40 research outputs found
Biological and genetic characterization of Physostegia chlorotic mottle virus in Europe based on host range, location, and time
No full textApplication of high throughput sequencing (HTS) technologies enabled the first identification of Physostegia chlorotic mottle virus (PhCMoV) in 2018 in Austria. Subsequently, PhCMoV was detected in Germany and Serbia on tomatoes showing severe fruit mottling and ripening anomalies. We report here how prepublication data-sharing resulted in an international collaboration across eight laboratories in five countries, enabling an in-depth characterization of PhCMoV. The independent studies converged toward its recent identification in eight additional European countries and confirmed its presence in samples collected 20 years ago (2002). The natural plant host range was expanded from two to nine species across seven families, and we confirmed the association of PhCMoV presence with severe fruit symptoms on economically important crops such as tomato, eggplant, and cucumber. Mechanical inoculations of selected isolates in the greenhouse established the causality of the symptoms on a new indexing host range. In addition, phylogenetic analysis showed a low genomic variation across the 29 near-complete genome sequences available. Furthermore, a strong selection pressure within a specific ecosystem was suggested by nearly identical sequences recovered from different host plants through time. Overall, this study describes the European distribution of PhCMoV on multiple plant hosts, including economically important crops on which the virus can cause severe fruit symptoms. This work demonstrates how to efficiently improve knowledge on an emergent pathogen by sharing HTS data and provides a solid knowledge foundation for further studies on plant rhabdoviruses
EOR Screening for the Rijn Oil Field by Numerical Simulation
No full textA screening study and subsequent dynamic simulation of selected Enhanced Oil Recovery (EOR) methods for the Rijn oil field are presented. The objective of the study was to obtain insight in the EOR potential of the Rijn field. The Rijn oil field, located in block P15 in the Dutch sector of the North Sea Continental Shelf, produced 24MMSTB oil cumulative (RF= 12-18%) by water flooding and gas lift from 1986 until 1998 and was re-developed in 2010, using electrical submersible pumps (ESP’s), expecting another 3.5MMSTB (expected RF= 21%). In general an EOR method has to address certain reservoir characteristics such as heterogeneity, remaining oil saturation and residual oil saturation. For the Rijn oil field the presence of a thief zone, extensive water cycling, the offshore location and a relatively short remaining field life were also important factors taken into account when making a selection. From the screening study polymer flooding, surfactant flooding and in-depth conformance control (by BrightWater\u99) were selected for investigation by numerical simulations. Other techniques such as solvent, microbial and thermally enhanced recovery methods were discarded based on the field characteristics. Numerical modelling was done on a detailed sector model of the Rijn field with a refined grid, instead of using a conceptual simulation model. This was done to incorporate realistic reservoir and geological conditions. Polymer flooding showed disappointing production responses mainly caused by injectivity issues due to increased viscosity of the injected fluid. In-depth conformance control using BrightWater\u99 did not increase recovery because the poor reservoir quality in the modelled reservoir sector. A simulation run, where the high permeable thief zone was blocked, displayed a decrease in water cut but also a decrease in oil production. It is expected that better results could be obtained when the method is applied to better quality parts of the reservoir. The EOR method with the best response was surfactant flooding. Adding surfactant to the injection water showed 12% increase in oil recovery. The results presented form a basis for further investigation of surfactant systems for applications in the Rijn oil field.Section Petroleum EngineeringCivil Engineering and Geoscience
First Expansion of the Public Tomato Brown Rugose Fruit Virus (ToBRFV) Nextstrain Build; Inclusion of New Genomic and Epidemiological Data
No full textTomato brown rugose fruit virus (ToBRFV) is a tobamovirus that was first detected in Israel and Jordan following an outbreak of a new disease infecting tomato in 2014. Since then, the virus has been reported from all continents except Oceania and Antarctica. In response to the first finding of the virus in The Netherlands, the Dutch National Plant Protection Organization created a ToBRFV Nextstrain build (v1). In this report, we announce 47 new (near) complete ToBRFV genomes and the generation of the new ToBRFV Nextstrain (v2) build containing 118 ToBRFV genomes with associated geographic and epidemiological data. Examples of utilization of the genomic sequences are presented, and we report the first sequence from South America and present a novel hypothesis on the possible ToBRFV center of origin.[Figure: see text] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license
Revision of the African genus Hexalobus (Annonaceae)
No full textThe genus Hexalobus consists of five species characterized by six basally fused petal lobes that are transversally folded in bud, which is unique within Annonaceae. The genus is widespread across tropical Africa occurring in rain forest, savanna, and woodland. The species H. callicarpus, occurring in Madagascar, is excluded from Hexalobus, so the genus is now restricted to continental Africa. The present revision provides a synthesis of previously published information and discussions on morphology, taxonomy, phylogeny, and palynology. Conservation status assessments are provided for each species, as well as a diagnostic key and detailed species descriptions. Furthermore, four species are illustrated and all species are mapped
African eggplant-associated virus: Characterization of a novel tobamovirus identified from Solanum macrocarpon and assessment of its potential impact on tomato and pepper crops.
No full textA novel tobamovirus was identified in a fruit of Solanum macrocarpon imported into the Netherlands in 2018. This virus was further characterized in terms of host range, pathotype and genomic properties, because many tobamoviruses have the potential to cause severe damage in important crops. In the original fruit, two different genotypes of the novel virus were present. The virus was able to infect multiple plant species from the Solanaceae family after mechanical inoculation, as well as a member of the Apiaceae family. These species included economically important crops such as tomato and pepper, as well as eggplant and petunia. Both tomato and pepper germplasm were shown to harbor resistance against the novel virus. Since most commercial tomato and pepper varieties grown in European greenhouses harbor these relevant resistances, the risk of infection and subsequent impact on these crops is likely to be low in Europe. Assessment of the potential threat to eggplant, petunia, and other susceptible species needs further work. In conclusion, this study provides a first assessment of the potential phytosanitary risks of a newly discovered tobamovirus, which was tentatively named African eggplant-associated virus
Possible Overestimation of Seed Transmission in the Spread of Pospiviroids in Commercial Pepper and Tomato Crops Based on Large-Scale Grow-Out Trials and Systematic Literature Review
No full textSeveral outbreaks of pospiviroids have been reported in pepper and tomato crops worldwide. Tracing back the origin of the infections has led to different sources. In some cases, the infections were considered to result from seed transmission. Other outbreaks were related to transmission from ornamental crops and weeds. Pospiviroids, in particular potato spindle tuber viroid, are regulated by many countries because they can be harmful to potatoes and tomatoes. Seed transmission has been considered an important pathway of introduction and spread. However, the importance of this pathway can be questioned. This paper presents data on seed transmission from large-scale grow-out trials of infested pepper and tomato seed lots produced under standard seed-industry conditions. In addition, it presents the results of a systematic review of published data on seed transmission and outbreaks in commercial pepper and tomato crops. Based on the results of the grow-out trials and review of the literature, it was concluded that the role of seed transmission in the spread of pospiviroids in practice is possibly overestimated
African eggplant-associated virus: Characterization of a novel tobamovirus identified from Solanum macrocarpon and assessment of its potential impact on tomato and pepper crops
No full textA novel tobamovirus was identified in a fruit of Solanum macrocarpon imported into the Netherlands in 2018. This virus was further characterized in terms of host range, pathotype and genomic properties, because many tobamoviruses have the potential to cause severe damage in important crops. In the original fruit, two different genotypes of the novel virus were present. The virus was able to infect multiple plant species from the Solanaceae family after mechanical inoculation, as well as a member of the Apiaceae family. These species included economically important crops such as tomato and pepper, as well as eggplant and petunia. Both tomato and pepper germplasm were shown to harbor resistance against the novel virus. Since most commercial tomato and pepper varieties grown in European greenhouses harbor these relevant resistances, the risk of infection and subsequent impact on these crops is likely to be low in Europe. Assessment of the potential threat to eggplant, petunia, and other susceptible species needs further work. In conclusion, this study provides a first assessment of the potential phytosanitary risks of a newly discovered tobamovirus, which was tentatively named African eggplant-associated virus
Pollen morphology within the Monodora clade, a diverse group of five African Annonaceae genera
No full textPollen morphology has played a major role in elucidating infrafamiliar-level systematics and evolution within Annonaceae, especially within the African genera. The Monodora clade is composed of five genera, Asteranthe, Hexalobus, Isolona, Monodora and Uvariastrum, which are restricted to Africa and contain together c. 50 species. A molecular phylogeny of the family showed that the monophyly of the Monodora clade is strongly supported and that it is part of a larger clade of 11 African genera. In order to support classification a detailed survey was made of the pollen morphological variation within the Monodora clade, using scanning and transmission electron microsopy. For the two most species-rich genera, Isolona and Monodora, a molecular species-level phylogeny was used to assess the taxonomic usefulness of the pollen characters. The survey showed a wide range of pollen morphological diversity. The most conspicuous variation concerned the occurrence of monads without a thicker outer foliation in the basal exine layer in Isolona in contrast to tetrads with a thicker outer foliation in Asteranthe, Hexalobus, Monodora and Uvariastrum. At the infrageneric level, Hexalobus, Isolona and Monodora showed the largest diversity, with various pollen types based on tectum morphology. Hexalobus is exceptional with three types within only five species. The pollen types defined in this study are hardly useful in characterizing major groups identified within both Isolona and Monodora, but they do illustrate relationships within smaller groups
Revisiting a pollen-transmitted ilarvirus previously associated with angular mosaic of grapevine
No full textSummary: We report the characterization of a novel tri-segmented RNA virus infecting Mercurialis annua, a common crop weed and model species in plant science. The virus, named “Mercurialis latent virus” (MeLaV) was first identified in a mixed infection with the recently described Mercurialis orthotospovirus 1 (MerV1) on symptomatic plants grown in glasshouses in Lausanne (Switzerland). Both viruses were found to be transmitted by Thrips tabaci, which presumably help the inoculation of infected pollen in the case of MeLaV. Complete genome sequencing of the latter revealed a typical ilarviral architecture and close phylogenetic relationship with members of the Ilarvirus subgroup 1. Surprisingly, a short portion of MeLaV replicase was found to be identical to the partial sequence of grapevine angular mosaic virus (GAMV) reported in Greece in the early 1990s. However, we have compiled data that challenge the involvement of GAMV in angular mosaic of grapevine, and we propose alternative causal agents for this disorder. In parallel, three highly-conserved MeLaV isolates were identified in symptomatic leaf samples in The Netherlands, including a herbarium sample collected in 1991. The virus was also traced in diverse RNA sequencing datasets from 2013 to 2020, corresponding to transcriptomic analyses of M. annua and other plant species from five European countries, as well as metaviromics analyses of bees in Belgium. Additional hosts are thus expected for MeLaV, yet we argue that infected pollen grains have likely contaminated several sequencing datasets and may have caused the initial characterization of MeLaV as GAMV
Symptomatology of indicator plants inoculated with the homogenate from the intercepted <i>S</i>. <i>macrocarpon</i> fruit.
No full textSymptomatology of indicator plants inoculated with the homogenate from the intercepted S. macrocarpon fruit.</p
