Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    Defenses against Virus and Vector: A Phloem-Biological Perspective on RTM- and SLI1-Mediated Resistance to Potyviruses and Aphids
    Kloth, Karen J. ; Kormelink, Richard - \ 2020
    Viruses 12 (2020)2. - ISSN 1999-4915
    aphids - phloem - plant resistance - potyviruses

    Combining plant resistance against virus and vector presents an attractive approach to reduce virus transmission and virus proliferation in crops. RestrictedTobacco-etch virus Movement (RTM) genes confer resistance to potyviruses by limiting their long-distance transport. Recently, a close homologue of one of the RTM genes, SLI1, has been discovered but this gene instead confers resistance to Myzus persicae aphids, a vector of potyviruses. The functional connection between resistance to potyviruses and aphids, raises the question whether plants have a basic defense system in the phloem against biotic intruders. This paper provides an overview on restricted potyvirus phloem transport and restricted aphid phloem feeding and their possible interplay, followed by a discussion on various ways in which viruses and aphids gain access to the phloem sap. From a phloem-biological perspective, hypotheses are proposed on the underlying mechanisms of RTM- and SLI1-mediated resistance, and their possible efficacy to defend against systemic viruses and phloem-feeding vectors.

    Rescue of tomato spotted wilt virus entirely fromcomplementary DNA clones
    Feng, Mingfeng ; Cheng, Ruixiang ; Chen, Minglong ; Guo, Rong ; Li, Luyao ; Feng, Zhike ; Wu, Jianyan ; Xie, Li ; Hong, Jian ; Zhang, Zhongkai ; Kormelink, R.J.M. ; Tao, Xiaorong - \ 2020
    Proceedings of the National Academy of Sciences of the United States of America 117 (2020)2. - ISSN 0027-8424BioRxiv - p. 1181 - 1190.
    Negative-stranded/ambisense RNA viruses (NSVs) include not only dangerous pathogens of medical importance but also serious plant pathogens of agronomic importance. Tomato spotted wilt virus (TSWV) is one of the most important plant NSVs, infecting more than 1,000 plant species, and poses major threats to global food security. The segmented negative-stranded/ambisense RNA genomes of TSWV, however, have been a major obstacle to molecular genetic manipulation. In this study, we report the complete recovery of infectious TSWV entirely from complementary DNA (cDNA) clones. First, a replication- and transcription-competent minigenome replication system was established based on 35S-driven constructs of the S(−)-genomic (g) or S(+)-antigenomic (ag) RNA template, flanked by the 5′ hammerhead and 3′ ribozyme sequence of hepatitis delta virus, a nucleocapsid (N) protein gene and codon-optimized viral RNA-dependent RNA polymerase (RdRp) gene. Next, a movement-competent minigenome replication system was developed based on M(−)-gRNA, which was able to complement cell-to-cell and systemic movement of reconstituted ribonucleoprotein complexes (RNPs) of S RNA replicon. Finally, infectious TSWV and derivatives carrying eGFP reporters were rescued in planta via simultaneous expression of full-length cDNA constructs coding for S(+)-agRNA, M(−)-gRNA, and L(+)-agRNA in which the glycoprotein gene sequence of M(−)-gRNA was optimized. Viral rescue occurred with the addition of various RNAi suppressors including P19, HcPro, and γb, but TSWV NSs interfered with the rescue of genomic RNA. This reverse genetics system for TSWV now allows detailed molecular genetic analysis of all aspects of viral infection cycle and pathogenicity.
    Cellular RNA Hubs: Friends and Foes of Plant Viruses
    Xu, Min ; Mazur, Magdalena J. ; Tao, Xiaorong ; Kormelink, Richard - \ 2020
    Molecular Plant-Microbe Interactions 33 (2020)1. - ISSN 0894-0282 - p. 40 - 54.
    RNA granules are dynamic cellular foci that are widely spread in eukaryotic cells and play essential roles in cell growth and development, and immune and stress responses. Different types of granules can be distinguished, each with a specific function and playing a role in, for example, RNA transcription, modification, processing, decay, translation, and arrest. By means of communication and exchange of (shared) components, they form a large regulatory network in cells. Viruses have been reported to interact with one or more of these either cytoplasmic or nuclear granules, and act either proviral, to enable and support viral infection and facilitate viral movement, or antiviral, protecting or clearing hosts from viral infection. This review describes an overview and recent progress on cytoplasmic and nuclear RNA granules and their interplay with virus infection, first in animal systems and as a prelude to the status and current developments on plant viruses, which have been less well studied on this thus far.
    Ty-1, a universal resistance gene against geminiviruses that is compromised by co-replication of a betasatellite
    Voorburg, Corien M. ; Yan, Zhe ; Bergua-Vidal, Maria ; Wolters, Anne Marie A. ; Bai, Yuling ; Kormelink, Richard - \ 2020
    Molecular Plant Pathology 21 (2020)2. - ISSN 1464-6722 - p. 160 - 172.
    beet curly top virus - betasatellite - geminivirus - resistance - RNA interference - tomato yellow leaf curl virus - Ty-1

    Tomato yellow leaf curl virus (TYLCV), a begomovirus, causes large yield losses and breeding for resistance is an effective way to combat this viral disease. The resistance gene Ty-1 codes for an RNA-dependent RNA polymerase and has recently been shown to enhance transcriptional gene silencing of TYLCV. Whereas Ty-1 was earlier shown to also confer resistance to a bipartite begomovirus, here it is shown that Ty-1 is probably generic to all geminiviruses. A tomato Ty-1 introgression line, but also stable transformants of susceptible tomato cv. Moneymaker and Nicotiana benthamiana (N. benthamiana) expressing the Ty-1 gene, exhibited resistance to begomoviruses as well as to the distinct, leafhopper-transmitted beet curly top virus, a curtovirus. Stable Ty-1 transformants of N. benthamiana and tomato showed fewer symptoms and reduced viral titres on infection compared to wild-type plants. TYLCV infections in wild-type N. benthamiana plants in the additional presence of a betasatellite led to increased symptom severity and a consistent, slightly lowered virus titre relative to the high averaged levels seen in the absence of the betasatellite. On the contrary, in Ty-1 transformed N. benthamiana viral titres increased in the presence of the betasatellite. The same was observed when these Ty-1-encoding plants were challenged with TYLCV and a potato virus X construct expressing the RNA interference suppressor protein βC1 encoded by the betasatellite. The resistance spectrum of Ty-1 and the durability of the resistance are discussed in light of antiviral RNA interference and viral counter defence strategies.

    Novel mucosal vaccination strategies against spring viraemia of carp virus in common carp
    Goldman, Mark ; Tacchi, L. ; Kormelink, R.J.M. ; Wells, J.M. ; Forlenza, M. - \ 2019
    - p. 49 - 49.
    Virus Latency and the Impact on Plants
    Takahashi, Hideki ; Fukuhara, Toshiyuki ; Kitazawa, Haruki ; Kormelink, Richard - \ 2019
    Frontiers in Microbiology 10 (2019). - ISSN 1664-302X
    Plant viruses are thought to be essentially harmful to the lives of their cultivated crop hosts. In most cases studied, the interaction between viruses and cultivated crop plants negatively affects host morphology and physiology, thereby resulting in disease. Native wild/non-cultivated plants are often latently infected with viruses without any clear symptoms. Although seemingly non-harmful, these viruses pose a threat to cultivated crops because they can be transmitted by vectors and cause disease. Reports are accumulating on infections with latent plant viruses that do not cause disease but rather seem to be beneficial to the lives of wild host plants. In a few cases, viral latency involves the integration of full-length genome copies into the host genome that, in response to environmental stress or during certain developmental stages of host plants, can become activated to generate and replicate episomal copies, a transition from latency to reactivation and causation of disease development. The interaction between viruses and host plants may also lead to the integration of partial-length segments of viral DNA genomes or copy DNA of viral RNA genome sequences into the host genome. Transcripts derived from such integrated viral elements (EVEs) may be beneficial to host plants, for example, by conferring levels of virus resistance and/or causing persistence/latency of viral infections. Studies on viral latency in wild host plants might help us to understand and elucidate the underlying mechanisms of latency and provide insights into the raison d’être for viruses in the lives of plants.
    A functional investigation of the suppression of CpG and UpA dinucleotide frequencies in plant RNA virus genomes
    Ibrahim, Ahmad ; Fros, Jelke ; Bertran, Andre ; Sechan, Ferdyansyah ; Odon, Valerie ; Torrance, Leslie ; Kormelink, Richard ; Simmonds, Peter - \ 2019
    Scientific Reports 9 (2019)1. - ISSN 2045-2322

    Frequencies of CpG and UpA dinucleotides in most plant RNA virus genomes show degrees of suppression comparable to those of vertebrate RNA viruses. While pathways that target CpG and UpAs in HIV-1 and echovirus 7 genomes and restrict their replication have been partly characterised, whether an analogous process drives dinucleotide underrepresentation in plant viruses remains undetermined. We examined replication phenotypes of compositionally modified mutants of potato virus Y (PVY) in which CpG or UpA frequencies were maximised in non-structural genes (including helicase and polymerase encoding domains) while retaining protein coding. PYV mutants with increased CpG dinucleotide frequencies showed a dose-dependent reduction in systemic spread and pathogenicity and up to 1000-fold attenuated replication kinetics in distal sites on agroinfiltration of tobacco plants (Nicotiana benthamiana). Even more extraordinarily, comparably modified UpA-high mutants displayed no pathology and over a million-fold reduction in replication. Tobacco plants with knockdown of RDP6 displayed similar attenuation of CpG- and UpA-high mutants suggesting that restriction occurred independently of the plant siRNA antiviral responses. Despite the evolutionary gulf between plant and vertebrate genomes and encoded antiviral strategies, these findings point towards the existence of novel virus restriction pathways in plants functionally analogous to innate defence components in vertebrate cells.

    Paving the Way to Tospovirus Infection: Multilined Interplays with Plant Innate Immunity
    Zhu, Min ; Grinsven, Irene Louise Van; Kormelink, Richard ; Tao, Xiaorong - \ 2019
    Annual Review of Phytopathology 57 (2019). - ISSN 0066-4286 - p. 41 - 62.
    Antiviral RNAi - Effector/avirulence determinant - NLR - R gene - tospovirus - Viral RNA silencing suppressor

    Tospoviruses are among the most important plant pathogens and cause serious crop losses worldwide. Tospoviruses have evolved to smartly utilize the host cellular machinery to accomplish their life cycle. Plants mount two layers of defense to combat their invasion. The first one involves the activation of an antiviral RNA interference (RNAi) defense response. However, tospoviruses encode an RNA silencing suppressor that enables them to counteract antiviral RNAi. To further combat viral invasion, plants also employ intracellular innate immune receptors (e.g., Sw-5b and Tsw) to recognize different viral effectors (e.g., NSm and NSs). This leads to the triggering of a much more robust defense against tospoviruses called effector-Triggered immunity (ETI). Tospoviruses have further evolved their effectors and can break Sw-5b-/Tsw-mediated resistance. The arms race between tospoviruses and both layers of innate immunity drives the coevolution of host defense and viral genes involved in counter defense. In this review, a state-of-The-Art overview is presented on the tospoviral life cycle and the multilined interplays between tospoviruses and the distinct layers of defense.

    Plant viruses in plant molecular pharming: Toward the use of enveloped viruses
    Ibrahim, Ahmad ; Odon, Valerie ; Kormelink, Richard - \ 2019
    Frontiers in Plant Science 10 (2019). - ISSN 1664-462X
    Biotechnology - Non-enveloped viruses - Plant molecular pharming - Plant rhabdoviruses - Recombinant vaccines - Virus like particles

    Plant molecular pharming has emerged as a reliable platform for recombinant protein expression providing a safe and low-cost alternative to bacterial and mammalian cells-based systems. Simultaneously, plant viruses have evolved from pathogens to molecular tools for recombinant protein expression, chimaeric viral vaccine production, and lately, as nanoagents for drug delivery. This review summarizes the genesis of viral vectors and agroinfection, the development of non-enveloped viruses for various biotechnological applications, and the on-going research on enveloped plant viruses.

    Tomato Chlorotic Spot Virus (TCSV) Putatively Incorporated a Genomic Segment of Groundnut Ringspot Virus (GRSV) Upon a Reassortment Event
    Silva, João Marcos Fagundes ; Oliveira, Athos Silva de; Almeida, Mariana Martins Severo de; Kormelink, Richard ; Nagata, Tatsuya ; Resende, Renato Oliveira - \ 2019
    Viruses 11 (2019)2. - ISSN 1999-4915
    groundnut ringspot virus - reassortment - tomato chlorotic spot virus - tospovirus - virus evolution

    Tomato chlorotic spot virus (TCSV) and groundnut ringspot virus (GRSV) share several genetic and biological traits. Both of them belong to the genus Tospovirus (family Peribunyaviridae), which is composed by viruses with tripartite RNA genome that infect plants and are transmitted by thrips (order Thysanoptera). Previous studies have suggested several reassortment events between these two viruses, and some speculated that they may share one of their genomic segments. To better understand the intimate evolutionary history of these two viruses, we sequenced the genomes of the first TCSV and GRSV isolates ever reported. Our analyses show that TCSV and GRSV isolates indeed share one of their genomic segments, suggesting that one of those viruses may have emerged upon a reassortment event. Based on a series of phylogenetic and nucleotide diversity analyses, we conclude that the parental genotype of the M segment of TCSV was either eliminated due to a reassortment with GRSV or it still remains to be identified.

    Taxonomy of the order Bunyavirales : second update 2018
    Maes, Piet ; Adkins, Scott ; Alkhovsky, Sergey V. ; Avšič-Županc, Tatjana ; Ballinger, Matthew J. ; Bente, Dennis A. ; Beer, Martin ; Bergeron, Éric ; Blair, Carol D. ; Briese, Thomas ; Buchmeier, Michael J. ; Burt, Felicity J. ; Calisher, Charles H. ; Charrel, Rémi N. ; Choi, Il Ryong ; Clegg, J.C.S. ; Torre, Juan Carlos de la; Lamballerie, Xavier de; DeRisi, Joseph L. ; Digiaro, Michele ; Drebot, Mike ; Ebihara, Hideki ; Elbeaino, Toufic ; Ergünay, Koray ; Fulhorst, Charles F. ; Garrison, Aura R. ; Gāo, George Fú ; Gonzalez, Jean Paul J. ; Groschup, Martin H. ; Günther, Stephan ; Haenni, Anne Lise ; Hall, Roy A. ; Hewson, Roger ; Hughes, Holly R. ; Jain, Rakesh K. ; Jonson, Miranda Gilda ; Junglen, Sandra ; Klempa, Boris ; Klingström, Jonas ; Kormelink, Richard ; Lambert, Amy J. ; Langevin, Stanley A. ; Lukashevich, Igor S. ; Marklewitz, Marco ; Martelli, Giovanni P. ; Mielke-Ehret, Nicole ; Mirazimi, Ali ; Mühlbach, Hans Peter ; Naidu, Rayapati ; Zhang, Yong Zhen - \ 2019
    Archives of Virology 164 (2019)3. - ISSN 0304-8608 - p. 927 - 941.

    In October 2018, the order Bunyavirales was amended by inclusion of the family Arenaviridae, abolishment of three families, creation of three new families, 19 new genera, and 14 new species, and renaming of three genera and 22 species. This article presents the updated taxonomy of the order Bunyavirales as now accepted by the International Committee on Taxonomy of Viruses (ICTV).

    Identification and characterization of a new class of Tomato spotted wilt virus isolates that break Tsw-based resistance in a temperature-dependent manner
    Ronde, D. de; Lohuis, D. ; Kormelink, R. - \ 2019
    Plant Pathology 68 (2019)1. - ISSN 0032-0862 - p. 60 - 71.
    Capsicum - NSs protein - RNA-silencing suppressor - temperature-sensitive resistance-breaking - Tomato spotted wilt virus - Tsw-based resistance

    The single dominant Tsw resistance gene from Capsicum chinense against the Tomato spotted wilt orthotospovirus (TSWV) is temperature sensitive, i.e. the resistance fails to function at or above 32 °C. This study describes a new class of temperature-sensitive resistance-breaking TSWV isolates that induce Tsw-mediated resistance at T < 28 °C but at T ≥ 28 °C break this resistance. The NSs genes from these isolates were cloned and expressed to be analysed for RNA silencing suppressor (RSS) activity and the ability to induce a Tsw-mediated hypersensitive response (HR) in C. chinense and Capsicum annuum (Tsw+). Unlike in viral infection, transient expression of some of the NSs proteins at standard temperatures (22 °C) did not induce Tsw-mediated HR, although varying degrees of RSS activity were observed. Attempts to express and test the NSs proteins for functionality at an elevated temperature through agroinfiltration remained unsuccessful. The NSs proteins of some TSWV resistance-breaking (RB) isolates were analysed and found to lack amino acid residues that were previously shown to be important for RNA silencing suppression and avirulence. This study describes a new class of resistance-breaking TSWV isolates that may be of importance for breeders and growers and for which the underlying mechanism still remains unknown.

    Alstroemeria yellow spot virus (AYSV) : a new orthotospovirus species within a growing Eurasian clade
    Hassani-Mehraban, A. ; Dullemans, A.M. ; Verhoeven, J.Th.J. ; Roenhorst, J.W. ; Peters, D. ; Vlugt, R.A.A. van der; Kormelink, R. - \ 2019
    Archives of Virology 164 (2019)1. - ISSN 0304-8608 - p. 117 - 126.

    An orthotospovirus distinct from all other orthotospoviruses was isolated from naturally infected alstroemeria plants. Disease symptoms caused by this virus mainly consisted of yellow spots on the leaves based on which the name alstroemeria yellow spot virus (AYSV) was coined. A host range analysis was performed and a polyclonal antiserum was produced against purified AYSV ribonucleoproteins which only reacted with the homologous antigen and not with any other (established or tentative) orthotospovirus from a selection of American and Asian species. Upon thrips transmission assays the virus was successfully transmitted by a population of Thrips tabaci. The entire nucleotide sequence of the M and S RNA segments was elucidated by a conventional cloning and sequencing strategy, and contained 4797 respectively 2734 nucleotides (nt). Simultaneously, a next generation sequencing (NGS) approach (RNAseq) was employed and generated contigs covering the entire viral tripartite RNA genome. In addition to the M and S RNA nucleotide sequences, the L RNA (8865 nt) was obtained. The nucleocapsid (N) gene encoded by the S RNA of this virus consisted of 819 nucleotides with a deduced N protein of 272 amino acids and by comparative sequence alignments to other established orthotospovirus species showed highest homology (69.5% identity) to the N protein of polygonum ringspot virus. The data altogether support the proposal of AYSV as a new orthotospovirus species within a growing clade of orthotospoviruses that seem to share the Middle East basin as a region of origin.

    Genome packaging of the Bunyavirales
    Wichgers Schreur, Paul J. ; Kormelink, Richard ; Kortekaas, Jeroen - \ 2018
    Current Opinion in Virology 33 (2018). - ISSN 1879-6257 - p. 151 - 155.

    The order Bunyavirales comprises nine families of enveloped, negative-strand RNA viruses. Depending on the family and genus, bunyaviruses (i.e. now referring to all members of the Bunyavirales) contain genomes consisting of two to six segments. Each genome segment is encapsidated by multiple copies of the nucleocapsid (N) protein and one or a few molecules of the viral polymerase, forming so-called ribonucleoproteins (RNPs). Incorporation of RNPs into virions is mediated by the interaction of N with the cytoplasmic tails of the structural glycoproteins. Although some selectivity exists in the packaging of RNPs into virions, which seems to be driven by the 5′ and 3′-untranslated regions of the genomic RNA segments, evidence is accumulating that bunyavirus genome packaging is a stochastic process.

    The Sw-5 gene cluster : Tomato breeding and research toward orthotospovirus disease control
    Oliveira, Athos S. de; Boiteux, Leonardo S. ; Kormelink, Richard ; Resende, Renato O. - \ 2018
    Frontiers in Plant Science 9 (2018). - ISSN 1664-462X
    NB-LRR - NLR - Orthotospovirus - Resistance - Sw-5 - Sw-5b - Tomato

    The Sw-5 gene cluster encodes protein receptors that are potentially able to recognize microbial products and activate signaling pathways that lead to plant cell immunity. Although there are several Sw-5 homologs in the tomato genome, only one of them, named Sw-5b, has been extensively studied due to its functionality against a wide range of (thrips-transmitted) orthotospoviruses. The Sw-5b gene is a dominant resistance gene originally from a wild Peruvian tomato that has been used in tomato breeding programs aiming to develop cultivars with resistance to these viruses. Here, we provide an overview starting from the first reports of Sw-5 resistance, positional cloning and the sequencing of the Sw-5 gene cluster from resistant tomatoes and the validation of Sw-5b as the functional protein that triggers resistance against orthotospoviruses. Moreover, molecular details of this plant–virus interaction are also described, especially concerning the roles of Sw-5b domains in the sensing of orthotospoviruses and in the signaling cascade leading to resistance and hypersensitive response.

    Taxonomy of the family Arenaviridae and the order Bunyavirales : update 2018
    Maes, Piet ; Alkhovsky, Sergey V. ; Bào, Yīmíng ; Beer, Martin ; Birkhead, Monica ; Briese, Thomas ; Buchmeier, Michael J. ; Calisher, Charles H. ; Charrel, Rémi N. ; Choi, Il Ryong ; Clegg, Christopher S. ; Torre, Juan Carlos de la; Delwart, Eric ; DeRisi, Joseph L. ; Bello, Patrick L. Di; Serio, Francesco Di; Digiaro, Michele ; Dolja, Valerian V. ; Drosten, Christian ; Druciarek, Tobiasz Z. ; Du, Jiang ; Ebihara, Hideki ; Elbeaino, Toufic ; Gergerich, Rose C. ; Gillis, Amethyst N. ; Gonzalez, Jean Paul J. ; Haenni, Anne Lise ; Hepojoki, Jussi ; Hetzel, Udo ; Hồ, Thiện ; Hóng, Ní ; Jain, Rakesh K. ; Jansen van Vuren, Petrus ; Jin, Qi ; Jonson, Miranda Gilda ; Junglen, Sandra ; Keller, Karen E. ; Kemp, Alan ; Kipar, Anja ; Kondov, Nikola O. ; Koonin, Eugene V. ; Kormelink, Richard ; Korzyukov, Yegor ; Krupovic, Mart ; Lambert, Amy J. ; Laney, Alma G. ; LeBreton, Matthew ; Lukashevich, Igor S. ; Marklewitz, Marco ; Markotter, Wanda ; Martelli, Giovanni P. ; Martin, Robert R. ; Mielke-Ehret, Nicole ; Mühlbach, Hans Peter ; Navarro, Beatriz ; Ng, Terry Fei Fan ; Nunes, Márcio Roberto Teixeira ; Palacios, Gustavo ; Pawęska, Janusz T. ; Peters, Clarence J. ; Plyusnin, Alexander ; Radoshitzky, Sheli R. ; Romanowski, Víctor ; Salmenperä, Pertteli ; Salvato, Maria S. ; Sanfaçon, Hélène ; Sasaya, Takahide ; Schmaljohn, Connie ; Schneider, Bradley S. ; Shirako, Yukio ; Siddell, Stuart ; Sironen, Tarja A. ; Stenglein, Mark D. ; Storm, Nadia ; Sudini, Harikishan ; Tesh, Robert B. ; Tzanetakis, Ioannis E. ; Uppala, Mangala ; Vapalahti, Olli ; Vasilakis, Nikos ; Walker, Peter J. ; Wáng, Guópíng ; Wáng, Lìpíng ; Wáng, Yànxiăng ; Wèi, Tàiyún ; Wiley, Michael R. ; Wolf, Yuri I. ; Wolfe, Nathan D. ; Wú, Zhìqiáng ; Xú, Wénxìng ; Yang, Li ; Yāng, Zuòkūn ; Yeh, Shyi Dong ; Zhāng, Yǒng Zhèn ; Zhèng, Yàzhōu ; Zhou, Xueping ; Zhū, Chénxī ; Zirkel, Florian ; Kuhn, Jens H. - \ 2018
    Archives of Virology 163 (2018)8. - ISSN 0304-8608 - p. 2295 - 2310.
    In 2018, the family Arenaviridae was expanded by inclusion of 1 new genus and 5 novel species. At the same time, the recently established order Bunyavirales was expanded by 3 species. This article presents the updated taxonomy of the family Arenaviridae and the order Bunyavirales as now accepted by the International Committee on Taxonomy of Viruses (ICTV) and summarizes additional taxonomic proposals that may affect the order in the near future.
    Survey of the response of 82 domestic landraces of Zea mays to cucumber mosaic virus (CMV) reveals geographical region-related resistance to CMV in Japan
    Takahashi, H. ; Tian, A. ; Miyashita, S. ; Kanayama, Y. ; Ando, S. ; Kormelink, R. - \ 2018
    Plant Pathology 67 (2018)6. - ISSN 0032-0862 - p. 1401 - 1415.
    Cucumber mosaic virus - Hypersensitive response - Monocot - Necrotic local lesions - Virus resistance - Zea mays
    Zea mays has been historically imported to Japan via two independent geographical routes: into southern Japan by trading with Europe in the 16th century and into northern Japan by import from North America in the 19th century. Breeding to genetically improve on quality traits and high yields has led to the current domestic landraces in each region. In a survey of 82 domestic landraces, nine out of 38 landraces originating from southern Japan showed complete immunity to cucumber mosaic virus yellow strain (CMV(Y)) without the formation of necrotic local lesions (NLLs). In contrast, three out of 44 landraces originating from northern Japan developed NLLs, but revealed no systemic spread of the virus. Due to the absence of good documentation on NLL formation in Z. mays, the response of domestic landraces Aso-1 and Aso-3, originating from Ibaraki in northern Japan, to a challenge with CMV(Y) and CMV(Ma-1) was further analysed. Aso-3 only formed NLL in response to CMV(Y) but not to CMV(Ma-1). Moreover, in CMV(Y)-inoculated Aso-3, virus spread was restricted to the primary infection site and the expression of defence-related genes was up-regulated, whereas Aso-1 became systemically infected with either CMV(Y) or CMV(Ma-1). The response of Aso-3 to CMV(Y) was inherited as a single dominant trait. Together, these results pointed towards the induction of hypersensitive response (HR)-mediated resistance to CMV(Y) in Aso-3. Although HR-mediated resistance to viruses has been studied mainly in dicots, the pathosystem CMV-Z. mays may provide a model to investigate HR-mediated resistance to viruses in monocot plants.
    The cap snatching of segmented negative sense rna viruses as a tool to map the transcription start sites of heterologous co-infecting viruses
    Lin, Wenzhong ; Qiu, Ping ; Jin, Jing ; Liu, Shunmin ; Islam, Saif Ul ; Yang, Jinguang ; Zhang, Jie ; Kormelink, Richard ; Du, Zhenguo ; Wu, Zujian - \ 2017
    Frontiers in Microbiology 8 (2017)DEC. - ISSN 1664-302X
    Cap-snatching - Co-infection - Geminivirus - Rice stripe virus - SNSV - Tenuivirus - TSS
    Identification of the transcription start sites (TSSs) of a virus is of great importance to understand and dissect the mechanism of viral genome transcription but this often requires costly and laborious experiments. Many segmented negative-sense RNA viruses (sNSVs) cleave capped leader sequences from a large variety of mRNAs and use these cleaved leaders as primers for transcription in a conserved process called cap snatching. The recent developments in high-throughput sequencing have made it possible to determine most, if not all, of the capped RNAs snatched by a sNSV. Here, we show that rice stripe tenuivirus (RSV), a plant-infecting sNSV, co-infects Nicotiana benthamiana with two different begomoviruses and snatches capped leader sequences from their mRNAs. By determining the 5' termini of a single RSV mRNA with high-throughput sequencing, the 5' ends of almost all the mRNAs of the co-infecting begomoviruses could be identified and mapped on their genomes. The findings in this study provide support for the using of the cap snatching of sNSVs as a tool to map viral TSSs.
    Biochemical analysis of NSs from different tospoviruses
    Hedil, Marcio ; Ronde, Dryas de; Kormelink, Richard - \ 2017
    Virus Research 242 (2017). - ISSN 0168-1702 - p. 149 - 155.
    dsRNA - EMSA - NSs - RNA silencing - siRNA - Tospovirus

    Tospoviruses suppress antiviral RNA interference by coding for an RNA silencing suppressor (NSs) protein. Previously, using NSs-containing crude plant and insect cell extracts, the affinity of NSs for double-stranded (ds)RNA molecules was demonstrated by electrophoretic mobility shifts assays (EMSAs). While NSs from tomato spotted wilt virus (TSWV) and groundnut ringspot virus (GRSV) were able to bind small and long dsRNA molecules, the one from tomato yellow ring virus (TYRV), a distinct Asian tospovirus, only bound small dsRNA. Here, using bacterially expressed and purified NSs from GRSV and TYRV, it is shown that they are both able to bind to small and long dsRNA. Binding of siRNAs by NSs revealed two consecutive shifts, i.e. a first shift at low NSs concentrations followed by a second larger one at higher concentrations. When NSs of TSWV resistance inducing (RI) and resistance breaking (RB) isolates were analyzed using extracts from infected plants only a major siRNA shift was observed. In contrast, plant extracts containing the respective transiently expressed NSs proteins showed only the lower shift with NSsRI but no shift with NSsRB. The observed affinity for RNA duplexes, as well as the two-stepwise shift pattern, is discussed in light of NSs as a suppressor of silencing and its importance for tospovirus infection.

    The NSm proteins of phylogenetically related tospoviruses trigger Sw-5b–mediated resistance dissociated of their cell-to-cell movement function
    Leastro, Mikhail Oliveira ; Oliveira, Athos Silva De; Pallás, Vicente ; Sánchez-Navarro, Jesús A. ; Kormelink, Richard ; Resende, Renato Oliveira - \ 2017
    Virus Research 240 (2017). - ISSN 0168-1702 - p. 25 - 34.
    Avr - Hypersensitive response - NS protein - Resistance - Sw-5b gene - Tospovirus

    The cell-to-cell movement protein (NSM) in members of the tospovirus species Tomato spotted wilt virus (TSWV) has been recently identified as the effector of the single dominant Sw-5b resistance gene from tomato (Solanum lycopersicum L.). Although most TSWV isolates shows a resistance-inducing (RI) phenotype, regular reports have appeared on the emergence of resistance-breaking (RB) isolates in tomato fields, and suggested a strong association with two point mutations (C118Y and T120N) in the NSM protein. In this study the Sw-5b gene has been demonstrated to confer not only resistance against TSWV but to members of five additional, phylogenetically-related tospovirus species classified within the so-called “American” evolutionary clade, i.e. Alstroemeria necrotic streak virus (ANSV), Chrysanthemum stem necrosis virus (CSNV), Groundnut ringspot virus (GRSV), Impatiens necrotic spot virus (INSV) and Tomato chlorotic spot virus (TCSV). Remarkably, a member of the species Bean necrotic mosaic virus (BeNMV), a recently discovered tospovirus classified in a distinct American subclade and circulating on the American continent, did not trigger a Sw-5b-mediated hypersensitive (HR) response. Introduction of point mutations C118Y and T120N into the NSM protein of TSWV, TCSV and CSNV abrogated the ability to trigger Sw-5b-mediated HR in both transgenic-N. benthamiana and tomato isolines harboring the Sw-5b gene whereas it had no effect on BeNMV NSM. Truncated versions of TSWV NSM lacking motifs associated with tubule formation, cell-to-cell or systemic viral movement were made and tested for triggering of resistance. HR was still observed with truncated NSM proteins lacking 50 amino acids (out of 301) from either the amino- or carboxy-terminal end. These data altogether indicate the importance of amino acid residues C118 and T120 in Sw-5b-mediated HR only for the NSM proteins from one cluster of tospoviruses within the American clade, and that the ability to support viral cell-to-cell movement is not required for effector functionality.

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