Entwicklung, Optimierung und Erprobung von Nachweisverfahren von Viren an Apfel und Untersuchungen zur Ätiologie der Gummiholzkrankheit (ARW)

[no abstract

Harnessed viruses in the age of metagenomics and synthetic biology: an update on infectious clone assembly and biotechnologies of plant viruses

[EN] Recent metagenomic studies have provided an unprecedented wealth of data, which are revolutionizing our understanding of virus diversity. A redrawn landscape highlights viruses as active players in the phytobiome, and surveys have uncovered their positive roles in environmental stress tolerance of plants. Viral infectious clones are key tools for functional characterization of known and newly identified viruses. Knowledge of viruses and their components has been instrumental for the development of modern plant molecular biology and biotechnology. In this review, we provide extensive guidelines built on current synthetic biology advances that streamline infectious clone assembly, thus lessening a major technical constraint of plant virology. The focus is on generation of infectious clones in binary T-DNA vectors, which are delivered efficiently to plants by Agrobacterium. We then summarize recent applications of plant viruses and explore emerging trends in microbiology, bacterial and human virology that, once translated to plant virology, could lead to the development of virus-based gene therapies for ad hoc engineering of plant traits. The systematic characterization of plant virus roles in the phytobiome and next-generation virus-based tools will be indispensable landmarks in the synthetic biology roadmap to better crops.We are grateful to Catherine Mark for editorial assistance. We apologize to all colleagues whose relevant publications have not been cited because of space constraints or involuntary forgetfulness. F.P. is supported by a postdoctoral fellowship from the Academia Sinica (Taiwan); J.-A.D. is funded by grant BIO2017-83184-R from the Ministerio de Ciencia, Innovacion y Universidades (Spain). The authors declare no conflict of interest.Pasin, F.; Menzel, W.; Daròs, J. (2019). Harnessed viruses in the age of metagenomics and synthetic biology: an update on infectious clone assembly and biotechnologies of plant viruses. Plant Biotechnology Journal. 17(6):1010-1026. https://doi.org/10.1111/pbi.13084S1010102617

Viruserkrankungen in Möhren - gegenwärtige Probleme und verfügbare Nachweismethoden

An apparently new virus disease of carrots (Daucus carota) has gained increasing importance in Germany. The complex of symptoms consisting of leaf reddening, plant stunting, hairy and rat tailed roots is thought to be caused by viral infections. Particularly the main carrot growing areas in Lower Saxony are adversely affected. In field surveys in 2003 about 30 % symptomatic plants were observed with average weight losses of about 30 %. In severe cases symptom-related yield reduction was estimated to be 17 % on-farm, which corresponded to a monetary loss of up to 600 €/ha. In 2004 up to 6 % of the plants displayed virus like symptoms. Varietal differences in susceptibility were observed. In general, late maturing varieties for processing showed more symptoms than early maturing fresh market varietes. However, this was not consistent in all cases. At present eight different carrot viruses have been isolated and partially characterized. Antisera to Carrot yellow leaf virus (CYLV, Closterovirus), Carrot thin leaf virus (CTLV, Potyvirus), Carrot red leaf virus (CtRLV, Luteovirus), and the Anthriscus strain of Parsnip yellow fleck virus (PYFV, Sequivirus) are now commercially available for serological analysis of carrot samples. Our provisional experimental data indicate that CtRLV is highly variable and the causal agents typically associated with the carrot motley dwarf (CMD) disease complex may differ in Germany from those reported in the literature. Further analyses of single and multiple infections with their corresponding symptoms under controlled conditions will be necessary to identify the relevant environmental conditions leading to economic losses

Hydrology in the Sea of Marmara during the last 23 ka : implications for timing of Black Sea connections and sapropel deposition

Author Posting. © American Geophysical Union, 2010. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Paleoceanography 25 (2010): PA1205, doi:10.1029/2009PA001735.Sediments deposited under lacustrine and marine conditions in the Sea of Marmara hold a Late Quaternary record for water exchange between the Black Sea and the Mediterranean Sea. Here we report a multiproxy data set based on oxygen and strontium isotope results obtained from carbonate shells, major and trace elements, and specific organic biomarker measurements, as well as a micropaleontological study from a 14C-dated sediment core retrieved from the Sea of Marmara. Pronounced changes occurred in δ18O and 87Sr/86Sr values at the fresh and marine water transition, providing additional information in relation to micropaleontological data. Organic biomarker concentrations documented the marine origin of the sapropelic layer while changes in n-alkane concentrations clearly indicated an enhanced contribution for organic matter of terrestrial origin before and after the event. When compared with the Black Sea record, the results suggest that the Black Sea was outflowing to the Sea of Marmara from the Last Glacial Maximum until the warmer Bølling-Allerød. The first marine incursion in the Sea of Marmara occurred at 14.7 cal ka B.P. However, salinification of the basin was gradual, indicating that Black Sea freshwaters were still contributing to the Marmara seawater budget. After the Younger Dryas (which is associated with a high input of organic matter of terrestrial origin) both basins were disconnected, resulting in a salinity increase in the Sea of Marmara. The deposition of organic-rich sapropel that followed was mainly related to enhanced primary productivity characterized by a reorganization of the phytoplankton population.We acknowledge support from INSU and the French Polar Institute IPEV

Codivergence of Mycoviruses with Their Hosts

BACKGROUND: The associations between pathogens and their hosts are complex and can result from any combination of evolutionary events such as codivergence, switching, and duplication of the pathogen. Mycoviruses are RNA viruses which infect fungi and for which natural vectors are so far unknown. Thus, lateral transfer might be improbable and codivergence their dominant mode of evolution. Accordingly, mycoviruses are a suitable target for statistical tests of virus-host codivergence, but inference of mycovirus phylogenies might be difficult because of low sequence similarity even within families. METHODOLOGY: We analyzed here the evolutionary dynamics of all mycovirus families by comparing virus and host phylogenies. Additionally, we assessed the sensitivity of the co-phylogenetic tests to the settings for inferring virus trees from their genome sequences and approximate, taxonomy-based host trees. CONCLUSIONS: While sequence alignment filtering modes affected branch support, the overall results of the co-phylogenetic tests were significantly influenced only by the number of viruses sampled per family. The trees of the two largest families, Partitiviridae and Totiviridae, were significantly more similar to those of their hosts than expected by chance, and most individual host-virus links had a significant positive impact on the global fit, indicating that codivergence is the dominant mode of virus diversification. However, in this regard mycoviruses did not differ from closely related viruses sampled from non-fungus hosts. The remaining virus families were either dominated by other evolutionary modes or lacked an apparent overall pattern. As this negative result might be caused by insufficient taxon sampling, the most parsimonious hypothesis still is that host-parasite evolution is basically the same in all mycovirus families. This is the first study of mycovirus-host codivergence, and the results shed light not only on how mycovirus biology affects their co-phylogenetic relationships, but also on their presumable host range itself

Collaboratories

No abstract.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/34569/1/1440360103_ftp.pd

Immunocapture of virions with virus-specific antibodies prior to high-throughput sequencing effectively enriches for virus-specific sequences.

Virus discovery based on high-throughput sequencing relies on enrichment for virus sequences prior to library preparation to achieve a sufficient number of viral reads. In general, preparations of double-stranded RNA or total RNA preparations treated to remove rRNA are used for sequence enrichment. We used virus-specific antibodies to immunocapture virions from plant sap to conduct cDNA synthesis, followed by library preparation and HTS. For the four potato viruses PLRV, PVY, PVA and PYV, template preparation by virion immunocapture provided a simpler and less expensive method than the enrichment of total RNA by ribosomal depletion. Specific enrichment of viral sequences without an intermediate amplification step was achieved, and this high coverage of sequences across the viral genomes was important to identify rare sequence variations. Using this approach, the first complete genome sequence of a potato yellowing virus isolate (PYV, DSMZ PV-0706) was determined in this study. PYV can be confidently assigned as a distinct species in the genus Ilarvirus

The status of Cucumber vein yellowing virus in Iran

Yellowing symptoms of greenhouse- and open field-grown cucurbit crops are becoming increasingly important in many cucurbit growing regions of the world, and particularly in Iran. A survey was conducted from 2011 to 2012 in eight major cucurbit growing regions in Iran. Yellowing and specifically vein clearing symptoms were observed in many cucumber plants grown in greenhouses and open fields, suggesting the presence of Cucumber vein yellowing virus (CVYV, genus Ipomovirus, family Potyviridae). The identification of CVYV was carried out with a specific triple-antibody sandwich enzyme-linked immunosorbent assay (TAS-ELISA) and reverse transcription (RT)-PCR. CVYV was detected in 42% of the collected samples, in all surveyed provinces, except Bushehr. CVYV was also detected in melon and cucumber crops grown in open fields. These results indicate that CVYV is widely distributed on these two cucurbit species in the major cucumber growing areas of Iran. CVYV positive samples were also tested, using DAS-ELISA, for the presence of Cucurbit chlorotic yellows virus (CCYV) and Cucurbit yellow stunting disorder virus (CYSDV), two criniviruses reported previously to occur in Iran. Double or triple infections of CCYV and CYSDV occurred in 49 of 166 of the CVYV-infected plants. The CVYV and CCYV combined infections were more prevalent than CVYV and CYSDV combined infections. TAS-ELISA positive samples were used to mechanically inoculate healthy cucumber plants, and mild vein yellowing was observed on the inoculated leaves. Identical symptoms were also observed on whitefly inoculated healthy cucumber plants. The presence of CVYV in mechanically and whitefly inoculated plants was confirmed by TAS-ELISA and RT-PCR. Sequence analysis revealed that the Iranian isolate of CVYV was more closely related to Spanish isolates than to isolates from Jordan. Phylogenetic analysis showed that CVYV isolates can be divided into two phylogenetic groups (I and II). Despite the close vicinity of Jordan to Iran, the Iranian CVYV isolate clustered with Spanish isolates in group I and not with the Jordanian isolates of group II

Vermeidung von Viruserkrankungen (Möhrenröte) im Ökologischen Möhrenanbau: a) Status Quo Analysen, b) Entwicklung eines Virusnachweises und c) Erarbeitung von Strategien zur Lösung bestehender Probleme im Ökologischen Landbau

Für ein offenbar neues Krankheitsbild („Möhrenröte“) im ökologischen Möhrenanbau, bestehend aus Rotfärbungen des Laubes, gestauchten Herzblättern, Wurzelbärtigkeit und sog. „Rattenschwänzen“, werden Viruserkrankungen verantwortlich gemacht. Im Projekt wurden die Teilziele Virusanalytik, Status-Quo-Analysen und Lösungsstrategien wie folgt bearbeitet: Virusanalytik: Es konnten mindestens 8 verschiedene Viren identifiziert werden, nämlich 2-3 Stämme bzw. Arten aus dem Luteoviruskomplex Carrot red leaf virus (CtRLV), die Umbraviren Carrot mottle mimic virus/Carrot mottle virus, das Closterovirus Carrot yellow leaf virus, der Anthriscus-Stamm des Sequivirus Parsnip yellow fleck virus, das Potyvirus Carrot thin leaf virus, jeweils ein bisher nicht beschriebenes Carlavirus und Vitivirus sowie ein bisher unbekanntes „Beny“-ähnliches Virus. „Beny“-Virus und CtRLV wurden am häufigsten nachgewiesen. Ein konventionell erzeugtes Serum gegen CTLV wurde hergestellt und steht auch für PYFV in Aussicht. Während die Herstellung von Antiseren nach Immunisierung mit bakteriell exprimierten Hüllprotein für die CtRLV-Varianten nicht erfolgreich verlief, konnte auf diesem Wege ein Antiserum gegen CYLV erzeugt werden. Der hohe Anteil latent CtRLV-infizierter, symptomloser Pflanzen zeigt aber, dass offenbar noch andere bisher unbekannte Faktoren für die Symptomausprägung eine Rolle spielen. Die bundesweiten Status-Quo-Analysen zur Symptomatik ergaben als Hauptverbreitungsgebiete alle Anbauregionen mit intensivem Möhrenanbau, insbesondere die niedersächsische Region südlich Bremen. In Ernteproben wiesen symptomatische Rübenkörper ca. 30% Gewichtsverlust auf. Qualitätseinbussen waren nicht eindeutig erkennbar. Die ermittelten Ertragsverluste erreichten bis 17%, entsprechend bis zu € 600,-/ha. In Feldexperimenten zur Erarbeitung von Lösungsstrategien wurden Aspekte zur Sortenanfälligkeit und Saatzeit untersucht, sowie Fragen zur Rolle der Gierschblattlaus Cavariella aegopodii als vermuteten Virusvektor. Verarbeitungsmöhren hatten gegenüber Frischmarktsorten eine überwiegend höhere Symptomanfälligkeit, während Fragen zu kritischen Saatterminen und der Phänologie des Vektorfluges aufgrund der Witterungsextreme in 2003 nicht abschliessend geklärt werden konnten und der weiteren Untersuchung bedürfen

Influence of planting date on incidence and severity of viral disease on cucurbits under field condition

Three field experiments were conducted to assess the effect of planting date on the incidence of viral diseases and the severity and the susceptibility of the cultivars. Two cultivars of cucumber (Hybrid Tokyo F1 and Poinsett) and one local variety of zucchini (Bolle) were used for the evaluation in May-July 2014, September-November 2014, and February-April 2015. A randomized complete block design with three replications was used for the experiments. Data were collected on disease incidence, severity, and time until first symptoms occurred. Area under severity index progress curve (AUSIPC) and area under disease progress curve (AUDPC) were calculated respectively for disease severity as well as the incidence on each cultivar. The results demonstrate the susceptibility of all cultivars to the tested viral diseases. The effect of planting dates on cultivars was significantly different (P  0.05) in planting date-variety interaction