Cereal and grass viruses
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How viruses hitch a ride on pollen to infect plants

How viruses hitch a ride on pollen to infect plants | Cereal and grass viruses | Scoop.it

Pollination is an essential step in the reproduction of flowering plants and is also crucial in agriculture in regard to fruit development, seed output, and the creation of new varieties of plants. However, at least 18 viruses can infect the mother plant through the fertilized flower (horizontal transmission by pollen). Horizontal transmission by pollen is epidemiologically important for viruses infecting perennial crops, since pollen grains from infected trees continue to be scattered every year. The mechanism how pollination with virus-infected pollen grains causes systemic viral infection to healthy plants has been unknown since the first report of horizontal transmission by pollen in 1918.

 


Via Ed Rybicki
Rabenstein, Frank's insight:

Would be also interesting to analyze mechanisms of the horizontal transmission by pollen of grass infecting viruses like Ryegrass cryptic virus.

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Variations in coat protein sequence of Wheat streak mosaic virus among crop and non-crop hosts

Variations in coat protein sequence of Wheat streak mosaic virus among crop and non-crop hosts | Cereal and grass viruses | Scoop.it

Khushwant Singh and Jiban Kumar Kundu (2017) Variations in coat protein sequence of Wheat streak mosaic virus among crop and non-crop hosts. Crop and Pasture Science: Vol. 68, No. 4, pp. 328-336. https://doi.org/10.1071/CP17025


Abstract. Wheat streak mosaic virus (WSMV) has become a re-emerging pathogen in recent years in the Czech Republic. Crop (e.g. wheat, barley, maize) and non-crop grasses from the Poaceae family are the natural hosts of the virus. Here, we report the results from coat protein (CP) gene-sequence analysis of WSMV isolates from wheat crops (four cultivars: Turondot, Bodyček, Avenue, Hymack) and three grass species (Agropyron repens, Phleum pratense, Poa pratensis). Phylogenetic reconstruction of putative CP sequences showed that all tested isolates clustered with existing type B isolates of WSMV (originating from Europe and Asia) rather than type D (originating from USA, Argentina, Australia, and Iran) and type A (originating from Mexico) isolates. Analysis of recombination events showed that Turondot and Hymack isolates recombined with P. pratense, whereas Bodyček and Avenue isolates recombined with a type B isolate (Iran_Saadat-Shahr). The grasses A. repens, P. pratense and P. pratensis share recombination events with type A (Mexico_El Batán), type B (French and German isolates) and type D (Iran_Naghadeh) isolates. The characteristic GCA (Gly276) triplet codon found in type B isolates was conserved in both the wheat and grass isolates. Notably, nucleotide variations were mainly observed at positions nt 381–389, nt 405–460 and nt 486–497 between crop and non-crop hosts. Based on our analysis, we propose that the grass isolates form subtype B1 within the type B isolates of WSMV. Putative CP amino acid sequences in the centre of the protein and in the C-terminal domain (aa 112–260) were significantly more frequently conserved in both wheat and grasses than those in the N-terminal domain (aa 11–80). Collectively, these results indicate that variations exist between crop and non-crop hosts of WSMV.



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Wheat streak mosaic virus coat protein is a determinant for vector transmission by the wheat curl mite

Highlights
 • WSMV CP was identified as a determinant for wheat curl mite transmission.
 • WSMV CP amino acids 58–100 are required for wheat curl mite transmission.
 • Amino acids 6–27, 36–57, and C-terminal 14 amino acids are dispensable for WSMV transmission by wheat curl mites.
 • Aspartic acid residues at positions 289 and 326 are required for efficient WSMV transmission by wheat curl mites.

Abstract
Wheat streak mosaic virus (WSMV; genus Tritimovirus; family Potyviridae), is transmitted by the wheat curl mite (Aceria tosichella Keifer). The requirement of coat protein (CP) for WSMV transmission by the wheat curl mite was examined using a series of viable deletion and point mutations. Mite transmission of WSMV was completely abolished with deletions comprising CP amino acids 58–100. In contrast, the amino-proximal (amino acids 6–27 and 36–57) and carboxy-terminal (14 amino acids) regions of CP were expendable for mite transmission. Mutation of aspartic acid residues at amino acid positions 289 or 326 (D289A or D326A) at the carboxy-proximal region of CP significantly reduced mite transmission. Remarkably, every wheat plant infected by mutants D289A or D326A through mite transmission but not with in vitro transcripts contained a second-site mutation of R131C and N275H, respectively. Collectively, these data demonstrate for the first time that CP is a determinant for an eriophyid-transmitted plant virus.
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Frontiers | Identification, Characterization and Full-Length Sequence Analysis of a Novel Polerovirus Associated with Wheat Leaf Yellowing Disease | Microbiology

Frontiers | Identification, Characterization and Full-Length Sequence Analysis of a Novel Polerovirus Associated with Wheat Leaf Yellowing Disease | Microbiology | Cereal and grass viruses | Scoop.it
To identify the pathogens responsible for leaf yellowing symptoms on wheat samples collected from Jinan, China, we tested for the presence of three known barley/wheat yellow dwarf viruses (BYDV-GAV, -PAV, WYDV-GPV) (most likely pathogens) using RT-PCR. A sample that tested negative for the three viruses was selected for small RNA sequencing. Twenty-five million sequences were generated, among which 5% were of viral origin. A novel polerovirus was discovered and temporarily named wheat leaf yellowing-associated virus (WLYaV). The full genome of WLYaV corresponds to 5 772 nucleotides (nt), with six AUG-initiated open reading frames, one non-AUG-initiated open reading frame and three untranslated regions, showing typical features of the family Luteoviridae. Sequence comparison and phylogenetic analyses suggested that WLYaV had the closest relationship with sugarcane yellow leaf virus (ScYLV), but the identities of full genomic nucleotides and deduced amino acid sequence of coat protein (CP) were 64.9% and 86.2%, respectively, below the species demarcation thresholds (90%) in the family Luteoviridae. Furthermore, agroinoculation of Nicotiana benthamiana leaves with a cDNA clone of WLYaV caused yellowing symptoms on the plant. Our study adds a new polerovirus that is associated with wheat leaf yellowing disease, which would help to identify and control pathogens of wheat.
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Impact of endophytic entomopathogenic fungus on plant attractivity in aphid-virus-plant interactions - Fingu Mabola Junior Corneille

Endophytic entomopathogenic fungi (EEPF) are biological control agents able to live in their host plants in a symbiotic interaction and secrete secondary metabolites in the host plant tissues interacting with pests and phytopathogenic agents like plants virus. This is the case of Barley yellow dwarf virus (BYDV) transmitted by the Bird cherry oat aphid (Rhopalosiphum padi Linnaeus) and the Grain aphid (Sitobion avenae Fabricius). This virus is one of the most economically important phytoviruses affecting major world cereal crops such as wheat, rice and corn, causing significant yield losses. In this study, we investigated the influence of EEPF presence in the plant tissues on the vector’s orientation preference by considering the insect virus-infection status. We performed a choice test in Petri dishes and collection of volatile compounds emitted by plants. The impact of these interactions between plant-fungi-virus is finally discussed.
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Molecular characterization of the mild Soil-borne wheat mosaic virus-Pol1 isolate

Molecular characterization of the mild Soil-borne wheat mosaic virus-Pol1 isolate | Cereal and grass viruses | Scoop.it

Soil-borne wheat mosaic virus is the causal agent of leaf mosaic symptoms in cereals. The low virulence and limited propagation in infected plant tissues of a Polish isolate (SBWMV-Pol1) differ from the characteristics of other known isolates. The research aimed to clarify the effects of nucleotide sequence variability on the observed biological differences among the following three isolates: SBWMV-Pol1, SBWMV-Heddesheim and SBWMV-SH1-3. Because of insufficient information regarding reference isolates, the RNAs from German isolates were sequenced for subsequent comparative analyses. Partial RNA1 and nearly complete RNA2 sequence for the Polish and two German isolates were obtained. Comparative analysis of received sequences with those of the corresponding fragments from other SBWMV isolates deposited in the GenBank database was carried out. The results of examined isolates confirmed: complete amino acid and nucleotide sequence identities for the replicase (REP) fragment 2 and the cysteine-rich protein, as well as complete amino acid and partial nucleotide sequence identities for the REP fragment 1 (99.4–100%) and the coat protein (87 − 100%), respectively. Differences in the amino acid and nucleotide sequences of the movement protein (MP) (98.7–99.6% and 99.5% sequence identities, respectively) were also detected. The sequence of the -Pol1 isolate was very similar to those of the -SH1-3 and -Heddesheim isolates, with only one and three non-synonymous point mutations in the MP gene, respectively. Nevertheless, there were obvious differences in the biological properties of these isolates. Point mutations within the MP gene may have considerable consequences for symptom development.

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Co-infection with a wheat rhabdovirus causes a reduction in Mal de Río Cuarto virus titer in its planthopper vector | Bulletin of Entomological Research | Cambridge Core

A.D. Dumón, E.B. Argüello Caro, M.F. Mattio, V. Alemandri, M. del Vas, G. Truol


Abstract

Mal de Río Cuarto virus (MRCV, Fijivirus, Reoviridae) causes one of the most important diseases in maize (Zea mays L.) in Argentina and has been detected in mixed infections with a rhabdovirus closely related to Maize yellow striate virus. In nature both viruses are able to infect maize and several grasses including wheat, and are transmitted in a persistent propagative manner by Delphacodes kuscheli Fennah (Hemiptera: Delphacidae). This work describes the interactions between MRCV and rhabdovirus within their natural vector and the consequences of such co-infection regarding virus transmission and symptom expression. First- and third-instar D. kuscheli nymphs were fed on MRCV-infected wheat plants or MRCV-rhabdovirus-infected oat plants, and two latency periods were considered. Transmission efficiency and viral load of MRCV-transmitting and non-transmitting planthoppers were determined by real-time quantitative polymerase chain reaction analysis (RTqPCR). Vector transmission efficiency was related to treatments (life stages at acquisition and latency periods). Nevertheless, no correlation between transmission efficiency and type of inoculum used to infect insects with MRCV was found. Treatment by third-instar nymphs 17 days after Acquisition Access Period was the most efficient for MRCV transmission, regardless of the type of inoculum. Plants co-infected with MRCV and rhabdovirus showed the typical MRCV symptoms earlier than plants singly infected with MRCV. The transmitting planthoppers showed significantly higher MRCV titers than non-transmitting insects fed on single or mixed inocula, confirming that successful MRCV transmission is positively associated with viral accumulation in the insect. Furthermore, MRCV viral titers were higher in transmitting planthoppers that acquired this virus from a single inoculum than in those that acquired the virus from a mixed inoculum, indicating that the presence of the rhabdovirus somehow impaired MRCV replication and/or acquisition. This is the first study about interactions between MRCV and a rhabdovirus closely related to Maize yellow striate virus in this insect vector (D. kuscheli), and contributes to a better understanding of planthopper–virus interactions and their epidemiological implications.

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Epidemic of yellow dwarf virus diseases in cereal growing areas and their control Yellow dwarf virus

 (YDVs) diseases are one of the most important diseases which have reduced crop yield and quality in the cereal growing areas by causing epidemics from time to time on all over the world as well as in Turkey. Just as prevailing in some potential cereal producer provinces of Turkey as well as in Edirne, Kırklareli and Tekirdağ provinces of Trakya Region during the year of 2016, yellow dwarf virus epidemic diseases were taken place. Those virus diseases in cereal fields have become widespread especially in wheat fields which have reduced the yield and quality and caused economic losses. Survey studies were conducted and observation on YDVs disease epidemics in cereal fields especially in Edirne, Kırklareli and Tekirdağ provinces. At least 187 plant leaf samples were collected from the symptomatic winter bread wheat, barley and oat plants exhibiting yellowing, dwarfing, reddish symptoms and signs in the cereal growing areas. So, beside 138 bread wheat (Triticum aestivum L.), 19 barley (Hordeum vulgare L.) and 10 oat (Avena sativa L.) leaf samples, 20 samples were obtained from the perennial Poaceae weed host common reed (Phragmites austrialis (Cav.) Trin ex. Steudel). Barley yellow dwarf virus-PAV (BYDV- PAV), Barley yellow dwarf virus-MAV (BYDV-MAV) and Cereal yellow dwarf virus-RPV (CYDV-RPV) from YDVs were searched by employing double antibody sandwich enzyme linked immunosorbent assay (DAS-ELISA) test. Reverse transcription polymerase chain reaction (RT-PCR) test was implemented for suspected leaf samples. As a result of DAS- ELISA and RT-PCR tests, 89 out of 187 leaf samples at the rate of 47.59% were found infected with BYDV-PAV. As 30 samples at the rate of 16.04% had CYDV-RPV and 4 of 187 leaf samples at rate of 2.14% were infected with BYDV-MAV viruses individually. Merely 14 out of 187 leaf samples at the rate of 48% were found infected with these tested YDVs (BYDV-PAV, BYDV-MAV and CYDV-RPV) as mixed infections. During the year of 2016, YDVs infections were determined at the highest level of incidence rate being 36.89% in the cereal growing areas of Edirne province. As in Kırklareli, YDVs incidence
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CiNii Article - Breeding of a New Soft Wheat Cultivar "Fukuakari" with Pre-harvest Sprouting Resistance


Breeding of a New Soft Wheat Cultivar "Fukuakari" with Pre-harvest Sprouting Resistance 小田 俊介 , 乙部(桐淵) 千雅子 , 関 昌子 , 小島 久代 , 松中 仁 , 藤田 雅也 , 吉岡 藤治 , 柳沢 貴司 , 吉田 久 農研機構研究報告 次世代作物開発研究センター = Bulletin of the NARO, Crop Science (1), 15-32, 2017-07-31

"Fukuakari" was registered as a new wheat cultivar in 2010. It was bred by the bulk methodat the NARO Institute of Crop Science, Tsukuba, Ibaraki, Japan, from a cross made in 1998between "Tanikei RA4215" and "Kanto 119"."Fukuakari" is an awned, brown-glumed, soft wheat cultivar with red seeds. The degree ofits winter habit is I–II( spring type). Compared with "Norin 61", the leading cultivar in centraland southwestern Japan, "Fukuakari" has shorter culm length and superior lodging resistance."Fukuakari" matures 4 days earlier and its yield is higher than that of "Norin 61". "Fukuakari" isresistant to wheat yellow mosaic virus and powdery mildew but susceptible to scab. "Fukuakari"shows good noodle texture because its amylose content is lower than that of "Norin 61".Fukushima prefecture designated "Fukuakari" as a recommended cultivar in 2011,

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Improved gross margin generated by the use of the new barley variety "Imen" selected for its resistance to Barley yellow dwarf virus (BYDV)

Improved gross margin generated by the use of the new barley variety "Imen" selected for its resistance to Barley yellow dwarf virus (BYDV) | Cereal and grass viruses | Scoop.it
Barley is the second widely cultivated cereal crop in Tunisia. It covers around 500 000 ha/year. The national mean yield is estimated to 14qx/ha. However, recent studies in Tunisia have shown that Barley yellow dwarf virus (BYDV) is the most important virus on barley. In fact, the contamination can exceed, in some areas 35% in barley crops. The selection of resistant genotypes is the most effective method against BYDV. A screening program for resistance to BYDV was initiated during these last few years. Selected barley resistant advanced lines were assessed for agronomic related traits under semi-arid climatic conditions from 2007 to 2013 growing seasons using Manel and Rihane the most commonly grown barley varieties in Tunisia (checks). Within these lines, a new resistant variety “Imen” carrying Yd2 gene was released because of its high yield and biomass. Imen is well adapted to semi-arid areas. The superiority of Imen was significantly estimated (Fpr
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Importance of BYDV on barley and oat in Tunisia and evaluation of viral infection on their forage quality

Importance of BYDV on barley and oat in Tunisia and evaluation of viral infection on their forage quality | Cereal and grass viruses | Scoop.it
Cereals are considered as strategic crops in Tunisia because of their economic and social relevance and the importance of the cultivated areas. Viral diseases and particularly barley yellow dwarf virus (BYDV) represent one of the major constraints that reduce the genetic potential of most cereal species and cultivars. In this context our study aims to assess the prevalence and the geographical distribution of BYDV and to evaluate the virus incidence on biomass and forage quality on oat and barley that provide important part of forage production for ruminants in Tunisia. In this regard, a field survey was conducted during 2015/2016 growing season in North-Eastern regions (Bizerte,CapBon, Mateur) and North-Western region (Kef, Fahs) and Central-Eastern region (Kairouan).For barley, Tissue blot immunoassays (TBIA) results showed that BYDV were most common in Fahs, Mateur and Bizerte with detectable incidence rate is nearly of 40% in randomly collected samples from these three locations. For oat, BYDV infection was more important in Mateur (35%), followed by Bizerte and Cap Bon regions who have a similar infection (23%).Among the different BYDVs identified, BYDV-PAV was the most common compare to CYDV-RPV with 18 % for barley and 57% for oat. Based on BYDV inoculation, significant biomass decreases were recorded for barley and reached 48% and 50% respectively for Manel and Rihane followed by the Meliane oat variety (42%). These results confirm the sensitivity of these varieties to the virus. The chemical composition of the different samples of barley and oat analyzed shows that only the lignin (ADL) levels show a significant difference between the two varieties into the two species. In fact, Rihane is more rich than Manel by 80%. The same trend was observed for Bizanta, which exceeds Meliane by 58%.
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Epidemiology of barley yellow dwarf and wheat dwarf diseases

Epidemiology of barley yellow dwarf and wheat dwarf diseases | Cereal and grass viruses | Scoop.it
The most important cereal viruses are Barley/Cereal yellow dwarf virus (B/CYDV, genera Luteovirus/Polerovirus, family Luteoviridae) and Wheat dwarf virus (WDV, genus Mastrevirus, family Geminiviridae). B/CYDV is a complex of at least nine viral species and WDV consists of two main strains. B/CYDV and WDV are exclusively transmitted by aphids and leafhoppers, respectively. In spite of a wealth of data on both B/CYDV and WDV pathosystems, little information is available processes related to (i) the emergence, spread and maintenance of these viruses in a landscape including cultivated and wild compartments and (ii) the interactions between these viral species and between their vectors. An intensive survey was conducted to collect plants and insects in a 5 km² landscape (Annoix, Cher, France) where B/CYDV and WDV, and their vectors (i.e. cereal aphids and Psammotettix alienus), are usually highly prevalent. Previously characterized and putative host species of the Poaceae family present in the visited areas were sampled. Simultaneously, aphids and leafhoppers were caught using yellow water traps and sticky traps. The presence of BYDV-PAV, BYDV-MAV, CYDV-RPV and WDV in collected plants and insects was assessed using serological and molecular tools. A total of 37 wild gramineous species were identified. Serological analyses revealed that B/CYDV was present in 9 wild gramineous species.
Surprisingly, none of the thousands collected leaves were infected by WDV. To complement the description of the gramineous species present in the studied landscape and their possible role as viral reservoirs (Abt et al., 2017), interactions between viruses and between vectors with overlapping host ranges will be analyzed in order to determine (i) how these pathogens (and their vectors) compete for host resources and (ii) the consequences of such interactions on the epidemiology of barley yellow dwarf and wheat dwarf diseases.
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Imact of timing and method of virus inoculation on the severity of wheat streak mosaic disease

Wheat streak mosaic virus (WSMV), transmitted by the wheat curl mite Aceria tosichella, frequently causes significant yield loss in winter wheat throughout the Great Plains of the United States. A field study was conducted in the 2013-14 and 2014-15 growing seasons to compare the impact of timing of WSMV inoculation (early fall, late fall or early spring) and method of inoculation (mite or mechanical) on susceptibility of winter wheat cultivars ‘Mace’ (resistant) and ‘Overland’ (susceptible). Relative chlorophyll content, WSMV incidence, and yield components were determined. The greatest WSMV infection occurred for ‘Overland’, with the early fall inoculations resulting in the highest WSMV infection rate (up to 97%) and the greatest yield reductions relative to the control (up to 94%). In contrast, inoculation of ‘Mace’ resulted in low WSMV incidence (1-28.3%). The findings from this study indicate that both method of inoculation and wheat cultivar influenced severity of wheat streak mosaic; however, timing of inoculation also had a dramatic influence on disease. In addition, mite inoculation provided much more consistent infection rates and is considered a more realistic method of inoculation to measure disease impact on wheat cultivars.
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Biophysical analysis of BMV virions purified using a novel method

Highlights

• We present a novel purification procedure for BMV.
• We confirm high stability of the BMV capsid in pH range from 5.6 to 8.4.
• We present results of secondary structure analysis of BMV capsid protein.

Abstract Brome mosaic virus (BMV) has been successfully loaded with different types of nanoparticles. However, studies concerning its application as a nanoparticle carrier demand high-purity virions in large amounts. Existing BMV purification protocols rely on multiple differential ultracentrifugation runs of the initially purified viral preparation. Herein, we describe an alternative method for BMV purification based on ion-exchange chromatography and size-exclusion chromatography (SEC) yielding 0.2 mg of virus from 1 g of plant tissue. Our method is of similar efficiency to previously described protocols and can easily be scaled up. The method results in high-quality BMV preparations as confirmed by biophysical analyses, including cryogenic transmission electron microscopy (cryo-TEM), dynamic light scattering (DLS), static light scattering (SLS), and circular dichroism (CD) measurements and attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) spectroscopy. Our results revealed that purified BMV capsids are stable and monodisperse and can be used for further downstream applications. In this work, we also characterize secondary structure and size fluctuations of the BMV virion at different pH values.
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Relationships Between Early Wheat Streak Mosaic Severity Levels and Grain Yield: Implications for Management Decisions

Wheat streak mosaic (WSM) caused by Wheat streak mosaic virus, which is transmitted by the wheat curl mite (Aceria tosichella), is a major yield-limiting disease in the Texas High Plains. In addition to its impact on grain production, the disease reduces water-use efficiency by affecting root development. Because of the declining Ogallala Aquifer water level, water conservation has become one of the major pressing issues in the region. Thus, questions are often raised as to whether it is worthwhile to irrigate infected fields in light of the water conservation issues, associated energy costs, and current wheat prices. To address some of these questions, field experiments were conducted in 2013 and 2016 at two separate locations to determine whether grain yield could be predicted from disease severity levels, assessed early in the spring, for potential use as a decision tool for crop management, including irrigation. In both fields, disease severity assessments started in April, using a handheld hyperspectral radiometer with which reflectance measurements were taken weekly in multiple plots in arbitrarily selected locations across the fields. The relationship between WSM severity levels and grain yield for the different assessment dates were determined by fitting reflectance and yield values into the logistic regression function. The model predicted yield levels with r2 values ranging from 0.67 to 0.85 (P < 0.0001), indicating that the impact of WSM on grain yield could be fairly well predicted from early assessments of WSM severity levels. As the disease is normally progressive over time, this type of information will be useful for making management decisions of whether to continue irrigating infected fields, especially if combined with an economic threshold for WSM severity levels.
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ICTV Online (10th) Report (2017)

ICTV Online (10th) Report (2017) | Cereal and grass viruses | Scoop.it
Virus Taxonomy: The Classification and Nomenclature of Viruses
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The first population of the small brown planthopper Laodelphax striatellus (Homoptera: Delphacidae) in the Netherlands

The small brown planthopper Laodelphax striatellus has always been considered a migrant species in the Netherlands, since no established populations were known. However, the first reproducing Dutch population was discovered in 2016. Climate change might have caused an area extension of L. striatellus. Future research has to show whether the area extension is permanent. Unfortunately, the habitat of the discovered population is destroyed. The small brown planthopper is of economic importance in southern Europe, mainly due to transmission of the maize rough dwarf virus (MRDV). In this respect, attention should be given to possible area extensions of this species.
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Frontiers | Differential Characteristics of Viral siRNAs between Leaves and Roots of Wheat Plants Naturally Infected with Wheat Yellow Mosaic Virus, a Soil-Borne Virus | Microbiology

Frontiers | Differential Characteristics of Viral siRNAs between Leaves and Roots of Wheat Plants Naturally Infected with Wheat Yellow Mosaic Virus, a Soil-Borne Virus | Microbiology | Cereal and grass viruses | Scoop.it
RNA silencing is an important innate antiviral defense in plants. Soil-borne plant viruses naturally infect roots via soil-inhabiting vectors, but it is unclear how antiviral RNA silencing responds to virus infection in this particular tissue. In this study, viral small interfering RNA (siRNA) profiles from leaves and roots of wheat plants naturally infected with a soil-borne virus, Wheat yellow mosaic virus (WYMV, genus Bymovirus), were analyzed by deep sequencing. WYMV siRNAs were much more abundant in roots than leaves, which was positively correlated with the accumulation of viral RNA. WYMV siRNAs in leaves and roots were predominantly 21- and 22-nt long and equally derived from the positive- and negative-strands of the viral genome. WYMV siRNAs from leaves and roots differed in distribution pattern along the viral genome. Interestingly, compared to siRNAs from leaves (and most other reports), those from roots obviously had a lower A/U bias at the 5-terminal nucleotide. Moreover, the expression of dicer-like genes upon WYMV infection were differently regulated between leaves and roots. Our data suggest that RNA silencing in roots may operate differently than in leaves against soil-borne virus invasion.
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EFFECT OF SOWING DATE ON OCCURRENCE AND SEVERITY OF BARLEY YELLOW DWARF VIRUS (BYDV) IN DIFFERENT WHEAT CULTIVARS

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Search Results - virus in Wheat Biotechnology Methods and Protocols

Wheat Biotechnology Methods and Protocols
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Sequencing flow-sorted short arm of Haynaldia villosa chromosome 4V provides insights into its molecular structure and virtual gene order

Sequencing flow-sorted short arm of Haynaldia villosa chromosome 4V provides insights into its molecular structure and virtual gene order | Cereal and grass viruses | Scoop.it

Haynaldia villosa (H. villosa) has been recognized as a species potentially useful for wheat improvement. The availability of its genomic sequences will boost its research and application. In this work, the short arm of H. villosa chromosome 4V (4VS) was sorted by flow cytometry and sequenced using Illumina platform. About 170.6 Mb assembled sequences were obtained. Further analysis showed that repetitive elements accounted for about 64.6% of 4VS, while the coding fraction, which is corresponding to 1977 annotated genes, represented 1.5% of the arm. The syntenic regions of the 4VS were searched and identified on wheat group 4 chromosomes 4AL, 4BS, 4DS, Brachypodium chromosomes 1 and 4, rice chromosomes 3 and 11, and sorghum chromosomes 1, 5 and 8. Based on genome-zipper analysis, a virtual gene order comprising 735 gene loci on 4VS genome was built by referring to the Brachypodium genome, which was relatively consistent with the scaffold order determined for Ae. tauschii chromosome 4D. The homologous alleles of several cloned genes on wheat group 4 chromosomes including Rht-1 gene were identified. The sequences provided valuable information for mapping and positional-cloning genes located on 4VS, such as the wheat yellow mosaic virus resistance gene Wss1. The work on 4VS provided detailed insights into the genome of H. villosa, and may also serve as a model for sequencing the remaining parts of H. villosa genome.
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Potyvirus virion structure shows conserved protein fold and RNA binding site in ssRNA viruses

Potyvirus virion structure shows conserved protein fold and RNA binding site in ssRNA viruses | Cereal and grass viruses | Scoop.it
Potyviruses constitute the second largest genus of plant viruses and cause important economic losses in a large variety of crops; however, the atomic structure of their particles remains unknown. Infective potyvirus virions are long flexuous filaments where coat protein (CP) subunits assemble in helical mode bound to a monopartite positive-sense single-stranded RNA [(+)ssRNA] genome. We present the cryo-electron microscopy (cryoEM) structure of the potyvirus watermelon mosaic virus at a resolution of 4.0 Å. The atomic model shows a conserved fold for the CPs of flexible filamentous plant viruses, including a universally conserved RNA binding pocket, which is a potential target for antiviral compounds. This conserved fold of the CP is widely distributed in eukaryotic viruses and is also shared by nucleoproteins of enveloped viruses with segmented (−)ssRNA (negative-sense ssRNA) genomes, including influenza viruses.
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Complete genome sequence of maize yellow striate virus, a new cytorhabdovirus infecting maize and wheat crops in Argentina

Complete genome sequence of maize yellow striate virus, a new cytorhabdovirus infecting maize and wheat crops in Argentina | Cereal and grass viruses | Scoop.it

A rhabdovirus infecting maize and wheat crops in Argentina was molecularly characterized. Through next-generation sequencing (NGS) of symptomatic leaf samples, the complete genome was obtained of two isolates of maize yellow striate virus (MYSV), a putative new rhabdovirus, differing by only 0.4% at the nucleotide level. The MYSV genome consists of 12,654 nucleotides for maize and wheat virus isolates, and shares 71% nucleotide sequence identity with the complete genome of barley yellow striate mosaic virus (BYSMV, NC028244). Ten open reading frames (ORFs) were predicted in the MYSV genome from the antigenomic strand and were compared with their BYSMV counterparts. The highest amino acid sequence identity of the MYSV and BYSMV proteins was 80% between the L proteins, and the lowest was 37% between the proteins 4. Phylogenetic analysis suggested that the MYSV isolates are new members of the genus Cytorhabdovirus, family Rhabdoviridae. Yellow striate, affecting maize and wheat crops in Argentina, is an emergent disease that presents a potential economic risk for these widely distributed crops.

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Integrating multiple criteria for the characterization of Psammotettix populations in European cereal fields | Bulletin of Entomological Research | Cambridge Core

The wheat dwarf disease is among the most damaging diseases in cereals. Its aetiological agent is the Wheat dwarf virus (WDV), which is exclusively transmitted from plant to plant by leafhoppers from the genus Psammotettix (Hemiptera, Cicadellidae). The parameters linked to the WDV/Psammotettix pathosystem are still poorly understood. We studied Psammotettix individuals collected in wheat and barley fields in France and, as a comparison, from grassland at agroecological interface in West Slovenia. Species identity of males and females has been determined using multiple criteria. In the first step, the characterization of the collected individuals included recordings of vibrational signals used in mating behaviour and morphometric analyses. In addition, a 442 nt sequence of the mitochondrial cytochrome oxydase I (COI) gene was obtained for some individuals and compared to COI sequences of the Psammotettix leafhoppers available in public databases. In the cereal fields in France, P sammotettix alienus was the most numerous species; however, it sometimes occurred together with Psammotettix confinis, while in the grasslands in Slovenia, the third syntopic species in Psammotettix community was Psammotettix helvolus. The temporal parameters of the P. alienus male calling song that were measured in this study were very similar to those measured in a previous study. The local biotic and/or abiotic parameters most likely influence the life history of Psammotettix leafhoppers, and the proportion of viruliferous individuals collected in cereal fields was 14.9%, while leafhoppers collected in Slovenia were virus-free. Taken together, results show that more detailed information on population structure of Psammotettix leafhoppers is crucial for providing an insight into the epidemiology of wheat dwarf disease.

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Psammotettix alienus-mediated inoculations of barley and wheat strains of Wheat dwarf virus to wild gramineous species

Psammotettix alienus-mediated inoculations of barley and wheat strains of Wheat dwarf virus to wild gramineous species | Cereal and grass viruses | Scoop.it
Wheat dwarf virus (WDV, family Geminiviridae, genus Mastrevirus) is the causal agent of dwarfing, mottling and yellowing symptoms in wheat and barley. WDV is exclusively transmitted by leafhoppers from the genus Psammotettix in a persistent manner and infects plants of the Poaceae family. Phylogenetic analyses carried out with WDV genomic sequences showed that this viral species comprises several strains including the originally described wheat (WDV-w) and barley (WDV-b) strains. Psammotettix leafhoppers collected in different French cereal-growing areas were characterized using recordings of vibrational signals used during mating, morphometric
analyses and sequences of the COI gene. Characterized P. alienus individuals were used as WDV vectors to assess the host ranges of isolates from the WDV-w and WDV-b strains. Thirty-seven wild gramineous species were identified in a 5-km² cereal-growing area located in Annoix (Cher, France) where WDV and Psammotettix leafhoppers are usually highly prevalent (Gauthier et al., 2017). Whenever seeds were available, susceptibility of wild gramineous species to WDV was tested using P. alienus-mediated WDV inoculations. The characterization of field-collected Psammotettix showed that P. alienus is the prevalent Psammotettix species and sometimes it is found syntopically with P. confinis. Leafhopper mediated transmission experiments highlighted that (i) the two WDV strains have different but slightly overlapping host ranges, (ii) three gramineous species not yet reported to be WDV hosts (i.e. Alopecurus myosuroides, Cynosurus cristatus and Poa annua) could be infected by WDV, and (iii) Setaria viridis, described in the literature as non-host for WDV, was successfully infected by the WDV-w isolate.
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Virus Diseases of Cereals - eLS - Rakotondrafara - Wiley Online Library

Virus Diseases of Cereals - eLS - Rakotondrafara - Wiley Online Library | Cereal and grass viruses | Scoop.it
Abstract
A serious constraint to agricultural productivity and a constant pressure to global food security and hunger are infections of plants with viruses. Of particular concern is the impact of viruses and their vectors on cereals, wheat, maize (corn in the USA), rice, barley, sorghum, oats, millet and rye, which provide much of the world's food and drink. Because viral populations evolve quickly, the emergence of new variants of classic viruses with stronger virulence, the occurrence of viruses switching host from the wild species to the cultivated crops, or recombinants between different families, pose a serious challenge in the control of viruses and to the durability of widely deployed resistance against viruses. As there are essentially no chemical options to prevent viral infections, genetic resistance remains the most sustainable strategy for combating these major agricultural pests.
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