Strains Of Barley Yellow Dwarf Virus Research Articles

Barley Yellow Dwarf Virus Influences Its Vector's Endosymbionts but Not Its Thermotolerance.

The barley yellow dwarf virus (BYDV) of cereals is thought to substantially increase the high-temperature tolerance of its aphid vector, Rhopalosiphum padi, which may enhance its transmission efficiency. This is based on experiments with North American strains of BYDV and R. padi. Here, we independently test these by measuring the temperature tolerance, via Critical Thermal Maximum (CTmax) and knockdown time, of Australian R. padi infected with a local BYDV isolate. We further consider the interaction between BYDV transmission, the primary endosymbiont of R. padi (Buchnera aphidicola), and a transinfected secondary endosymbiont (Rickettsiella viridis) which reduces the thermotolerance of other aphid species. We failed to find an increase in tolerance to high temperatures in BYDV-infected aphids or an impact of Rickettsiella on thermotolerance. However, BYDV interacted with R. padi endosymbionts in unexpected ways, suppressing the density of Buchnera and Rickettsiella. BYDV density was also fourfold higher in Rickettsiella-infected aphids. Our findings indicate that BYDV does not necessarily increase the temperature tolerance of the aphid transmission vector to increase its transmission potential, at least for the genotype combinations tested here. The interactions between BYDV and Rickettsiella suggest new ways in which aphid endosymbionts may influence how BYDV spreads, which needs further testing in a field context.

Incidence and Distribution of Barley yellow dwarf virus Infecting Oats in Korea

A survey of Barley yellow dwarf virus (BYDV) was conducted in major oat-growing areas of Korea in 2020. BYDV is an economically important pathogen of cereal crops that can be transmitted by aphids. The present study evaluated the genetic composition of BYDV in oat from eight geographical areas in Korea. Multiplex reverse transcription-polymerase chain reaction was used to screen 322 oat leaf samples for six BYDV strains (PAV, MAV, SGV, PAS, RPV, and RMV). The 125 samples (~39%) tested positive for BYDV. BYDV-PAV, BYDV-SGV, BYDV-PAS, and BYDV-RPV were detected from oat in different areas. Most of the BYDV-infected samples were assigned to subgroup I (n=112). The results indicate that BYDV-PAV could be dominant throughout Korea. Also, the phylogenetic analysis of coat protein sequences indicated that 23 BYDV isolates from Korea could be separated into two clades, which exhibited high nucleotide sequence similarity. In conclusion, the present survey provides a BYDV infection assessment for domestic oat varieties in Korea and basic information for the development of BYDV control measures in Korea’s oat industry.

Investigation of the mechanism of adult-stage resistance to barley yellow dwarf virus associated with a wheat–Thinopyrum intermedium translocation

Barley yellow dwarf virus (BYDV) can infect wheat (Triticum aestivum L.), leading to yield loss. Among four BYDV strains (GAV, GPV, PAV, and RMV) identified in China, BYDV-GAV is the prevailing isolate. YW642, a wheat–Thinopyrum intermedium translocation line, is resistant to BYDV isolates at both seedling and adult stages. Zhong 8601 is the wheat recurrent parent of YW642 and is susceptible to BYDV. In this study, we investigated the adult-stage resistance mechanism of YW642, measured BYDV titer and hydrogen peroxide (H2O2) in adult-stage leaves of YW642 and Zhong 8601 inoculated with BYDV-GAV, and identified transcriptional differences between YW642 and Zhong 8601 using microarray-based comparative transcriptomics. Enzyme-linked immunosorbent assay and H2O2 assay showed that both BYDV titer and H2O2 content were markedly lower in YW642 than in Zhong 8601 at 21, 28, 35, and 40days post-inoculation (dpi). The transcriptomic comparison revealed that many types of genes were significantly up-regulated at 35dpi in adult-stage leaves of YW642 compared to Zhong 8601. The important up-regulated genes associated with the adult-stage resistance encoded 15 resistance-like proteins, pathogenesis-related proteins (such as defensin and lipid transfer proteins), protein kinase homologs, transcription factors, reactive oxygen species scavenging-related proteins, and jasmonic acid and gibberellic acid biosynthesis enzymes. These results suggest that precise expression regulation of these proteins plays a crucial role in adult-stage resistance of YW642 against BYDV infection.

Development of monoclonal antibodies and serological assays specific for Barley yellow dwarf virus GAV strain

BackgroundBarley yellow dwarf virus (BYDV) is one of the most devastating plant viruses and belongs to a ubiquitous plant virus group. In China, four BYDV strains (GPV, GAV, PAV and RMV) have been identified based on their specific aphid vectors and serological properties. Among the four identified strains, the GAV is the most common BYDV strain in China. To diagnose, forecast of BYDV GAV, two reliable serological assays for BYDV GAV detection were established.MethodsWe purified virion from a confirmed BYDV GAV source and used it as the immunogen to produce monoclonal antibodies against the virus. Using the hybridoma technology, three highly specific murine monoclonal antibodies were produced and two serological assays [antigen-coated-plate enzyme-linked immunosorbent assay (ACP-ELISA) and dot enzyme-linked immunosorbent assay (dot-ELISA)] were established for the BYDV GAV detection.ResultsAll three monoclonal antibodies reacted strongly and specifically with the BYDV GAV strain in crude leaf extracts. Titers of the monoclonal antibodies in ascitic fluids were up to 10−7 by indirect-ELISA. These three monoclonal antibodies (18A1, 18A9 and 12A11) all belonged to the isotype IgG1, kappa light chain. The highest dilution points for the three antibodies during the ACP-ELISA using infected crude leaf extracts were 1:163,840, 1:81,920 and 1:81,920 (w/v, g · mL−1), respectively. Result of dot-ELISA showed a successful detection of BYDV GAV strain in 1:5,120 (w/v, g · mL−1) diluted wheat leaf crude extracts. Analysis of 22 field wheat leaf samples and 33 aphid samples from the Shaanxi Province in China, using the two newly developed assays confirmed the presence of BYDV GAV in about 80 % of the wheat samples and 18 % of the aphid samples.ConclusionsAll three monoclonal antibodies are highly sensitive and specific to the BYDV GAV. The two newly developed serological assays are simple and effective. These two assays, particularly the dot-ELISA, are useful for high throughput detection of BYDV GAV in host plants and aphid vectors.

The complete nucleotide sequence of the barley yellow dwarf GPV isolate from China shows that it is a new member of the genus Polerovirus

The complete nucleotide sequence of the ssRNA genome of a Chinese GPV isolate of barley yellow dwarf virus (BYDV) was determined. It comprised 5673 nucleotides, and the deduced genome organization resembled that of members of the genus Polerovirus. It was most closely related to cereal yellow dwarf virus-RPV (77% nt identity over the entire genome; coat protein amino acid identity 79%). The GPV isolate also differs in vector specificity from other BYDV strains. Biological properties, phylogenetic analyses and detailed sequence comparisons suggest that GPV should be considered a member of a new species within the genus, and the name Wheat yellow dwarf virus-GPV is proposed.

Screening for Barley yellow dwarf virus‐Resistant Barley Genotypes by Assessment of Virus Content in Inoculated Seedlings

AbstractThe content of Barley yellow dwarf virus (BYDV) in roots and leaves of barley seedling plants differing in their level of resistance was assessed by quantitative ELISA 1–42 days after inoculation with the strain of BYDV (PAV). High virus accumulation in roots and low concentration in leaves was characteristic of the period 9–15 days after inoculation. In leaves, the differences in virus content between resistant and susceptible genotypes became significant after 15 days and resistance to virus accumulation was better expressed 30–39 days after inoculation. Roots of resistant materials exhibited evident retardation of virus accumulation and the greatest difference in virus content between resistant and susceptible plants was detected 9 days after inoculation. By these criteria, the selected winter and spring barley cultivars and lines (in total 44 materials) fell in to five groups according to field reactions and the presence or absence of the Yd2 resistance gene. There were highly significant and positive relations between ELISA values and 5‐year field data on symptomatic reactions and grain‐yield reductions due to infection. Using the described method, resistant and moderately resistant genotypes (both Yd2 and non‐Yd2) were significantly differentiated from susceptible genotypes. The possible use of this method in screening for BYDV resistance is discussed.

Screening and analysis of differentially expressed genes from an alien addition line of wheatThinopyrum intermediuminduced bybarley yellow dwarf virusinfection

The alien addition line TAI-27 contains a pair of chromosomes of Thinopyrum intermedium that carry resistance against barley yellow dwarf virus (BYDV). A subtractive library was constructed using the leaves of TAI-27, which were infected by Schizaphis graminum carrying the GAV strain of BYDV, and the control at the three-leaf stage. Nine differentially expressed genes were identified from 100 randomly picked clones and sequenced. Two of the nine clones were highly homologous with known genes. Of the remaining seven cDNA clones, five clones matched with known expressed sequence tag (EST) sequences from wheat and (or) barley whereas the other two clones were unknown. Five of the nine differentially expressed sequences (WTJ9, WTJ11, WTJ15, WTJ19, and WTJ32) were highly homologous (identities >94%) with ESTs from wheat or barley challenged with pathogens. These five sequences and another one (WTJ18) were also highly homologous (identities >86%) with abiotic stress induced ESTs in wheat or barley. Reverse Northern hybridization showed that seven of the nine differentially expressed cDNA sequences hybridized with cDNA of T. intermedium infected by BYDV. Three of these also hybridized with cDNA of line 3B-2 (a parent of TAI-27) infected by BYDV. The alien chromosome in TAI-27 was microdissected. The second round linker adaptor mediated PCR products of the alien chromosomal DNA were labeled with digoxygenin and used as the probe to hybridize with the nine differentially expressed genes. The analysis showed that seven differentially expressed genes were homologous with the alien chromosome of TAI-27. These seven differentially expressed sequences could be used as ESTs of the alien chromosome of TAI-27. This research laid the foundation for screening and cloning of new specific functional genes conferring resistance to BYDV and probably other pathogens.

Barley yellow dwarf virus, wheat, and Sitobion avenae: a case of trilateral interactions

AbstractWe analysed interactions in the system of two Barley Yellow Dwarf Virus (BYDV) strains (MAV and PAV), and wheat (cv. Tinos) as host plant for the virus, and the cereal aphid Sitobion avenae (F.) as vector, in particular whether or not infection by the virus might alter host plant suitability in favour of vector development. By measuring the amino acid and sugar content in the phloem sap of infected and non‐infected wheat plants we found a significant reduction in the concentration of the total amount of amino acids on BYDV‐infected plants. Qualitative and quantitative analysis of honeydew and honeydew excretion indicated a lower efficiency of phloem sap utilisation by S. avenae on infected plants. In addition, S. avenae excreted less honeydew on infected plants. Both BYDV strains significantly affected aphid development by a reduction in the intrinsic rate of natural increase. Hence, infection by the virus reduced the host suitability in terms of aphid population growth potential on BYDV‐infected plants. However, more alate morphs developed on virus‐infected plants. These findings are discussed in relation to the population dynamics of S. avenae, and, as a consequence, the spread of BYDV.

Production of Barley yellow dwarf virus antisera by DNA immunization

Antibodies were produced against the 22-kDa coat protein (CP) of Barley yellow dwarf virus strain PAV (BYDV-PAV) by DNA immunization. A cDNA sequence encoding the 22-kDa CP was cloned into a mammalian expression vector (pcDNA22K), entrapped in liposomes, and injected intramuscularly into BALB/c mice. To target the antigen to sites of immune induction and, thereby, enhance the immune response, the 22-kDa sequence was also fused with the sequence encoding the mouse cytotoxic T-lymphocyte antigen 4 to generate pCTLA422K. Three weeks post immunization, BYDV-PAV-specific immune response was detected in serum. Sera from mice injected with pCTLA422K DNA had significantly higher antibody titers than those from mice injected with pcDNA22K. Increases in antibody titers were observed over time with each subsequent DNA injection. Further, there were large increases in antibody titers when DNA-immunized mice were boosted with purified BYDV-PAV virions. These antibody responses were higher than that obtained by a single injection of purified BYDV-PAV. The results demonstrate that antibodies against BYDV-PAV can be generated using DNA immunization. With this approach, it may be possible to produce antisera against luteoviruses that occur in low concentrations in host plant tissue and are very difficult to purify.

Yield Effects of Barley yellow dwarf virus in Soft Red Winter Wheat

ABSTRACT Three cultivars of soft red winter wheat were evaluated to determine the relationship between the incidence and time of infection by Barley yellow dwarf virus (BYDV) and yield. Wheat was planted in 1995, 1996, and 1997 in a split-plot design with six replicates at sites in Indiana and Illinois. Yield plots were infested with different amounts of viruliferous aphids, and the incidence of BYDV in each plot was measured. In a 2-year study in Illinois with cv. Clark and the PAV-IL isolate of BYDV, yields were assessed following aphid infestation in fall, early spring, and late spring. Early spring infections resulted in larger yield reductions than late spring infections in both years and larger than fall infections in one year. Regression analyses to relate incidence of infection and yield with data from fall and early spring infections provided R(2) values of 0.89 and 0.51 for the 1996 to 1997 and 1997 to 1998 seasons, respectively. An additional study at the same site in the 1996 to 1997 season compared the yield responses of cvs. Clark, Y88-3e, and PT8935b. Increases in the incidence of BYDV correlated with decreases in yield, with R(2) values of 0.80, 0.78, and 0.90 for the three cultivars, respectively. Estimated yield losses in both studies and all cultivars ranged from 27 to 45 kg/ha or 0.34 to 0.55% for each percent increase in virus infection. In a third study over a 2-year period in Indiana with the same three wheat genot ypes and a second BYDV isolate (PAV-P), BYDV treatments resulted in significant reductions in yield, but yield loss and the incidence of BYDV were not linearly correlated. Given the differences in yield reductions caused by the two BYDV isolates, PAV-P may be an attenuated strain of BYDV and may cross-protect plants from naturally occurring strains of the virus.

In Situ Localization of Barley Yellow Dwarf Virus-PAV 17-kDa Protein and Nucleic Acids in Oats

ABSTRACT Barley yellow dwarf virus strain PAV (BYDV-PAV) RNA and the 17-kDa protein were localized in BYDV-PAV-infected oat cells using in situ hybridization and in situ immunolocalization assays, respectively. The in situ hybridization assay showed labeling of filamentous material in the nucleus, cytoplasm, and virus-induced vesicles with both sense and antisense nucleic acid probes, suggesting that the filamentous material found in BYDV-PAV-infected cells contains viral RNA. BYDV-PAV negative-strand RNA was detected before virus particles were observed, which indicates that RNA replication is initiated before synthesis of viral coat protein in the cytoplasm. The 17-kDa protein was associated with filamentous material in the cytoplasm, nucleus, and virus-induced vesicles. The labeling densities observed using antibodies against the 17-kDa protein were similar in the nucleus and cytoplasm. No labeling of the 17-kDa protein was observed in plasmodesmata, but filaments in the nuclear pores occasionally were labeled. Since BYDV-PAV RNA and 17-kDa protein colocalized within infected cells, it is possible that single-stranded viral RNA is always associated with the 17-kDa protein in vivo. The 17-kDa protein may be required for viral nucleic acid filaments to traverse the nuclear membrane or other membrane systems.

Characterization of Wheatgrass-Derived Barley Yellow Dwarf Virus Resistance in a Wheat Alien Chromosome Substitution Line

ABSTRACT Wheatgrass (Thinopyrum intermedium) possesses a high level of resistance to barley yellow dwarf virus (BYDV) subgroup I and subgroup II strains. A wheat line (P29), in which the 7D chromosome has been substituted with a group 7 chromosome from T. intermedium, was examined for the level of resistance to two subgroup I and two subgroup II BYDV strains. In P29 plants inoculated with the subgroup I PAV strains, the titer of virus in leaf and stem tissue was typically reduced 42 to 52% when compared with the BYDV-susceptible cv. Abe. P29 and 'Abe' had the same content of PAV in roots. These results and the absence of detectable virus in inoculated T. intermedium plants indicate that the complete resistance to subgroup I possessed by the wheatgrass has not been introgressed into P29. In contrast, P29 was completely resistant throughout the plant to the subgroup II strains, NY-RPV and NY-RMV, demonstrating that the complete resistance to subgroup II in T. intermedium was incorporated into P29. Further analysis of this resistance to NY-RPV showed that NY-RPV can replicate in mesophyll protoplasts of P29 and 'Abe', suggesting that this resistance is not operating at the single-cell level. Molecular marker analysis confirmed that the T. intermedium chromosome present in P29 is a different group 7 wheatgrass chromosome than that present in L1, a wheat line with BYDV resistance properties similar to those of P29.

Identification of Quantitative Loci for Tolerance to Barley Yellow Dwarf Virus in Oat

ABSTRACT Molecular markers linked to quantitative trait loci conditioning tolerance to barley yellow dwarf virus (BYDV) were identified in oat (Avena sativa) using amplified fragment length polymorphism (AFLP) analysis. Near-isogenic and recombinant inbred lines (NILs and RILs, respectively) derived from a cross of Clintland64 (BYDV-sensitive) and IL86-5698 (BYDV-tolerant) were evaluated for their responses to an Illinois isolate of the PAV strain of BYDV. Individual markers identified in the analysis of the NILs explained up to 35% of the variability seen in the tolerance response. Single-point analysis of the marker data from the RIL population identified 24 markers in three linkage groups that were associated with tolerance to BYDV infection at P </= 0.001. These markers defined three major loci, A, C, and E, that were contributed by the tolerant parent (IL86-5698) and explained 35.0, 20.6, and 17.0% of the variability, respectively. Three minor loci G, H(1), and R) were identified at P </= 0.01. These loci were contributed by the sensitive parent (Clintland64) and explained 5.8, 5.6, and 5.6% of the variability, respectively. Interval analysis showed that only the loci A, C, and E are associated significantly with BYDV tolerance at log of the likelihood ratio >/= 3.0. These loci explained about 50% total of the variation in BYDV tolerance in multimarker regression analysis in both years. The BYDV tolerance loci A, C, E, and R were mapped to hexaploid oat restriction fragment length polymorphism linkage groups 2, 8, 36, and 5, respectively, by analyzing the segregation of the AFLP markers in the Kanota x Ogle RIL population.

Barley Yellow Dwarf Virus Strain Incidence in Small Grain Cereals in Northeast Spain

AbstractBarley yellow dwarf virus (BYDV) was detected in forage cereals and small grain cereals by indirect enzyme‐linked immunosorbent assay. Samples of forage cereals collected in the winters of 1987/1988, 1988/1989 and 1989/1990 showed that this crop is a reservoir of BYDV during the end of summer and autumn. PAV‐like and MAV‐like isolates, in single or mixed infection, were the most common. The proportion of isolates in the infected samples was relatively stable, Samples of winter cereals collected in the springs of 1988, 1989 and 1990 showed that PAV‐ and MAV‐like isolates were widespread. The proportion of samples infected with PAV‐like isolates was much more variable than that of MAV‐like isolates. The incidence of PAV‐like isolates in winter cereals is more dependent on the population of Rhopalosiphum padi during the winter and early spring, than is the incidence of MAV‐like isolates on Sitobion avenae density. In northeast Spain (Lleida basin) forage cereals are a constant source of PAV‐ and MAV‐ like isolates from which BYDV inoculum is introduced into winter cereals.

The incidence of strains of barley yellow dwarf virus in perennial ryegrass crops in south‐west and central Scotland

The incidence of barley yellow dwarf virus (BYDV) in perennial ryegrass (Lolium perenne) crops in four areas of south‐west and central Scotland was investigated between March 1988 and February 1989. BYDV was detected in 93·8% of the grass swards using an indirect enzyme‐linked immunosorbent assay (ELISA). This enabled the seasonal periodicity of the BYDV strains to be monitored over 12 months for the first time in Scotland. The incidence of the RPV, PAV and MAV strains of BYDV declined between March and July 1988, before gradually rising in August. Incidence increased markedly in September, especially of the RPV and MAV strains, and then gradually decreased over the winter months, before stabilizing in February 1989. The incidence of the different strains in perennial ryegrass leys varied between geographical areas and between fields within areas. Most ryegrass samples contained a mixture of the three strains of BYDV. RPV was the most common strain in Ayrshire, while the incidence of PAV was highest in Wigtownshire and that of MAV was highest in Dumfriesshire and Stirlingshire. The incidence of BYDV increased with the age of the sward. The role of perennial ryegrass as a source of virus for the infection of cereals is discussed.

Transmission of barley yellow dwarf virus by cereal aphids collected from different habitats on cereal farms

Cereal aphids were collected from cereal crops, from Poa annua within cereal fields, from Lolium perenne pastures and from wild grasses in hedge bottoms and around farm buildings. The frequency of barley yellow dwarf virus (BYDV) transmission was assessed by aphid transmission tests. There were differences in transmission rates between aphid species, between host species and between years. The transmission rates of Rhopalosiphum padi from the different host species were broadly similar whereas for Sitobion avenae, P. annua within cereal fields was significantly better than the other host species. Wild grasses other than P. annua were relatively poor sources of virus. A large percentage of aphids frequently transmitted more than one strain, suggesting that host plants are often infected with more than one BYDV strain.

Barley yellow dwarf virus in ryegrass and its detection by ELISA

The enzyme‐linked immunosorbent assay (ELISA) effectively detected PAV‐ and MAV‐like strains of barley yellow dwarf virus (BYDV) in ryegrass. MAV‐like BYDV was found in a large proportion of ryegrass plants with foliar symptoms. There was a poor association between foliar symptoms and PAV‐like virus, which occurred with similar frequency in plants with and without symptoms. By August 1982, plots of perennial, Italian and hybrid ryegrass sown at Auchincruive in 1980 were extensively infected with PAV‐ and MAV‐like strains of BYDV. Tests on samples from 1981‐ and 1982‐sown plots in August 1983 also indicated early invasion by BYDV. Infection levels of 7–80% were found in 13 commercial crops of perennial ryegrass surveyed near Auchincruive in May 1983. PAV‐like BYDV occurred with greater frequency than did MAV‐like strains of the virus.

Transmission of Barley Yellow Dwarf Virus Strains from Northwestern China by Four Aphid Species

Transmission of Barley Yellow Dwarf Virus Strains from Northwestern China by Four Aphid Species

The Median Latent Periods for Three Isolates of Barley Yellow Dwarf Virus in Aphid Vectors

The Median Latent Periods for Three Isolates of Barley Yellow Dwarf Virus in Aphid Vectors

Cross protection and mutual exclusion by three strains of barley yellow dwarf virus in Avena sativa L

Avena sativa L. var. Clintland 64 inoculated in the early one-leaf stage with a mild barley yellow dwarf virus strain was protected against subsequent invasion by either of two severe strains of the virus under field conditions. The protection was indicated by the failure of the second-introduced virus to induce characteristic symptoms and the failure to recover the second virus by specific vectors. When the oat seedlings were simultaneously inoculated with the three strains in the early one-leaf stage, mutual exclusion was observed; the plants showed mild symptoms soon after inoculation, but complete recovery followed and no virus could be recovered from the healthy appearing plants. The same phenomenon did not occur, however, when the plants were inoculated at a more advanced stage of growth: after later inoculation the infection induced a severe acute disease, typified by necrosis, from which the plants never recovered. These phenomena and other strain interactions were further substantiated by highly significant quantitative differences among plant characters that reflected the behavior of the virus strains within the host. It is suggested that the three strains of BYDV be regarded as closely related.