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Special Issue "Geminiviruses"

A special issue of Viruses (ISSN 1999-4915). This special issue belongs to the section "Viruses of Plants, Fungi and Protozoa".

Deadline for manuscript submissions: closed (31 August 2017)

Special Issue Editor

Guest Editor
Dr. Gian Paolo Accotto

Institute for Sustainable Plant Protection, C.N.R. (Istituto per la Protezione Sostenibile delle Piante - IPSP, C.N.R.), Strada delle Cacce, 73. Torino 10135, Italy
Website | E-Mail
Phone: (+39) 0113977.910
Fax: (+39) 011343809
Interests: geminiviruses; plant viruses; virus-plant interactions; resistance to plant viruses

Special Issue Information

Dear Colleagues,

Geminiviruses constitute a large and quickly evolving family of viruses infecting plants. New species, and even new genera, are being described, making them one of the most dynamic families among plant viruses. Their economic importance for crops is increasingly acknowledged, and global warming is moving these tropical viruses towards temperate regions. They have, thus far, escaped all attempts made to actually control field epidemics, including transgenic strategies.

Interesting studies have elucidated aspects of their relationships with the host and the insect vector.

Their nuclear replication makes these viruses an ideal tool for epigenetic studies. In a biotechnological perspective, geminiviruses can be developed into VIGS or expression vectors. They are, and will certainly be, interesting, for both basic and applied research, yielding more surprises in the future.

In this Special Issue of Viruses, we would like to include both research and review papers, providing an insight into the latest research on “Geminiviruses” and to highlight key outcomes.

Dr. Gian Paolo Accotto
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Viruses is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • diseases
  • morphology of virions and structure of genome
  • detection methods
  • recombination
  • evolution and phylogeny
  • transmission and vectors
  • replication and expression
  • plant-virus interactions
  • plant defense and resistance genes
  • silencing of viruses
  • satellite DNAs
  • viral vectors

Published Papers (10 papers)

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Research

Jump to: Review

Open AccessArticle Begomoviral Movement Protein Effects in Human and Plant Cells: Towards New Potential Interaction Partners
Viruses 2017, 9(11), 334; https://doi.org/10.3390/v9110334
Received: 9 October 2017 / Revised: 3 November 2017 / Accepted: 7 November 2017 / Published: 9 November 2017
Cited by 1 | PDF Full-text (15585 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Geminiviral single-stranded circular DNA genomes replicate in nuclei so that the progeny DNA has to cross both the nuclear envelope and the plasmodesmata for systemic spread within plant tissues. For intra- and intercellular transport, two proteins are required: a nuclear shuttle protein (NSP)
[...] Read more.
Geminiviral single-stranded circular DNA genomes replicate in nuclei so that the progeny DNA has to cross both the nuclear envelope and the plasmodesmata for systemic spread within plant tissues. For intra- and intercellular transport, two proteins are required: a nuclear shuttle protein (NSP) and a movement protein (MP). New characteristics of ectopically produced Abutilon mosaic virus (AbMV) MP (MPAbMV), either authentically expressed or fused to a yellow fluorescent protein or epitope tags, respectively, were determined by localization studies in mammalian cell lines in comparison to plant cells. Wild-type MPAbMV and the distinct MPAbMV: reporter protein fusions appeared as curled threads throughout mammalian cells. Co-staining with cytoskeleton markers for actin, intermediate filaments, or microtubules identified these threads as re-organized microtubules. These were, however, not stabilized by the viral MP, as demonstrated by nocodazole treatment. The MP of a related bipartite New World begomovirus, Cleome leaf crumple virus (ClLCrV), resulted in the same intensified microtubule bundling, whereas that of a nanovirus did not. The C-terminal section of MPAbMV, i.e., the protein’s oligomerization domain, was dispensable for the effect. However, MP expression in plant cells did not affect the microtubules network. Since plant epidermal cells are quiescent whilst mammalian cells are proliferating, the replication-associated protein RepAbMV protein was then co-expressed with MPAbMV to induce cell progression into S-phase, thereby inducing distinct microtubule bundling without MP recruitment to the newly formed threads. Co-immunoprecipitation of MPAbMV in the presence of RepAbMV, followed by mass spectrometry identified potential novel MPAbMV-host interaction partners: the peptidyl-prolyl cis-trans isomerase NIMA-interacting 4 (Pin4) and stomatal cytokinesis defective 2 (SCD2) proteins. Possible roles of these putative interaction partners in the begomoviral life cycle and cytoskeletal association modes are discussed. Full article
(This article belongs to the Special Issue Geminiviruses)
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Open AccessArticle Deep Sequencing Data and Infectivity Assays Indicate that Chickpea Chlorotic Dwarf Virus is the Etiological Agent of the “Hard Fruit Syndrome” of Watermelon
Viruses 2017, 9(11), 311; https://doi.org/10.3390/v9110311
Received: 13 September 2017 / Revised: 13 October 2017 / Accepted: 21 October 2017 / Published: 25 October 2017
Cited by 2 | PDF Full-text (1759 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
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
[...] Read more.
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. Full article
(This article belongs to the Special Issue Geminiviruses)
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Open AccessArticle Seed Transmission of Beet Curly Top Virus and Beet Curly Top Iran Virus in a Local Cultivar of Petunia in Iran
Viruses 2017, 9(10), 299; https://doi.org/10.3390/v9100299
Received: 12 September 2017 / Revised: 8 October 2017 / Accepted: 13 October 2017 / Published: 16 October 2017
Cited by 5 | PDF Full-text (2066 KB) | HTML Full-text | XML Full-text
Abstract
Beet curly top virus (BCTV) and beet curly top Iran virus (BCTIV) are known as the causal agents of curly top disease in beet and several other dicotyledonous plants in Iran. These viruses are transmitted by Circulifer species, and until now, there has
[...] Read more.
Beet curly top virus (BCTV) and beet curly top Iran virus (BCTIV) are known as the causal agents of curly top disease in beet and several other dicotyledonous plants in Iran. These viruses are transmitted by Circulifer species, and until now, there has been no confirmed report of their seed transmission. A percentage (38.2–78.0%) of the seedlings developed from the seeds of a petunia local cultivar under insect-free conditions showed stunting, interveinal chlorosis, leaf curling, and vein swelling symptoms, and were infected by BCTV when tested by PCR. Presence of BCTV in seed extracts of petunia local cultivar was confirmed by PCR and IC-PCR, followed by sequencing. Agroinoculation of curly top free petunia plants with a BCTV infectious clone resulted in BCTV infection of plants and their developed seeds. These results show the seed infection and transmission of BCTV in a local cultivar of petunia. Similar experiments performed with BCTIV showed that this virus is also seed transmissible in the same cultivar of petunia, although with a lower rate (8.8–18.5%). Seed transmission of curly top viruses may have significant implications in the epidemiology of these viruses. Full article
(This article belongs to the Special Issue Geminiviruses)
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Open AccessArticle Inference of a Geminivirus−Host Protein−Protein Interaction Network through Affinity Purification and Mass Spectrometry Analysis
Viruses 2017, 9(10), 275; https://doi.org/10.3390/v9100275
Received: 31 August 2017 / Revised: 20 September 2017 / Accepted: 22 September 2017 / Published: 25 September 2017
Cited by 1 | PDF Full-text (6568 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Viruses reshape the intracellular environment of their hosts, largely through protein-protein interactions, to co-opt processes necessary for viral infection and interference with antiviral defences. Due to genome size constraints and the concomitant limited coding capacity of viruses, viral proteins are generally multifunctional and
[...] Read more.
Viruses reshape the intracellular environment of their hosts, largely through protein-protein interactions, to co-opt processes necessary for viral infection and interference with antiviral defences. Due to genome size constraints and the concomitant limited coding capacity of viruses, viral proteins are generally multifunctional and have evolved to target diverse host proteins. Inference of the virus-host interaction network can be instrumental for understanding how viruses manipulate the host machinery and how re-wiring of specific pathways can contribute to disease. Here, we use affinity purification and mass spectrometry analysis (AP-MS) to define the global landscape of interactions between the geminivirus Tomato yellow leaf curl virus (TYLCV) and its host Nicotiana benthamiana. For this purpose, we expressed tagged versions of each of TYLCV-encoded proteins (C1/Rep, C2/TrAP, C3/REn, C4, V2, and CP) in planta in the presence of the virus. Using a quantitative scoring system, 728 high-confidence plant interactors were identified, and the interaction network of each viral protein was inferred; TYLCV-targeted proteins are more connected than average, and connect with other proteins through shorter paths, which would allow the virus to exert large effects with few interactions. Comparative analyses of divergence patterns between N. benthamiana and potato, a non-host Solanaceae, showed evolutionary constraints on TYLCV-targeted proteins. Our results provide a comprehensive overview of plant proteins targeted by TYLCV during the viral infection, which may contribute to uncovering the underlying molecular mechanisms of plant viral diseases and provide novel potential targets for anti-viral strategies and crop engineering. Interestingly, some of the TYLCV-interacting proteins appear to be convergently targeted by other pathogen effectors, which suggests a central role for these proteins in plant-pathogen interactions, and pinpoints them as potential targets to engineer broad-spectrum resistance to biotic stresses. Full article
(This article belongs to the Special Issue Geminiviruses)
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Open AccessArticle Engineered Disease Resistance in Cotton Using RNA-Interference to Knock down Cotton leaf curl Kokhran virus-Burewala and Cotton leaf curl Multan betasatellite Expression
Viruses 2017, 9(9), 257; https://doi.org/10.3390/v9090257
Received: 20 June 2017 / Revised: 8 August 2017 / Accepted: 30 August 2017 / Published: 14 September 2017
Cited by 1 | PDF Full-text (4565 KB) | HTML Full-text | XML Full-text
Abstract
Cotton leaf curl virus disease (CLCuD) is caused by a suite of whitefly-transmitted begomovirus species and strains, resulting in extensive losses annually in India and Pakistan. RNA-interference (RNAi) is a proven technology used for knockdown of gene expression in higher organisms and viruses.
[...] Read more.
Cotton leaf curl virus disease (CLCuD) is caused by a suite of whitefly-transmitted begomovirus species and strains, resulting in extensive losses annually in India and Pakistan. RNA-interference (RNAi) is a proven technology used for knockdown of gene expression in higher organisms and viruses. In this study, a small interfering RNA (siRNA) construct was designed to target the AC1 gene of Cotton leaf curl Kokhran virus-Burewala (CLCuKoV-Bu) and the βC1 gene and satellite conserved region of the Cotton leaf curl Multan betasatellite (CLCuMB). The AC1 gene and CLCuMB coding and non-coding regions function in replication initiation and suppression of the plant host defense pathway, respectively. The construct, , was transformed into cotton plants using the Agrobacterium-mediated embryo shoot apex cut method. Results from fluorescence in situ hybridization and karyotyping assays indicated that six of the 11 T1 plants harbored a single copy of the Vβ transgene. Transgenic cotton plants and non-transgenic (susceptible) test plants included as the positive control were challenge-inoculated using the viruliferous whitefly vector to transmit the CLCuKoV-Bu/CLCuMB complex. Among the test plants, plant Vβ-6 was asymptomatic, had the lowest amount of detectable virus, and harbored a single copy of the transgene on chromosome six. Absence of characteristic leaf curl symptom development in transgenic Vβ-6 cotton plants, and significantly reduced begomoviral-betasatellite accumulation based on real-time polymerase chain reaction, indicated the successful knockdown of CLCuKoV-Bu and CLCuMB expression, resulting in leaf curl resistant plants. Full article
(This article belongs to the Special Issue Geminiviruses)
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Open AccessArticle SGS3 Cooperates with RDR6 in Triggering Geminivirus-Induced Gene Silencing and in Suppressing Geminivirus Infection in Nicotiana Benthamiana
Viruses 2017, 9(9), 247; https://doi.org/10.3390/v9090247
Received: 10 August 2017 / Revised: 29 August 2017 / Accepted: 30 August 2017 / Published: 4 September 2017
Cited by 1 | PDF Full-text (2611 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
RNA silencing has an important role in defending against virus infection in plants. Plants with the deficiency of RNA silencing components often show enhanced susceptibility to viral infections. RNA-dependent RNA polymerase (RDRs) mediated-antiviral defense has a pivotal role in resistance to many plant
[...] Read more.
RNA silencing has an important role in defending against virus infection in plants. Plants with the deficiency of RNA silencing components often show enhanced susceptibility to viral infections. RNA-dependent RNA polymerase (RDRs) mediated-antiviral defense has a pivotal role in resistance to many plant viruses. In RDR6-mediated defense against viral infection, a plant-specific RNA binding protein, Suppressor of Gene Silencing 3 (SGS3), was also found to fight against some viruses in Arabidopsis. In this study, we showed that SGS3 from Nicotiana benthamiana (NbSGS3) is required for sense-RNA induced post-transcriptional gene silencing (S-PTGS) and initiating sense-RNA-triggered systemic silencing. Further, the deficiency of NbSGS3 inhibited geminivirus-induced endogenous gene silencing (GIEGS) and promoted geminivirus infection. During TRV-mediated NbSGS3 or N. benthamiana RDR6 (NbRDR6) silencing process, we found that their expression can be effectively fine-tuned. Plants with the knock-down of both NbSGS3 and NbRDR6 almost totally blocked GIEGS, and were more susceptible to geminivirus infection. These data suggest that NbSGS3 cooperates with NbRDR6 against GIEGS and geminivirus infection in N. benthamiana, which provides valuable information for breeding geminivirus-resistant plants. Full article
(This article belongs to the Special Issue Geminiviruses)
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Review

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Open AccessReview An Insight into Cotton Leaf Curl Multan Betasatellite, the Most Important Component of Cotton Leaf Curl Disease Complex
Viruses 2017, 9(10), 280; https://doi.org/10.3390/v9100280
Received: 29 August 2017 / Revised: 20 September 2017 / Accepted: 28 September 2017 / Published: 29 September 2017
Cited by 2 | PDF Full-text (2666 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Cotton leaf curl disease (CLCuD) is one of the most economically important diseases and is a constraint to cotton production in major producers, Pakistan and India. CLCuD is caused by monopartite plant viruses belonging to the family Geminiviridae (genus Begomovirus), in association
[...] Read more.
Cotton leaf curl disease (CLCuD) is one of the most economically important diseases and is a constraint to cotton production in major producers, Pakistan and India. CLCuD is caused by monopartite plant viruses belonging to the family Geminiviridae (genus Begomovirus), in association with an essential, disease-specific satellite, Cotton leaf curl Multan betasatellite (CLCuMuB) belonging to a newly-established family Tolecusatellitidae (genus Betasatellite). CLCuMuB has a small genome (ca. 1350 nt) with a satellite conserved region, an adenine-rich region and a single gene that encodes for a multifunctional βC1 protein. CLCuMuB βC1 protein has a major role in pathogenicity and symptom determination, and alters several host cellular functions like autophagy, ubiquitination, and suppression of gene silencing, to assist CLCuD infectivity. Efficient trans-replication ability of CLCuMuB with several monopartite and bipartite begomoviruses, is also associated with the rapid evolution and spread of CLCuMuB. In this article we comprehensively reviewed the role of CLCuMuB in CLCuD, focusing on the βC1 functions and its interactions with host proteins. Full article
(This article belongs to the Special Issue Geminiviruses)
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Open AccessReview The Incredible Journey of Begomoviruses in Their Whitefly Vector
Viruses 2017, 9(10), 273; https://doi.org/10.3390/v9100273
Received: 28 August 2017 / Revised: 13 September 2017 / Accepted: 18 September 2017 / Published: 24 September 2017
Cited by 6 | PDF Full-text (810 KB) | HTML Full-text | XML Full-text
Abstract
Begomoviruses are vectored in a circulative persistent manner by the whitefly Bemisia tabaci. The insect ingests viral particles with its stylets. Virions pass along the food canal and reach the esophagus and the midgut. They cross the filter chamber and the midgut into
[...] Read more.
Begomoviruses are vectored in a circulative persistent manner by the whitefly Bemisia tabaci. The insect ingests viral particles with its stylets. Virions pass along the food canal and reach the esophagus and the midgut. They cross the filter chamber and the midgut into the haemolymph, translocate into the primary salivary glands and are egested with the saliva into the plant phloem. Begomoviruses have to cross several barriers and checkpoints successfully, while interacting with would-be receptors and other whitefly proteins. The bulk of the virus remains associated with the midgut and the filter chamber. In these tissues, viral genomes, mainly from the tomato yellow leaf curl virus (TYLCV) family, may be transcribed and may replicate. However, at the same time, virus amounts peak, and the insect autophagic response is activated, which in turn inhibits replication and induces the destruction of the virus. Some begomoviruses invade tissues outside the circulative pathway, such as ovaries and fat cells. Autophagy limits the amounts of virus associated with these organs. In this review, we discuss the different sites begomoviruses need to cross to complete a successful circular infection, the role of the coat protein in this process and the sites that balance between virus accumulation and virus destruction. Full article
(This article belongs to the Special Issue Geminiviruses)
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Open AccessReview Tomato Leaf Curl New Delhi Virus: An Emerging Virus Complex Threatening Vegetable and Fiber Crops
Viruses 2017, 9(10), 264; https://doi.org/10.3390/v9100264
Received: 17 August 2017 / Revised: 13 September 2017 / Accepted: 20 September 2017 / Published: 21 September 2017
Cited by 5 | PDF Full-text (1744 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
The tomato leaf curl New Delhi virus (ToLCNDV) (genus Begomovirus, family Geminiviridae) represents an important constraint to tomato production, as it causes the most predominant and economically important disease affecting tomato in the Indian sub-continent. However, in recent years, ToLCNDV has
[...] Read more.
The tomato leaf curl New Delhi virus (ToLCNDV) (genus Begomovirus, family Geminiviridae) represents an important constraint to tomato production, as it causes the most predominant and economically important disease affecting tomato in the Indian sub-continent. However, in recent years, ToLCNDV has been fast extending its host range and spreading to new geographical regions, including the Middle East and the western Mediterranean Basin. Extensive research on the genome structure, protein functions, molecular biology, and plant–virus interactions of ToLCNDV has been conducted in the last decade. Special emphasis has been given to gene silencing suppression ability in order to counteract host plant defense responses. The importance of the interaction with DNA alphasatellites and betasatellites in the biology of the virus has been demonstrated. ToLCNDV genetic variability has been analyzed, providing new insights into the taxonomy, host adaptation, and evolution of this virus. Recombination and pseudorecombination have been shown as motors of diversification and adaptive evolution. Important progress has also been made in control strategies to reduce disease damage. This review highlights these various achievements in the context of the previous knowledge of begomoviruses and their interactions with plants. Full article
(This article belongs to the Special Issue Geminiviruses)
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Open AccessReview Geminiviruses and Plant Hosts: A Closer Examination of the Molecular Arms Race
Viruses 2017, 9(9), 256; https://doi.org/10.3390/v9090256
Received: 30 June 2017 / Revised: 2 September 2017 / Accepted: 6 September 2017 / Published: 15 September 2017
Cited by 6 | PDF Full-text (1119 KB) | HTML Full-text | XML Full-text
Abstract
Geminiviruses are plant-infecting viruses characterized by a single-stranded DNA (ssDNA) genome. Geminivirus-derived proteins are multifunctional and effective regulators in modulating the host cellular processes resulting in successful infection. Virus-host interactions result in changes in host gene expression patterns, reprogram plant signaling controls, disrupt
[...] Read more.
Geminiviruses are plant-infecting viruses characterized by a single-stranded DNA (ssDNA) genome. Geminivirus-derived proteins are multifunctional and effective regulators in modulating the host cellular processes resulting in successful infection. Virus-host interactions result in changes in host gene expression patterns, reprogram plant signaling controls, disrupt central cellular metabolic pathways, impair plant’s defense system, and effectively evade RNA silencing response leading to host susceptibility. This review summarizes what is known about the cellular processes in the continuing tug of war between geminiviruses and their plant hosts at the molecular level. In addition, implications for engineered resistance to geminivirus infection in the context of a greater understanding of the molecular processes are also discussed. Finally, the prospect of employing geminivirus-based vectors in plant genome engineering and the emergence of powerful genome editing tools to confer geminivirus resistance are highlighted to complete the perspective on geminivirus-plant molecular interactions. Full article
(This article belongs to the Special Issue Geminiviruses)
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