Dwarf Virus In Oats Research Articles

The RING-Finger Protein NbRFP1 Contributes to Regulating the Host Hypersensitive Response Induced by Oat Dwarf Virus RepA.

Our previous study identified that the RepA protein encoded by the oat dwarf virus (ODV) was responsible for inducing a strong hypersensitive response (HR) during the virus infection in non-host tobacco plants. However, little was known about the molecular mechanism of the RepA-elicited HR. Here, a RING-finger protein, which is described as NbRFP1 and is mainly located in the cytoplasm and nucleus in Nicotiana benthamiana cells, was confirmed to interact with RepA. In addition, the accumulation level of NbRFP1 in N. benthamiana leaves was enhanced by either ODV infection or by only RepA expression. The knockdown of NbRFP1 by a TRV-mediated virus-induced gene silencing markedly delayed the ODV or RepA-elicited HR. By contrast, the overexpression of NbRFP1 in N. benthamiana conferred enhanced resistance to ODV infection and promoted RepA-induced HR. Further mutation analysis showed that a RING-finger domain located in NbRFP1 plays important roles in modulating RepA-induced HR, as well as in mediating the interaction between NbRFP1 and RepA.

Oat dwarf virus

This datasheet on Oat dwarf virus covers Identity, Hosts/Species Affected, Further Information.

Identification of the wild and cultivated hosts of wheat dwarf virus and oat dwarf virus in Iran.

In the last decade two mastreviruses, Wheat dwarf virus (WDV) and Oat dwarf virus (ODV) have been reported from cereal farms in Iran. In a survey, wild and cultivated hosts of these mastreviruses were studied during 2015 to 2017. Symptomatic small grain cereal samples and weed species were collected and assayed for WDV and/or ODV infection by PCR. While WDV which was detected in 139/284 (49%) of total symptomatic samples, low incidence (2%) was recorded for ODV which was detected only in slender wild oat (Avena barbata Pott ex Link) and red brome (Bromus rubens L.). In agroinfection studies, the clone of ODV infected common oat (A. sativa) and slender wild oat (A. barbata) with the low efficiency and did not infect wheat or barley. ODV was transmitted by the leafhopper Psammotettix alienus, from agroinfected common oat to healthy seedlings. The results show that, in contrast to WDV, ODV has a low incidence and a narrow host range in gramineous plants.

Gene Expression Profiling Shows That NbFDN1 Is Involved in Modulating the Hypersensitive Response-Like Cell Death Induced by the Oat dwarf virus RepA Protein

In this study, we used high-throughput deep nucleotide sequencing to characterize the global transcriptional response of Nicotiana benthamiana plants to transient expression of the RepA protein from Oat dwarf virus (ODV). We identified 7,878 significantly differentially expressed genes (DEG) that mapped to 125 pathways, suggesting that comprehensive networks are involved in regulation of RepA-induced cell death. Of the 202 DEG associated with photosynthesis, expression of 195 was found to be downregulated, indicating a significant inhibition of photosynthesis in response to RepA expression, which is associated with chloroplast disruption and physiological changes. We focused our analysis on NbFDN1, a member of the ferredoxin protein family that participates in the chloroplast electron transport chain performing oxygenic photosynthesis, which was identified to directly interact with NbTsip1. We separately knocked down the expression of NbFDN1 and NbTsip1 using virus-induced gene silencing, and found that NbFDN1 silencing speeded up the development of RepA-induced cell death, unlike NbTsip1 silencing, which showed an opposite effect on RepA-induced response. Further study showed increased H2O2 accumulation and a negative correlation between the transcripts of NbFDN1 and NbTsip1 in NbFDN1-silenced plants. Hence, we speculate that NbFDN1 has an effect on RepA-induced hypersensitive response-like response by modulating NbTsip1 transcription as well as H2O2 production.

RepA Protein Encoded by Oat dwarf virus Elicits a Temperature-Sensitive Hypersensitive Response-Type Cell Death That Involves Jasmonic Acid-Dependent Signaling.

The hypersensitive response (HR) is a component of disease resistance that is often induced by pathogen infection, but essentially no information is available for members of the destructive mastreviruses. We have investigated an HR-type response elicited in Nicotiana species by Oat dwarf virus (ODV) and have found that expression of the ODV RepA protein but not other ODV-encoded proteins elicits the HR-type cell death associated with a burst of H2O2. Deletion mutagenesis indicates that the first nine amino acids (aa) at the N terminus of RepA and the two regions located between aa residues 173 and 195 and between aa residues 241 and 260 near the C terminus are essential for HR-type cell-death elicitation. Confocal and electron microscopy showed that the RepA protein is localized in the nuclei of plant cells and might contain bipartite nuclear localization signals. The HR-like lesions mediated by RepA were inhibited by temperatures above 30°C and involvement of jasmonic acid (JA) in HR was identified by gain- and loss-of-function experiments. To our knowledge, this is the first report of an elicitor of HR-type cell death from mastreviruses.

The nucleotide sequence of barley strain ofWheat dwarf virusisolated in Hungary

Barley-infecting isolates of WDV were collected in the field of near Sofia. The complete genomes of two isolates were amplified by PCR, cloned into pGEM-T plasmid and sequenced. The two clones were the same size and showed complete homology. The WDV-Bg17 clone was compared with Barley dwarf virus, Oat dwarf virus and Wheat dwarf virus isolates. Based on DNA sequences WDV-Bg17 isolate shows high homology (95–97%) to Barley dwarf virus isolates and differs from Oat dwarf virus (71% homology) and Wheat dwarf virus (85% homology).

Assessment of codivergence of mastreviruses with their plant hosts.

BackgroundViruses that have spent most of their evolutionary time associated with a single host lineage should have sequences that reflect codivergence of virus and host. Several examples for RNA viruses of host-virus tree congruence are being challenged. DNA viruses, such as mastreviruses, are more likely than RNA viruses to have maintained a record of host lineage association.ResultsThe full genomes of 28 isolates of Wheat dwarf virus (WDV), a member of the Mastrevirus genus, from different regions of China were sequenced. The analysis of these 28 entire genomes and 18 entire genome sequences of cereal mastreviruses from other countries support the designation of wheat, barley and oat mastrevirus isolates as separate species. They revealed that relative divergence times for the viruses WDV, Barley dwarf virus (BDV), Oat dwarf virus (ODV) and Maize streak virus (MSV) are proportional to divergence times of their hosts, suggesting codivergence. Considerable diversity among Chinese isolates was found and was concentrated in hot spots in the Rep A, SIR, LIR, and intron regions in WDV genomes. Two probable recombination events were detected in Chinese WDV isolates. Analysis including further Mastrevirus genomes concentrated on coding regions to avoid difficulties due to recombination and hyperdiversity. The analysis demonstrated congruence of trees in two branches of the genus, but not in the third. Assuming codivergence, an evolutionary rate of 10-8 substitutions per site per year was calculated. The low rate implies stronger constraints against change than are obtained by other methods of estimating the rate.ConclusionWe report tests of the hypothesis that mastreviruses have codiverged with their monocotyledonous hosts over 50 million years of evolution. The tests support the hypothesis for WDV, BDV and ODV, but not for MSV and other African streak viruses.

Surveying cereal-infecting geminiviruses in Germany—Diagnostics and direct sequencing using rolling circle amplification

Geminiviruses have spread in German cereal crops during the last few years. In order to identify and classify them, we have compared conventional techniques (enzyme-linked immunosorbent assays, polymerase chain reaction, bacterial cloning, and sequencing) with a newly developed method which uses rolling circle amplification (RCA), restriction fragment length polymorphism (RFLP), and direct sequencing without a bacterial cloning step. Whereas immunological methods utilising polyclonal antibodies were reliable for detection of geminiviruses, they did not discriminate between different German mastrevirus species, in contrast to RCA/RFLP. Direct sequencing gave high fidelity results with the same quality as conventional cloning and sequencing but with significantly reduced effort and costs. Based on a survey of field-derived cereal samples and on DNA sequences of distinct virus isolates we propose two new mastrevirus species, to be named Barley dwarf virus (BDV), and Oat dwarf virus (ODV) according to sequence differences and host range studies. The results show the applicability of RCA-based techniques for field studies and the possibility of sequencing a geminiviral genome without cloning. This approach will accelerate genomics studies of all viruses with small circular DNA genomes. In addition, RCA proves to be a reliable technique allowing for the detection of new geminivirus species as it does not depend on the knowledge of specific primers.

Use of enzyme amplification in an ELISA to increase sensitivity of detection of barley yellow dwarf virus in oats and in individual vector aphids

A new technique of alkaline phosphatase amplification in an ELISA (amplified ELISA) was used to increase the sensitivity of detection of barley yellow dwarf virus (BYDV) from oat plant sap and in individual vector aphids. Amplified ELISA differs from conventional direct double antibody sandwich ELISA (DAS-ELISA) in the enzyme substrate reaction. The bound enzyme-labelled antibody catalyzes the conversion of NADP to NAD which is then used in a secondary enzyme-mediated cyclic reaction producing a red-coloured end product. Amplified ELISA was compared with DAS-ELISA for the detection of BYDV and each assay was done with both monoclonal and polyclonal antibody reagents. Both types of antibodies detected BYDV from oat sap and amplified ELISA increased the sensitivity of detection sufficiently to allow a diagnostic test to be completed in less than 2 h using microtitre plates precoated with antibodies. However, in the amplified ELISA using polyclonal antibodies the absorbance values obtained with the healthy oat sap samples were much greater than those obtained in the DAS-ELISA, or with the monoclonal antibodies, and were too large to be acceptable for reliable diagnostic tests. Both monoclonal and polyclonal antibodies were used successfully to detect BYDV in individual virus-carrying Rhopalosiphum padi by amplified ELISA and there was little non-specific background reaction in the control samples with either of the antibodies.

Inheritance of tolerance to barley yellow dwarf virus in oats

Advanced generation random lines from crosses of tolerant x susceptible parents were studied to determine the inheritance of tolerance to barley yellow dwarf virus (BYDV) in oats Avena sativa L. Clintland 64, a susceptible oat cultivar, was crossed with the BYDV tolerant oat lines Otee, FF64/74, M921 and CI4492. Randomly selected lines were advanced to F5 or F6 by single seed descent and were tested for their reaction to BYDV at Palmerston North, New Zealand and Winnipeg, Manitoba and Ste-Foy, Quebec, Canada.

Heritability of Resistance to Barley Yellow Dwarf Virus in Oats1

Heritability of Resistance to Barley Yellow Dwarf Virus in Oats¹