at understanding CMD resistance mechanisms in cassava.

Predators influence the behaviour of prey and by doing so they potentially reduce pathogen transmission by a vector. Arthropod predators have been shown to reduce the consumption of plant biomass by pest herbivores, but their cascading non-consumptive effect on vector insects' feeding behaviour and subsequent pathogen transmission has not been investigated experimentally before. Here we experimentally examined predator-mediated pathogen transmission mechanisms using the plant pathogen Wheat Dwarf Virus that is transmitted by the leafhopper, Psammotettix alienus. We applied in situ hybridization to localize which leaf tissues were infected with transmitted virus DNA in barley host plants, proving that virus occurrence is restricted to phloem tissues. In the presence of the spider predator, Tibellus oblongus, we recorded the within leaf feeding behaviour of the herbivore using electrical penetration graph. The leafhopper altered its feeding behaviour in response to predation risk. Phloem ingestion, the feeding phase when virus acquisition occurs, was delayed and was less frequent. The phase when pathogen inoculation takes place, via the secretion of virus infected vector saliva, was shorter when predator was present. Our study thus provides experimental evidence that predators can potentially limit the spread of plant pathogens solely through influencing the feeding behaviour of vector organisms.

Background: Cassava is an important crop in Africa that is widely cultivated for its starchy tuberous root, which constitutes a major source of dietary carbohydrates. Cassava mosaic disease (CMD) is the most devastating disease affecting cassava in Africa and causes enormous losses in yield. In Benin, specifically, cultivars resistant to CMD are not commonly planted, and even when CMD is observed in fields, farmers do not implement control measures, presumably because they lack proper knowledge and training. Our study aimed to evaluate farmers' knowledge of CMD to determine whether there is consistency between farmers' criteria for selecting cassava cultivars and the currently CMD-recommended cassava varieties., Methods: We conducted structured interviews with 369 farmers in 20% of townships in each of three agro-ecological zones in Benin between November 2015 and February 2016. Farmers were selected randomly in each household, and their fields were assessed for CMD incidence and severity., Results: All farmers surveyed, representing a broad demographic pool with regard to education level, age group, and years of experience in cassava production, successfully recognized CMD symptoms in photos, but most (98.60%) said they did not know the causes and vectors of the disease. Most farmers (93.51%) reported that they obtain planting material from neighboring fields or their own fields. In total, 52 unique cultivars were identified, of which 3 (5.76%) were preferred based on their yield and precocity and 3 (5.76%) were preferred based on taste or ability for transformation. The assessment of disease incidence and severity showed that the areas most affected by CMD were Comè Township (37.77% of fields affected) and agro-ecological zone VIII (26.33%)., Conclusion: Farmers already know how to recognize the symptoms of CMD and could implement control measures against it if they are trained by researchers. Across all surveyed areas, we identified six preferred cultivars based on the four most commonly stated preference criteria (precocity, yield, gari, and taste. Our results suggest that farmers will be more likely to use CMD-resistant cultivars and clean plant material if the plants meet their existing preference criteria. We suggest that CMD-resistant cultivars will be embraced only if the recommended cultivars are strategically aligned with the characteristics desirable to the cassava farmers in each region.

Tomato mild yellow leaf curl Aragua virus (ToMYLCV) is a begomovirus first reported infecting tomato (Solanum lycopersicum) and milkweed (Euphorbia heterophylla) in Venezuela. In this study, a ToMYLCV isolate (Zulia-219) was completely sequenced and its host range was evaluated. The DNA-A and DNA-B components of isolate Zulia-219 showed 93 and 85% nucleotide sequence identity with the respective counterparts of the ToMYLCV type strain. According to current demarcation criteria for begomovirus species, Zulia-219 is a new strain of ToMYLCV. Interestingly, tomato plants inoculated with ToMYLCV Zulia-219 displayed severe symptoms, including severe chlorotic leaf curling, in contrast to mild symptoms associated with the type strain of this begomovirus. These results indicate potential risks associated with this new ToMYLCV strain for tomato production in Venezuela.

Chickpea chlorotic dwarf virus (CpCDV), a polyphagous mastrevirus, family Geminiviridae , has been recently linked to the onset of the "hard fruit syndrome" of watermelon, first described in Tunisia, that makes fruits unmarketable due to the presence of white hard portions in the flesh, chlorotic mottling on the rind, and an unpleasant taste. To investigate the etiological agent of this disease, total RNA extracted from symptomatic watermelon fruits was subjected to small RNA sequencing through next generation sequencing (NGS) techniques. Data obtained showed the presence of CpCDV and two other viral species. However, following validation through polymerase chain reaction (PCR), CpCDV was the only viral species consistently detected in all samples. Watermelon seedlings were then challenged by an agroinfectious CpCDV clone; several plants proved to be CpCDV-infected, and were able to produce fruits. CpCDV infected and replicated in watermelon fruits and leaves, leading to abnormality in fruits and in seed production, similar to those described in field. These results indicate that CpCDV is the etiological agent of the "hard fruit syndrome" of watermelon., Competing Interests: The authors declare no conflict of interest. The funding sponsors had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, and in the decision to publish the results.

At least five begomoviral species that cause leaf curl disease of cotton have emerged recently in Asia and Africa, reducing fiber quality and yield. The potential for the spread of these viruses to other cotton-vegetable growing regions throughout the world is extensive, owing to routine, global transport of alternative hosts of the leaf curl viruses, especially ornamentals. The research reported here describes the design and validation of polymerase chain reaction (PCR) primers undertaken to facilitate molecular detection of the two most-prevalent leaf curl-associated begomovirus-betasatellite complexes in the Indian Subcontinent and Africa, the Cotton leaf curl Kokhran virus-Burewala strain and Cotton leaf curl Gezira virus, endemic to Asia and Africa, respectively. Ongoing genomic diversification of these begomoviral-satellite complexes was evident based on nucleotide sequence alignments, and analysis of single nucleotide polymorphisms, both factors that created new challenges for primer design. The additional requirement for species and strain-specific, and betasatellite-specific primer design, imposes further constraints on primer design and validation due to the large number of related species and strains extant in 'core leaf curl virus complex', now with expanded distribution in south Asia, the Pacific region, and Africa-Arabian Peninsula that have relatively highly conserved coding and non-coding regions, which precludes much of the genome-betasatellite sequence when selecting primer 'targets'. Here, PCR primers were successfully designed and validated for detection of cloned viral genomes and betasatellites for representative 'core leaf curl' strains and species, distant relatives, and total DNA isolated from selected plant species. The application of molecular diagnostics to screen plant imports prior to export or release from ports of entry is expected to greatly reduce the likelihood of exotic leaf curl virus introductions that could dramatically affect the production of cotton as well as vegetable and ornamental crop hosts., (Copyright © 2017 Elsevier B.V. All rights reserved.)

In India, Bhendi yellow vein mosaic disease (BYVMD) is one of the most economically important diseases of bhendi/okra and is caused by a complex of monopartite begomovirus (Bhendi yellow vein mosaic virus-BYVMV) and betasatellite (Bhendi yellow vein betasatellite-BYVB). In this study, we have analyzed the role of possible evolutionary factors involved in the evolution of BYVMV and BYVB isolates. Evidence of inter-species and inter-strain recombination events was detected among the viral isolates, and majority of these recombinant isolates possess microsatellites in their genome. Recombination analysis suggests that cotton-infecting and bhendi-infecting begomoviruses probably share a recent common ancestor. In addition to genetic differentiation and gene flow, high degree of genetic variability was detected among the viral population. A strong purifying selection seems to be acting on the viral coding regions. The nucleotide substitution rate of V1 gene (for BYVMV) and βC1 gene (for BYVB) was estimated to be 7.55 × 10 -4 and 2.25 × 10 -3 nucleotide substitutions/site/year, respectively. The present study underlines that the evolution of BYVMD-associated viral components is driven by selection acting on the genetic variation generated by recombination and mutation.

Pea (Pisum sativum) plants exhibiting leaf distortion, yellowing, stunted growth and reduction in leaf size from Rampur, Nepal were shown to be infected by a begomovirus in association with betasatellites and alphasatellites. The begomovirus associated with the disease showed only low levels of nucleotide sequence identity (<91%) to previously characterized begomoviruses. This finding indicates that the pea samples were infected with an as yet undescribed begomovirus for which the name Pea leaf distortion virus (PLDV) is proposed. Two species of betasatellite were identified in association with PLDV. One group of sequences had high (>78%) nucleotide sequence identity to isolates of Ludwigia leaf distortion betasatellite (LuLDB), and the second group had less than 78% to all other betasatellite sequences. This showed PLDV to be associated with either LuLDB or a previously undescribed betasatellite for which the name Pea leaf distortion betasatellite is proposed. Two types of alphasatellites were identified in the PLDV-infected pea plants. The first type showed high levels of sequence identity to Ageratum yellow vein alphasatellite, and the second type showed high levels of identity to isolates of Sida yellow vein China alphasatellite. These are the first begomovirus, betasatellites and alphasatellites isolated from pea.

A recently characterized calmodulin-like protein is an endogenous RNA silencing suppressor that suppresses sense-RNA induced post-transcriptional gene silencing (S-PTGS) and enhances virus infection, but the mechanism underlying calmodulin-like protein-mediated S-PTGS suppression is obscure. Here, we show that a calmodulin-like protein from Nicotiana benthamiana (NbCaM) interacts with Suppressor of Gene Silencing 3 (NbSGS3). Deletion analyses showed that domains essential for the interaction between NbSGS3 and NbCaM are also required for the subcellular localization of NbSGS3 and NbCaM suppressor activity. Overexpression of NbCaM reduced the number of NbSGS3-associated granules by degrading NbSGS3 protein accumulation in the cytoplasm. This NbCaM-mediated NbSGS3 degradation was sensitive to the autophagy inhibitors 3-methyladenine and E64d, and was compromised when key autophagy genes of the phosphatidylinositol 3-kinase (PI3K) complex were knocked down. Meanwhile, silencing of key autophagy genes within the PI3K complex inhibited geminivirus infection. Taken together these data suggest that NbCaM acts as a suppressor of RNA silencing by degrading NbSGS3 through the autophagy pathway.

Aberrant viral RNAs produced in infected plant cells serve as templates for the synthesis of dsRNAs. The derived virus-related small interfering RNAs (siRNA) mediate cleavage of viral RNAs by post-transcriptional gene silencing (PTGS), thus blocking virus multiplication. Here, we identified ASYMMETRIC LEAVES2 (AS2) as a new component of plant P body complex which mediates mRNA decapping and degradation. We found that AS2 promotes DCP2 decapping activity, accelerates mRNA turnover rate, inhibits siRNA accumulation and functions as an endogenous suppressor of PTGS. Consistent with these findings, as2 mutant plants are resistant to virus infection whereas AS2 over-expression plants are hypersensitive. The geminivirus nuclear shuttle protein BV1 protein, which shuttles between nuclei and cytoplasm, induces AS2 expression, causes nuclear exit of AS2 to activate DCP2 decapping activity and renders infected plants more sensitive to viruses. These principles of gene induction and shuttling of induced proteins to promote mRNA decapping in the cytosol may be used by viral pathogens to weaken antiviral defenses in host plants.

Bemisia tabaci (Gennadius) is one of the economically most damaging insects to crops in tropical and subtropical regions. Severe damage is caused by feeding and more seriously by transmitting viruses. Those of the genus begomovirus (Geminiviridae) cause the most significant crop diseases and are transmitted by B. tabaci in a persistent circulative mode, a process which is largely unknown. To analyze the translocation and to identify critical determinants for transmission, two populations of B. tabaci MEAM1 were compared for transmitting Watermelon chlorotic stunt virus (WmCSV) and Tomato yellow leaf curl virus (TYLCV). Insect populations were chosen because of their high and respectively low virus transmission efficiency to compare uptake and translocation of virus through insects. Both populations harbored Rickettsia, Hamiltonella and Wolbachia in comparable ratios indicating that endosymbionts might not contribute to the different transmission rates. Quantification by qPCR revealed that WmCSV uptake and virus concentrations in midguts and primary salivary glands were generally higher than TYLCV due to higher virus contents of the source plants. Both viruses accumulated higher in insects from the efficiently compared to the poorly transmitting population. In the latter, virus translocation into the hemolymph was delayed and virus passage was impeded with limited numbers of viruses translocated. FISH analysis confirmed these results with similar virus distribution found in excised organs of both populations. No virus accumulation was found in the midgut lumen of the poor transmitter because of a restrained virus translocation. Results suggest that the poorly transmitting population comprised insects that lacked transmission competence. Those were selected to develop a population that lacks virus transmission. Investigations with insects lacking transmission showed that virus concentrations in midguts were reduced and only negligible virus amounts were found at the primary salivary glands indicating for a missing or modified receptor responsible for virus attachment or translocation.

Over the past three decades diseases caused by whitefly-transmitted geminiviruses (begomoviruses) have emerged to be important constraints to the production of solanaceous crops, particularly tomato (Solanum lycopersicum) and peppers (Capsicum spp.), in many tropical and subtropical regions of the world. The most studied of these is Tomato yellow leaf curl virus (TYLCV), which has spread to many other areas from its likely origin in the Mediterranean basin region. The virus is usually associated with the polyphagous and virus-vectoring-efficient B-biotype of its vector whitefly (Bemisia tabaci). However, in Southeast and East Asia, a wide variety of distinct local begomovirus species have been identified from tomato and pepper crops over this period, and TYLCV was detected in Japan only in about 1996, China in 2006 and Korea in 2008, despite B-biotype whiteflies being present in several of the countries of the region since at least the early 1990s. Continental Southeast Asia appears to be a major center of diversity for begomoviruses and some species may have spread across the region; Tomato yellow leaf curl Thailand virus (TYLCTHV) appears to have spread from the Thailand-Myanmar region into southern China and is now displacing the local tomato-infecting species in Taiwan, and Tomato yellow leaf curl Kanchanaburi virus (TYLCKaV) appears to have spread from the Thailand-Vietnam region to Java, Indonesia. Since many of the native tomato- or pepper-infecting begomoviruses and associated satellite DNAs have also been detected in local weed species, it seems likely that their ancestors originated in these weed hosts, but with the expansion and intensification of tomato and pepper production in the region, there was selection for recombinant or mutant forms with greater virulence on tomato and/or pepper. Expansion and intensification of these crops may also have resulted in increased populations of local, and if present, B- or Q-biotype whiteflies, aiding the increase and spread of local begomovirus species., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Four transgenic Arabidopsis thaliana lines carrying different reporter gene constructs based on split glucuronidase genes were used to monitor the frequency of somatic homologous recombination after geminivirus infections. Euphorbia mosaic virus and Cleome leaf crumple virus were chosen as examples, because they induce only mild symptoms and are expected to induce less general stress responses than other geminiviruses. After comparing the different plant lines and viruses as well as optimizing the infection procedure, Euphorbia mosaic virus enhanced recombination rates significantly in the transgenic reporter line 1445. The effect was tissue-specific in cells of the leaf veins as expected for this phloem-limited virus. The advantage for geminiviruses to activate a general recombination pathway is discussed with reference to an increased fitness by generating virus recombinants which have been observed frequently as an epidemiologic driving force., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Plants are routinely exposed to biotic and abiotic stresses to which they have evolved by synthesizing constitutive and induced defense compounds. Induced defense compounds are usually made, initially, at low levels; however, following further stimulation by specific kinds of biotic and abiotic stresses, they can be synthesized in relatively large amounts to abate the particular stress. cDNA microarray hybridization was used to identify an array of genes that were differentially expressed in tomato plants 15 d after they were exposed to feeding by nonviruliferous whiteflies or by viruliferous whiteflies carrying Pepper golden mosaic virus (PepGMV) (Begomovirus, Geminiviridae). Tomato plants inoculated by viruliferous whiteflies developed symptoms characteristic of PepGMV, whereas plants exposed to nonviruliferous whitefly feeding or nonwounded (negative) control plants exhibited no disease symptoms. The microarray analysis yielded over 290 spotted probes, with significantly altered expression of 161 putative annotated gene targets, and 129 spotted probes of unknown identities. The majority of the differentially regulated "known" genes were associated with the plants exposed to viruliferous compared with nonviruliferous whitefly feeding. Overall, significant differences in gene expression were represented by major physiological functions including defense-, pathogen-, photosynthesis-, and signaling-related responses and were similar to genes identified for other insect-plant systems. Viruliferous whitefly-stimulated gene expression was validated by real-time quantitative polymerase chain reaction of selected, representative candidate genes (messenger RNA): arginase, dehydrin, pathogenesis-related proteins 1 and -4, polyphenol oxidase, and several protease inhibitors. This is the first comparative profiling of the expression of tomato plants portraying different responses to biotic stress induced by viruliferous whitefly feeding (with resultant virus infection) compared with whitefly feeding only and negative control nonwounded plants exposed to neither. These results may be applicable to many other plant-insect-pathogen system interactions., (© The Author 2014. Published by Oxford University Press on behalf of the Entomological Society of America.)

In the Napa Valley of California, vineyards of 'Cabernet Franc' (CF) clone 214, 'Cabernet Sauvignon' clone 337, and 'Zinfandel' clone 1A (Z1A) with grapevines exhibiting foliar symptoms of red blotches, marginal reddening, and red veins that were accompanied by reduced sugar accumulation in fruit at harvest were initially suspected to be infected with leafroll-associated viruses. However, reverse-transcription polymerase chain reaction (PCR) tests were negative for all known leafroll-associated viruses, with the exception of Grapevine leafroll-associated virus 2 in Z1A. Metagenomic analysis of cDNA libraries obtained from double-stranded RNA enriched nucleic acid (NA) preparations from bark scrapings of dormant canes on an Illumina platform revealed sequences having a distant relationship with members of the family Geminiviridae. Sequencing of products obtained by PCR assays using overlapping primers and rolling circle amplification (RCA) confirmed the presence of a single circular genome of 3,206 nucleotides which was nearly identical to the genome of a recently reported Grapevine cabernet franc-associated virus found in declining grapevines in New York. We propose to call this virus "Grapevine red blotch-associated virus" (GRBaV) to describe its association with grapevine red blotch disease. Primers specific to GRBaV amplified a product of expected size (557 bp) from NA preparations obtained from petioles of several diseased source vines. Chip bud inoculations successfully transmitted GRBaV to test plants of CF, as confirmed by PCR analysis. This is the first report of a DNA virus associated with red blotch disease of grapevines in California.

DNA beta is a circular single-stranded satellite DNA associated with certain monopartite begomoviruses (family Geminiviridae) which causes economically important diseases such as cotton leaf curl disease. DNA beta contains a single gene, betaC1, which encodes a pathogenicity protein responsible for symptom production. Transient expression studies in Nicotiana tabacum using the beta-glucuronidase reporter gene driven by a betaC1 promoter-deletion series of the DNA beta associated with cotton leaf curl Multan virus identified a 68 nt region (between -139 and -207) which is important for betaC1 transcription. This 68 nt region contains a G-box (CACGTG) located 143 nt upstream of the betaC1 start codon. Mutation of the G-box resulted in a significant reduction in betaC1 promoter activity and DNA beta replication efficiency. In addition, the G-box motif was found to bind specifically to a protein(s) in nuclear extracts prepared from tobacco leaf tissues. Our results indicate that interaction of the G-box motif with host nuclear factors is important for efficient gene expression and replication of DNA beta.

The Tropical Whitefly IPM Project (TWFP) is an initiative of the Systemwide IPM Programme of the Consultative Group on International Agricultural Research (CGIAR), financed by the Department for International Development (DFID) of the United Kingdom, the Danish International Development Agency (DANIDA), the United States Department of Agriculture (USDA) and Agency for International Development (USAID), the Australian Centre for International Agricultural Research (ACIAR), and the New Zealand Agency for International Development (NZAID), to manage whitefly pests and whitefly-transmitted viruses in the Tropics. Participating CGIAR and other international centers include the Centre for International Tropical Agriculture (CIAT); the International Institute of Tropical Agriculture (IITA); The International Potato Centre (CIP); the Asian Vegetable Research and Development Centre (AVRDC); and the International Centre of Insect Physiology and Ecology (ICIPE), in close collaboration with the National Resources Institute (NRI-UK); national agricultural research institutions; agricultural universities; and advanced agricultural research laboratories in Africa, Asia, Europe, the Pacific Region, and the Americas. The TWFP was launched in 1996 as five separate but closely linked subprojects targeting: (1) Bemisia tabaci as a vector of viruses affecting cassava and sweet potato in sub-Saharan Africa (IITA, NRI, CIP, CIAT); (2) B. tabaci as a vector of viruses in mixed cropping systems of Mexico, Central America, and the Caribbean (CIAT); (3) B. tabaci as a vector of viruses in mixed cropping systems of eastern and southern Africa (ICIPE, AVRDC); (4) B. tabaci as a vector of viruses in mixed cropping systems of Southeast Asia (AVRDC); (5) Trialeurodes vaporariorum as a pest in mixed cropping systems of the Andean highlands (CIAT); and (6) whiteflies as pests of cassava in South America (CIAT). Diagnostic surveys conducted in Phase I (1997-2000) clearly showed that the two main whitefly pests in the Tropics are B. tabaci and, in the highlands, T. vaporariorum. Other whitefly species investigated by the TWFP included B. afer and Aleurotrachelus socialis. B. tabaci is the main vector of plant viruses inducing African cassava mosaic disease, sweet potato virus disease, bean golden mosaic disease, and many other diseases of horticultural crops, mainly tomato, hot and sweet peppers, squash, melon, and several other cucurbits. Genetic resistance was identified as the most important component of an IPM programme, followed by phytosanitary, cultural and legal measures. The two most important factors contributing to whitefly/virus epidemics were shown to be pesticide abuse and the use of virus-infected planting materials. Biological control is only effective in cropping systems with minimal or rational use of insecticides, and should be considered only as a complementary IPM strategy. Farmer education and technical assistance are considered the most critical steps toward the implementation of sustainable and economically viable IPM strategies in tropical countries affected by whitefly pests and whitefly-transmitted viruses.

Whitefly-transmitted geminiviruses are the most important constraint to the production of common bean and vegetable crops in the tropical lowlands and mid-altitude valleys of Latin America. Currently, over 30 distinct species of geminiviruses that are transmitted by the whitefly Bemisia tabaci infect common bean, tomato, pepper, cucurbits and other horticultural crops. A climate probability model (using FloraMap) was obtained using data from 304 geo-referenced locations where B. tabaci and geminiviruses cause significant damage. Clustering of the 304 points produced a simple model with two climatic variables: a dry season of at least 4 months each with less than 80 mm of rain and a mean temperature of the hottest month exceeding 21 degrees C. A modified Koeppen climate classification showed that 55% of the geminivirus-affected localities are in the tropical wet/dry region, 22% in the tropical and subtropical dry/humid climates and the remaining locations belonged to the wet equatorial and trade wind litoral climates. These findings contribute to understanding whitefly/geminivirus epidemics and implementation of sustainable integrated pest and disease management practices.

The proliferation and rapid dissemination of whitefly-transmitted viruses of important food and industrial crops in Latin America, have been the consequence of drastic changes in traditional cropping systems. Some of the expanding non-traditional cash and export crops, such as soybean and several vegetables, have served as suitable reproductive hosts for the whitefly Bemisia tabaci. This insect pest has been shown to transmit at least 20 different geminiviruses that affect different commercial and basic food crops in Latin America. This review summarizes the existing knowledge on this important group of viruses and their vector in this region.

Cassava mosaic disease (CMD), now known to be caused by cassava mosaic geminiviruses (Family Geminiviridae; Genus Begomovirus), was first reported in East Africa in 1894. Epidemics occurred in Madagascar and Uganda in the 1930s and 1940s, and more localised rapid spread of CMD was observed in parts of coastal Tanzania in the 1930s and coastal Kenya in the 1970s. During the 1990s, a major regional pandemic of an unusually severe form of CMD has expanded to affect parts of at least five countries, causing massive economic losses and destabilising food security. Mechanisms responsible for the development and progress of the pandemic have been described, and comparisons of epidemiological data for varieties grown throughout the period under review suggest that the recent pandemic has been characterised by rapid rates of CMD spread hitherto unknown in East Africa. A key factor in the genesis and spread of the pandemic has been the recombination between two distinct cassava mosaic geminiviruses to produce a novel and more virulent hybrid. Although such events may be common, the known history of CMD in East Africa suggests that the frequency with which they become epidemiologically significant is low. A corollary of this is that resistance, developed originally in Tanzania between 1934 and 1960, and utilized and supplemented at the International Institute of Tropical Agriculture, Nigeria, since 1971, is providing effective CMD control in current pandemic-affected areas of East Africa. Consequently, it is concluded that prospects for managing CMD in the 21st century are good, and that the approach adopted should build on the model of collaborative research and implementation that has been established in tackling the current CMD pandemic.

The mild climate of the Salinas Valley, CA lends itself well to a diverse agricultural industry. However, the diversity of weeds, crops and insect and fungal vectors also provide favorable conditions for plant virus disease development. This paper considers the incidence and management of several plant viruses that have caused serious epidemics and been significant in the agricultural development of the Salinas Valley during the 20th century. Beet curly top virus (BCTV) almost destroyed the newly established sugarbeet industry soon after its establishment in the 1870s. A combination of resistant varieties, cultural management of beet crops to provide early plant emergence and development, and a highly coordinated beet leafhopper vector scouting and spray programme have achieved adequate control of BCTV. These programmes were first developed by the USDA and still operate. Lettuce mosaic virus was first recognized as causing a serious disease of lettuce crops in the 1930s. The virus is still a threat but it is controlled by a lettuce-free period in December and a seed certification programme that allows only seed lots with less than one infected seed in 30000 to be grown. 'Virus Yellows' is a term used to describe a complex of yellows inducing viruses which affect mainly sugarbeet and lettuce. These viruses include Beet yellows virus and Beet western yellows virus. During the 1950s, the complex caused significant yield losses to susceptible crops in the Salinas Valley. A beet-free period was introduced and is still used for control. The fungus-borne rhizomania disease of sugarbeet caused by Beet necrotic yellow vein virus was first detected in Salinas Valley in 1983. Assumed to have been introduced from Europe, this virus has now become widespread in California wherever beets are grown and crop losses can be as high as 100%. Movement of infested soil and beets accounts for its spread throughout the beet-growing regions of the United States. Control of rhizomania involves several cultural practices, but the use of resistant varieties is the most effective and is necessary where soils are infested. Rhizomania-resistant varieties are now available that perform almost as well as the non-resistant varieties under non-rhizomania conditions. Another soil-borne disease termed lettuce dieback, caused by a tomato bushy stunt-like tombusvirus, has become economically limiting to romaine and leaf lettuce varieties. The virus has no known vector and it seems to be moved through infested soil and water. Heavy rains in the past 4 years have caused flooding of the Salinas River and lettuce fields along the river have been affected severely by dieback. Studies are now in progress to characterize this new virus and identify sources of resistance. Agriculture in the Salinas Valley continues to grow and diversify, driven by demands for 'clean', high quality food by the American public and for export. The major aspects of plant virus control, including crop-free periods, breeding for resistance, elimination of inoculum sources, and vector control will continue to be vital to this expansion. Undoubtedly, the advances in crop production through genetic manipulation and advances in pest management through biological control will eventually become an important part of agricultural improvement.

There is widespread evidence of plant viruses manipulating behavior of their insect vectors as a strategy to maximize infection of plants. Often, plant viruses and their insect vectors have multiple potential host plant species, and these may not overlap entirely. Moreover, insect vectors may not prefer plant species to which plant viruses are well-adapted. In such cases, can plant viruses manipulate their insect vectors to preferentially feed and oviposit on plant species, which are suitable for viral propagation but less suitable for themselves? To address this question, we conducted dual- and no-choice feeding studies (number and duration of probing events) and oviposition studies with non-viruliferous and viruliferous [carrying beet curly top virus (BCTV)] beet leafhoppers [Circulifer tenellus (Baker)] on three plant species: barley (Hordeum vulgare L.), ribwort plantain (Plantago lanceolata L.), and tomato (Solanum lycopersicum L.). Barley is not a host of BCTV, whereas ribwort plantain and tomato are susceptible to BCTV infection and develop a symptomless infection and severe curly top symptoms, respectively. Ribwort plantain plants can be used to maintain beet leafhopper colonies for multiple generations (suitable), whereas tomato plants cannot be used to maintain beet leafhopper colonies (unsuitable). Based on dual- and no-choice experiments, we demonstrated that BCTV appears to manipulate probing preference and behavior by beet leafhoppers, whereas there was no significant difference in oviposition preference. Simulation modeling predicted that BCTV infection rates would to be higher in tomato fields with barley compared with ribwort plantain as a trap crop. Simulation model results supported the hypothesis that manipulation of probing preference and behavior may increase BCTV infection in tomato fields. Results presented were based on the BCTV-beet leafhopper pathosystem, but the approach taken (combination of experimental studies with complementary simulation modeling) is widely applicable and relevant to other insect-vectored plant pathogen systems involving multiple plant species.

Flowering plants and mammals contain imprinted genes that are primarily expressed in the endosperm and placenta in a parent-of-origin manner. In this study, we show that early activation of the geminivirus genes C2 and C3 in Arabidopsis (Arabidopsis thaliana) plants, encoding a viral suppressor of RNA interference and a replication enhancer protein, respectively, is correlated with the transient vegetative expression of VARIANT IN METHYLATION5 (VIM5), an endosperm imprinted gene that is conserved in diverse plant species. VIM5 is a ubiquitin E3 ligase that directly targets the DNA methyltransferases MET1 and CMT3 for degradation by the ubiquitin-26S proteasome proteolytic pathway. Infection with Beet severe curly top virus induced VIM5 expression in rosette leaf tissues, possibly via the expression of the viral replication initiator protein, leading to the early activation of C2 and C3 coupled with reduced symmetric methylation in the C2-3 promoter and the onset of disease symptoms. These findings demonstrate how this small DNA virus recruits a host imprinted gene for the epigenetic activation of viral gene transcription. Our findings reveal a distinct strategy used by plant pathogens to exploit the host machinery in order to inhibit methylation-mediated defense responses when establishing infection.

Begomoviruses have emerged as a group of plant pathogens that cause devastating diseases in a wide range of crops in tropical and subtropical regions of the world. Betasatellites, the circular single-stranded DNA molecules with the size of almost half of that of the associated helper begomoviruses, are often essential for the production of typical disease symptoms in several virus-host systems. Association of betasatellites with begomoviruses results in more severe symptoms in the plants and affects the yield of numerous crops leading to huge agroeconomic losses. βC1, the only protein encoded by betasatellites, plays a multifaceted role in the successful establishment of infection. This protein counteracts the innate defence mechanisms of the host, like RNA silencing, ubiquitin-proteasome system and defence responsive hormones. In the last two decades, the molecular aspect of betasatellite pathogenesis has attracted much attention from the researchers worldwide, and reports have shown that βC1 protein aggravates the helper begomovirus disease complex by modulating specific host factors. This review discusses the molecular aspects of the pathogenesis of betasatellites, including various βC1-host factor interactions and their effects on the suppression of defence responses of the plants.

Grapevine red blotch-associated virus (GRBaV) is a major threat to the wine industry in the USA. GRBaV infections (aka red blotch disease) compromise crop yield and berry chemical composition, affecting the flavor and aroma properties of must and wine. In this study, we combined genome-wide transcriptional profiling with targeted metabolite analyses and biochemical assays to characterize the impact of the disease on red-skinned berry ripening and metabolism. Using naturally infected berries collected from two vineyards, we were able to identify consistent berry responses to GRBaV across different environmental and cultural conditions. Specific alterations of both primary and secondary metabolism occurred in GRBaV-infected berries during ripening. Notably, GRBaV infections of post-véraison berries resulted in the induction of primary metabolic pathways normally associated with early berry development (e.g. thylakoid electron transfer and the Calvin cycle), while inhibiting ripening-associated pathways, such as a reduced metabolic flux in the central and peripheral phenylpropanoid pathways. We show that this metabolic reprogramming correlates with perturbations at multiple regulatory levels of berry development. Red blotch caused the abnormal expression of transcription factors (e.g. NACs, MYBs, and AP2-ERFs) and elements of the post-transcriptional machinery that function during red-skinned berry ripening. Abscisic acid, ethylene, and auxin pathways, which control both the initiation of ripening and stress responses, were also compromised. We conclude that GRBaV infections disrupt normal berry development and stress responses by altering transcription factors and hormone networks, which result in the inhibition of ripening pathways involved in the generation of color, flavor, and aroma compounds.

The genus Begomovirus is the largest genus of the family Geminiviridae. Begomoviruses cause economically important diseases on dicotyledonous plants mainly in the tropical and subtropical regions worldwide. Their genomes are either mono- or bipartite circular ssDNAs (DNA-A and DNA-B) and all of them are transmitted by whitefly Bemisia tabaci in a persistent circulative manner (Brown et al. 2012). In this research, a common marshmallow (Malva sp.) plant sample with the begomovirus-like symptoms including crinkled and curling leaves (Fig. 1) was collected in Jiroft (Kerman province, south-eastern Iran). Total DNA was extracted using the CTAB method according to Zhang et al (1998) and subjected to next generation sequencing approach. Short read sequences were assembled using ABySS 2.2 software and compared to GenBank sequences. Sequence analysis of NGS data indicated that the common marshmallow sample infected with the cotton leaf curl Gezira virus (CLCuGV) and cotton leaf curl Gezira betasatellite. To confirm the sequence data, the full-length genome of CLCuGV and the associated betasatellite were amplified using rolling circle amplification method and the RCA kit (TempliPhi, GE Healthcare, USA) as described by Shepherd et al. (2006) followed by cloning and Sanger sequencing of ~3kb amplicon. Sequence data indicated that genomes of the Iranian CLCuGV isolate and the associated betasatellite are 2761 and 1355 nts in length and share 86.2-94.2 % and 82.05-96.5% nucleotide sequence identities with the corresponding sequences of GenBank isolates, respectively. To identify other CLCuGV hosts, a sunflower sample showing severe crinkling and cup-shaped leaves and five okra samples with severe leaf curl symptom were collected from greenhouse and/or open farms in Jiroft and Dezful (Khuzestan province), respectively. DNAs of samples were extracted and subjected to PCR assay using a specific primer pair (CLCuGVF/ CLCuGV-F) followed by detection of 730 bp in length amplicon. The betasatellite DNAs associated with the okra and sunflower samples were detected by RCA and sequencing of the resulted amplicons. It seems that due to special climatic conditions, i. e., having tropical and subtropical climatic conditions, Iran is one of the main centers of the prevalence of begomoviruses. Further studies including geographical distribution of the virus in other parts of the country, identification of other hosts, demonstration of the pathogenesis and study of the CLCuGV genome are in progress. This is the first report of the presence of CLCuGV and the associated betasatellite in Iran. [ABSTRACT FROM AUTHOR]

Beet curly top Iran virus (BCTIV), a member of the genus Becurtovirus, is one of the causal agents for curly top disease in tomato plants. Arbuscular mycorrhizal (AM) fungi provide nutrients for host plants and are associated with their improved growth. However, the impact of AM on infection by plant viruses is not well understood. In this study, the interaction between Funneliformis mosseae and BCTIV in a susceptible tomato cultivar (Early Eurbana) was investigated. In a completely randomized design experiment, tomato seedlings were inoculated with F. mosseae, and after 4 weeks, they were inoculated with an infectious clone of BCTIV. Four treatments were included: untreated control plants (C), BCTIV-infected plants (V), mycorrhizal plants (M) and BCTIV-infected mycorrhizal plants (MV). Results of symptom evaluation based on a disease severity index showed a higher disease severity in MV plants compared to V plants. Supporting this result, a higher level of virus accumulation was observed in MV plants and this became more significant after long-term infection. The expression of three defense-related genes including HSP90, RLK and PRP1 was attenuated in MV plants compared to V plants, which may explain the enhanced symptom production and viral accumulation in these plants. A similar percentage of root colonization by F. mosseae in M and MV plants indicated that root colonization was not affected by BCTIV infection. These results show that mycorrhizal symbiosis increases the susceptibility of tomato plants to virus infection and favors BCTIV accumulation and symptom production. [ABSTRACT FROM AUTHOR]

These symptoms are similar to those caused by I Tomato leaf curl New Delhi virus i (ToLCNDV), an important member of the genus I Begomovirus i , family I Geminiviridae i . The infected plants showed symptoms including apical leaf curl, vein swelling, severely stunted, wrinkled leaves, fruit shape and texture disorder and a conspicuous mosaic pattern (Figure 1-5). Keywords: Cucurbitaceae; Geminiviridae; Viral plant disease EN Cucurbitaceae Geminiviridae Viral plant disease 1 2 2 05/30/23 20230401 NES 230401 A leaf curl disease has been observed frequently in greenhouses where cucumber ( I Cucumis sativus i ), melon ( I Cucumis melo i ) and squash ( I Cucurbita pepo i ) are produced in Antalya since 2019. [Extracted from the article]

Mint (Mentha sp.; family: Lamiaceae) plants showing yellowing and stunting symptoms from Salalah, Dhofar region, Oman were shown to be infected by a monopartite begomovirus (family: Geminiviridae). Cloning and sequencing of restriction endonuclease digested rolling-circle amplified viral DNA identified a begomovirus associated with the symptomatic mint plants. Further analysis of complete sequences showed the virus to be a variant of the 'Oman' strain of Chili leaf curl virus (ChLCV-OM), a virus prevalent in a number of crops across Oman. However, the ChLCV-OM identified in mint has a recombination pattern distinct from all other ChLCV isolates. Additionally, PCR amplification and sequencing showed the mint plants to also harbour the betasatellite, Tomato leaf curl betasatellite (ToLCB). This is the first identification of ChLCV in association with ToLCB infecting mint. The distinct recombination pattern of ChLCV-OM from mint suggests that the host is epidemiologically important in the spread of ChLCV-OM to other crops in Oman. [ABSTRACT FROM AUTHOR]