Barley Yellow Dwarf Research Articles

Effects of Confinement and Wheat Variety on the Performance of Two Aphid Species

Bird cherry-oat aphid (Rhopalosiphum padi L.; Hemiptera: Aphididae) and English grain aphid (Sitobion avenae Fabricius; Hemiptera: Aphididae) are economically important cereal crop pests and effective vectors of barley yellow dwarf virus (BYDV). While these aphid species have traditionally been managed with synthetic chemical insecticides, their use is increasingly difficult due to target organism resistance and potential non-target effects. Exploiting genetic diversity among cereal varieties offers a more sustainable control strategy. In this study, we evaluated how an experimental confinement method using clip cages to restrict an aphid to a single leaf versus free movement on the host plant affects the performance (growth and reproduction) of these two aphid species on various wheat varieties. Aphid performance was significantly influenced by both confinement and wheat variety. Notably, the two aphid species responded in opposite ways to confinement, with S. avenae growing quicker and producing a greater number of offspring under clip cage confinement compared to R. padi, which performed better when left free on the plant. This contrast is likely explained by species-specific feeding site preferences and sensitivity to the microenvironment created by the clip cages. We also found significant differences in aphid performance among host plant varieties, with both aphid species achieving their lowest growth rates on “Wolverine”, a modern BYDV-resistant wheat cultivar. Although none of the tested varieties were completely resistant to aphids, our results indicate that existing commercial cultivars may already carry partial resistance traits that can be leveraged in integrated pest management programs to help suppress aphid populations.

First Report on Wheat Dwarf India Virus Infecting Maize (Zea mays) in China.

Maize (Zea mays) is among the most extensively cultivated crops in China, serving as a crucial source of food, feed, and biofuel. Viral diseases, such as maize lethal necrosis, contribute significantly to corn yield losses (Mahuku et al. 2015; Jiao et al. 2022). In 2022, an infected maize plant exhibiting virus-like symptoms, including yellowing and dwarfing, was observed in Hainan, China (Supplementary Figure S1). To identify the pathogen responsible, leaf tissues were collected and their total RNA was extracted and assessed for quality. Then the plant was tested by RT-PCR for the following six viruses reported in China causing yellowing and/or dwarfing, including sugarcane mosaic virus, barley yellow dwarf virus, maize yellow mosaic virus, southern rice black streaked dwarf virus, maize chlorotic mottle virus and sorghum mosaic virus (Chen et al. 2016; Gu et al. 2023). None of the viruses was detected (Supplementary Figure S2). Subsequently, a cDNA library was constructed using the Small RNA Sample Pre Kit (Illumina, San Diego, USA), and sequencing was performed on the Illiumia Novaseq platform (Biomarker Technologies Corporation, Beijing, China). After eliminating low-quality reads, non-coding RNAs and duplicate reads, the remaining reads were assembled into long contigs using Velvet 1.0.5 software with a k-mer value of 17, resulting in 14 contigs ranging from 55 nt to 931 nt in length, showing nucleotide identity ranging from 94.52% to 100% with the genome of wheat dwarf India virus (WDIV, GenBank accession no. NC_017828.1). WDIV belongs to the genus Mastrevirus, family Geminiviridae, and possesses a monopartite circular single-stranded DNA genome of 2.5 to 2.7 kb (Kumar et al. 2014a). To validate the findings, total DNA was extracted from three symptomatic leaves, and the coat protein (CP) gene of WDIV was amplified using the PCR protocol with primers CP01 (5'-ATGTCTCAGGTGAAGAAGAGGAC-3') and CP02 (5'-CTACTGGTTGCCGATACTCTTGA-3') (Kumar et al. 2014b). With 99% coverage, a 744 bp fragment obtained displayed 96.10% similarity to the coat protein gene of wheat dwarf India virus clone (GenBank accession no. MN240337.1) (Supplementary Figure S3). To obtain the complete genome sequence of the virus, PCR with our own designed primers WDIV-2F (5'-ACAAGCATCCGACGAAGCAGA-3') and WDIV-2R (5'-AAATATTCTAATACAGGCACAGGCT-3') yielded a circular DNA of 2,871 bp. The amplicon was cloned into the pEASY-T1 cloning vector (Transgen, Beijing, China), and three independent positive colonies of Escherichia coli DH5α carrying the viral amplicon were sequenced. The nucleotide sequences obtained had 96.73%, 96.80%, and 96.84% nt identity with the complete gene of wheat dwarf India virus clone (GenBank accession no. MN240328.1) and were deposited in the GenBank database under accession numbers OR282786 - OR282788. To identify the occurrence and distribution of WDIV infection, 12 maize samples were collected from 2 different regions of Hainan province (Sanya and Wuzhishan) and tested using PCR with primers CP01 and CP02, the results showed that 2 samples collected in Sanya were positive (Supplementary Figure S4). Previous reports confirmed that WDIV infects barley, wheat, and sugarcane (Boulton et al. 2002). This study represents the first report of WDIV infecting maize in China, providing valuable insights into its host range and offering potential guidance for managing viral diseases in maize.

First finding of soil-borne cereal mosaic virus (SBCMV) infecting wheat in Slovenia.

The presence of soil-borne cereal viruses in Slovenia is understudied, therefore we conducted a small survey as part of Euphresco project Cerevir (2021-A-374). Barley (Hordeum vulgare) and wheat (Triticum aestivum) samples showing virus-like symptoms were collected in the years 2022 to 2024 in central and north-eastern Slovenia. The observed symptoms included yellow streaks and mosaic patterns, yellowing or reddening of the leaf tips. All collected samples were tested by double antibody sandwich ELISA (DAS-ELISA) for barley and cereal yellow dwarf viruses (BYDVs and CYDVs), wheat dwarf virus (WDV), barley mild mosaic virus (BaMMV), barley yellow mosaic virus (BaYMV), soil-borne cereal mosaic virus (SBCMV), soil-borne wheat mosaic virus (SBWMV), wheat spindle streak mosaic virus (WSSMV), barley stripe mosaic virus (BSMV) and wheat streak mosaic virus (WSMV), according to manufacturer's instructions (DSMZ/Bioreba). From 70 samples collected during the study period, three wheat samples from central Slovenia tested positive for SBCMV. Other viruses sporadically detected in tested samples were BYDVs, CYDVs and WDV. To confirm the DAS-ELISA results for SBCMV, total RNA was extracted from all samples using MagMAX-96 Total RNA Isolation Kit supplemented with Plant RNA Isolation Aid (both by Thermo Fischer Scientific) and reverse transcribed using High-Capacity cDNA Reverse Transcription Kit (Thermo Fischer Scientific) according to manufacturer's instructions. SBCMV was detected using qPCR described by Marra et al. (2023). Only the three DAS-ELISA-positive samples were confirmed to be positive by this method. SBCMV was shown to cause significant yield losses by up to 50% in susceptible winter wheat cultivars (Clover et al. 1999) and even by 70% when infecting durum wheat (Vallega and Rubies Autonell 1985). It was already identified in wheat, rye and their hybrid triticale, and reported from different countries, including UK, France, Germany, Denmark, Italy and Poland (Budge et al. 2008). The results indicate low abundance of the virus in Slovenian production fields. To the best of our knowledge, this is the first report of SBCMV detection in cereals in Slovenia. Polymyxa graminis vector of SBCMV is widespread in Europe (Kanyuka et al. 2003); however there are no records of its presence in Slovenia. Further studies on the presence and distribution of P. graminis in Slovenia are needed to evaluate the importance of this finding for Slovenian wheat production.

Resistance against Barley yellow dwarf virus: characterization of Ryd2 and Ryd3 genes in barley

Resistance against Barley yellow dwarf virus: characterization of Ryd2 and Ryd3 genes in barley

RNAi-mediated silencing of CYP4G15 correlates with altered transmission of barley yellow dwarf virus in Sitobion avenae (Fabricius)

RNAi-mediated silencing of CYP4G15 correlates with altered transmission of barley yellow dwarf virus in Sitobion avenae (Fabricius)

Metabolite-based resistance in wheat varieties to aphid virus vectors: progress and future opportunities.

Cereal aphids, Sitobion avenae and Rhopalosiphum padi, cause severe yield loss in wheat crops as a consequence of direct feeding damage and acting as vectors for Barley Yellow Dwarf Virus (BYDV). Insecticides have commonly been used to control these pests, but the advent of insecticide resistance spreading across aphid populations and the push to reduce insecticide use means that new approaches to control aphid populations are required. Wheat varieties with metabolite-based aphid resistance have been identified, suggesting that they could be developed as an alternative to insecticides. Resistance induced by natural products (metabolites) include volatile organic compound-mediated (antixenotic) and development-modifying (antibiotic) processes. Full characterisation of these resistance mechanisms is still required, and associated challenges, such as the influence of biotic and abiotic interactions, need to be addressed prior to their implementation into integrated pest management (IPM) or engineered into modern elite wheats. In this review, current literature on metabolite-based S. avenae and R. padi resistance in wheat is discussed, outlining current knowledge gaps and challenges, and highlighting the future work required. © 2025 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Genome‐wide association study identifies novel associations with barley yellow dwarf virus and soil‐borne wheat mosaic virus resistance in winter wheat association mapping panel

AbstractViral pathogens adversely affect wheat (Triticum aestivum L.) development and are responsible for significant wheat yield losses. Barley yellow dwarf virus (BYDV) is one of the most serious worldwide virus threats to cereal crops. Soil‐borne wheat mosaic virus (SBWMV) has been present in the Great Plains and responsible for wheat damage for over a century. Identification of additional sources of genetic resistance is paramount to combat the potential damage from these viruses. We constructed a panel of 269 winter wheat cultivars and breeding lines to assess the resistance to naturally occurring BYDV and SBWMV in a Kansas nursery. These lines were sequenced using exome and promoter capture identifying over 640,000 variants for association analysis with visual disease severity ratings. We found 10 and seven significant regions affecting resistance to BYDV and SBWMV, respectively. These regions include the Bdv2 and Sbwm1 loci, as well as novel loci affecting virus resistance. Most of the novel associations are rare, with effect sizes ranging from 5% to 22%. We performed a survey of the viral population present in the disease nursery, which confirmed the presence of both BYDV and SBWMV and revealed differences in virus population from year to year. Additionally, it suggested that co‐infections of multiple viruses are common, demonstrating the need for breeding lines harboring resistance to multiple viruses. Deployment of these novel genetic resistance regions in combination with existing resistance loci should allow for increased resistance and potentially more sustainable viral control and reduce the risks associated with wheat yield loss due to these viruses.

Patterns of mixed virus infections: a 3-year study of symptomatic cereal and grass hosts in Australia

Context Yellow dwarf viruses (YDVs) form a complex of economically important pathogens that can significantly reduce grain yield in cereals. Mixed infections, or infection with two or more YDV species, can be particularly damaging. Aims We aimed to examine the proportion of single and multiple virus infections present in symptomatic cereal and grass plants in Victoria, south-eastern Australia. Methods Over 3 years (2020–2022), symptomatic cereal and grass plants from within and around cereal fields in Victoria, Australia were individually tested using tissue-blot immunoassay (TBIA) for barley yellow dwarf virus PAV, barley yellow dwarf virus MAV, cereal yellow dwarf virus RPV, wheat streak mosaic virus, and with a generic TBIA test that can detect multiple luteovirus and/or polerovirus species. Key results Across 2020–2021, 34% of virus-positive plants were infected with multiple YDV species. The proportion of mixed infections was similar in each individual year. However, higher proportions of wheat (Triticum aestivum, 47%) and wild oat (Avena fatua, 36%) plants were infected with multiple YDV species compared to barley (Hordeum vulgare, 8%) and brome grass (Bromus spp.,17%). Conclusions The proportion of virus-positive plants infected with multiple YDV species found was almost four times higher than previously reported in a similar study in Victoria, Australia in 1985. The proportion of plants infected with multiple YDV species varied more with host type than between individual years. Implications These findings demonstrate the complex epidemiology of these damaging viruses, and the challenges associated with developing virus-resistant cereal cultivars, while also highlighting the importance of regular surveillance over multiple years.

Yellow dwarf viruses: aphid transmission efficiency and cereal host range.

Yellow dwarf viruses (YDVs) are transmitted by aphids and can significantly reduce grain yield in cereals worldwide. While barley yellow dwarf virus PAV (BYDV PAV) has long been present in Australia, the YDV species barley virus G (BVG) and barley yellow dwarf virus PAS (BYDV PAS) were reported for the first time more recently. Little data about the transmission and host range of BVG has been published worldwide, while epidemiological information about BVG and BYDV PAS in an Australian context is limited. Therefore, glasshouse experiments were conducted to examine the efficiency of the bird cherry-oat aphid (Rhopalosiphum padi), corn leaf aphid (Rhopalosiphum maidis), rose grain aphid (Metopolophium dirhodum) and Russian wheat aphid (Diuraphis noxia) to transmit BVG, BYDV PAS and BYDV PAV. BYDV PAS and BYDV PAV were transmitted at similar rates by each of the four aphid species. Although BVG was most efficiently transmitted by the corn leaf aphid, it was also transmitted, albeit less efficiently, by the bird cherry-oat aphid. Significantly, in our study, the corn leaf aphid transmitted BVG at a much higher rate (63%) using single-aphid inoculations than had previously been reported by others (7%). Varying levels of susceptibility were observed in host range experiments, and four additional BVG hosts were identified. Russian wheat aphid did not transmit any of the viruses examined. These results have implications for YDV management while also demonstrating the complexity and specificity of the relationships between YDVs, the aphids that transmit them and the plant hosts that they infect.

Sustainable control of the bird cherry-oat aphid (Rhopalosiphum padi L.) in northwestern Ontario using Beauveria bassiana delivered by bumblebees.

Rhopalosiphum padi is one of the main vectors of barley yellow dwarf virus (BYDV), which affects the grain yield of oats. Several biological control strategies have been studied to control this pest, one of which is Bee Vectoring Technology (BVT) using bumblebees. We tested the efficacy of Beauveria bassiana, as vectored by bumblebees, and a direct spray application of neem (a natural bio-insecticide derived from the Azadirachta indica tree) on aphids. An assessment of the pest's impact on the plots surveyed in northwestern Ontario revealed incidence rates of 80%. The use of bumblebees as a dispersal agent of B. bassiana significantly reduced the aphid population (0.542 ± 0.147b) compared to the untreated control (0.125 ± 0.069a). The application of diluted neem also showed a reduction in the aphid population (0.708 ± 0.221a). Although the products used controlled the pests, they had no effect on the aphid's natural enemy, the ladybug. Therefore, the dissemination of B. bassiana by the bumblebee Bombus impatiens leads to a decrease in the vector Rhopalosiphum padi population and consequently reduces the severity of barley yellow dwarf disease in oat fields.

The plant growth-promoting rhizobacterium Azospirillum brasilense reduces symptoms and aphid population growth on wheat plants infected with barley yellow dwarf virus.

There is increasing interest in the potential of plant growth-promoting rhizobacteria (PGPR) in agriculture to improve plant quality and control pests and diseases. Emerging evidence indicates that some PGPR can influence interactions between plants and their pathogens, while less work has explored whether PGPR may also influence interactions between plants and arthropod vectors. We address this issue in a major agricultural pathosystem involving wheat infection by barley yellow dwarf virus (BYDV), the most economically important aphid-transmitted viral disease of cereal crops. We found that plant association with the PGPR Azospirillum brasilense mitigated both viral effects on plant growth and population growth of the BYDV aphid vector, Rhopalosiphum padi. Although effects varied across A. brasilense strains, PGPR treatments that attenuated virus effects were also associated with reduced induction of salicylic acid in response to infection, suggesting PGPR inoculation may induce systemic resistance against BYDV. These findings suggest that PGPR may have significant capacity for application in the sustainable management of crop growth. However, further investigation of the complex interactions among PGPR, plants, pathogens and their vectors is needed to better understand this potential.

A novel quantitative trait locus for barley yellow dwarf virus resistance and kernel traits on chromosome 2D of a wheat cultivar Jagger.

Barley yellow dwarf (BYD) is one of the most serious viral diseases in cereal crops worldwide. Identification of quantitative trait loci (QTLs) underlining wheat resistance to barley yellow dwarf virus (BYDV) is essential for breeding BYDV-tolerant wheat cultivars. In this study, a recombinant inbred line (RIL) population was developed from the cross between Jagger (PI 593688) and a Jagger mutant (JagMut1095). A linkage map of 3106 cM consisting of 21 wheat chromosomes was developed using 1003 unique single nucleotide polymorphisms (SNPs) from the RIL population and was used to identify QTLs for BYDV resistance and yield-related traits, including 1000-kernel weight (TKW), kernel area (KA), kernel width (KW), and kernel length (KL). QByd.hwwg-2DL, a QTL on chromosome arm 2DL for BYDV resistance, was consistently identified in three field experiments and explained 11.6%-44.5% of the phenotypic variation. For yield-related traits, six major and repeatable QTLs were identified on 1AS (QKa.hwwg-1AS), 2DL (QTkw.hwwg-2DL, QKa.hwwg-2DL, QKw.hwwg-2DL, and QKl.hwwg-2DL), and 5AL (QKw.hwwg-5AL). The major QTLs on chromosome 2DL for TKW, KA, KW, and KL were mapped between 621 and 643 Mb, overlapping with QByd.hwwg-2DL with all the favorable alleles from Jagger. This study reports the first native BYDV resistance QTL (QByd.hwwg-2DL) originating from common wheat and tightly linked markers to the QTL for improvement of wheat BYDV resistance in wheat breeding.

A persistent bacterial Regiella transinfection in the bird cherry-oat aphid Rhopalosiphum padi increasing host fitness and decreasing plant virus transmission.

The bird cherry-oat aphid, Rhopalosiphum padi, is a major pest of agriculture due to its ability to directly damage crops and transmit plant viruses. As industries move away from chemical pest control, there is interest in exploring new options to suppress the impact of this pest. We describe the production of a transinfected line of R. padi carrying the bacterial endosymbiont, Regiella insecticola, originating from the green peach aphid, Myzus persicae. We show that Regiella increases the fitness of its novel host despite decreasing fitness in its native host. Regiella also shows a low level of horizontal transmission. Importantly the infection suppresses the ability of R. padi to transmit the barley yellow dwarf virus which damages wheat plants. Our results suggest this Regiella transinfection could be released to suppress virus transmission by aphids with its ability to persist and spread in situations where damage from the virus exceeds that from direct feeding by the aphid. © 2025 Society of Chemical Industry.

Effect of Barley Yellow Dwarf Virus (BYDV) on Barley: A Precise Assessment of Reductions in Yield Components Under Variable Disease Severities.

Understanding the effects of barley yellow dwarf virus (BYDV) on crop agronomic traits and yield performance helps breeders balance their selection criteria and farmers decide if pesticides should be applied to control aphids that distribute the virus. To precisely assess the deterioration of different agronomic traits and yield components caused by different levels of BYDV infection, seeds of a BYDV-sensitive barley cultivar RGT Planet were space sown in a field plot with 10 cm between seeds and 20 cm between rows under two consecutive years. When BYDV symptoms were shown, plants with different levels (0 to 5) of BYDV infection were tagged. For accurate comparisons, the neighboring non/less-infected plants were also tagged. At maturity, different agronomic traits and yield components were measured on those tagged plants. Results showed a strong linear correlation between BYDV severity and the performance of agronomic traits and yield components. The yield reductions ranged from 30% for the least affected (score of 1) to 90% for the severely affected (score of 5). Our research confirmed previous findings that BYDV seriously affects crop yield and the prediction of yield loss due to BYDV infection should use the percentage of plants with different BYDV symptoms.

Identification of barley yellow dwarf virus strains and genetic analysis of GAV strains in Qinghai Province

Barley yellow dwarf disease, caused by barley yellow dwarf virus (BYDVs), significantly affects global wheat crop production. It has reached epidemic proportions in the Qinghai Province, China. To explore the primary epidemic strains, genetic evolution, and molecular characteristics of the disease, 90 samples were collected from various locations in Qinghai Province between July and September 2019. Molecular identification and genetic analysis identified BYDV-GAV as the predominant strain in Qinghai Province, with a detection rate of 92%. We successfully cloned 44 BYDV-GAV isolates with genome lengths of approximately 5.7 kb. Molecular population genetics analysis indicated low genetic divergence (genetic distance <0.1) among the geographical populations of BYDV-GAV in Qinghai Province. The low FST values (<0.33) and high Nm values (2.65–6.21) suggested significant gene flow and reduced genetic differentiation between isolates. Tajima’s D value was negative, and the dN/dS value of the CP gene exceeded 1, indicating non-synonymous mutations, positive selection pressure, or diversified selection in the BYDV-GAV isolates from Qinghai Province. Phylogenetic analysis revealed nine distinct groups with a sequence similarity of 99% among the BYDV-GAV isolates, suggesting a common ancestral origin. These findings imply the relative stability of the disease in the Qinghai Province.

A viral p3a protein targets and inhibits TaDOF transcription factors to promote the expression of susceptibility genes and facilitate viral infection.

The interactions among viruses and host plants are complex and fascinating because these organisms interact with and adapt to each other continuously. Many plant transcription factors play important roles in plant growth and development and in the resistance to viral infection. To facilitate the infection of plants, some viral proteins typically target and inhibit the function of plant transcription factors. In this study, we found an interesting phenomenon wherein the p3a protein of barley yellow dwarf virus (BYDV) can interact with the zinc finger domain of the TaDOF transcription factor in wheat; the zinc finger domain of TaDOF can interact with the promoter of TaHSP70 and inhibit the transcription of the TaHSP70 gene; and p3a interacts with the TaDOF zinc finger domain through competitive binding, alleviating TaDOF zinc finger domain-mediated inhibition of the TaHSP70 promoter, thereby promoting TaHSP70 expression and promoting infection by BYDV. This study demonstrates that BYDV p3a is an immunosuppressive factor and enriches our understanding of the pathogenesis of BYDV.

Barley yellow dwarf virus in winter barley: Control in light of resistance issues and loss of neonicotinoid insecticides

AbstractBarley yellow dwarf virus (BYDV) is the most widespread viral disease of cereal crops vectored by aphids, causing stunting of the crop and significant yield loss. Management recommendations for autumn sown cereals has centred on the timely control of aphid vectors, particularly their management before the crop has reached Growth Stage 31 (stem elongation). In recent years two separate but related issues have emerged, (i) the detection of pyrethroid resistance in a single Sitobion avenae SA3 clone and (ii) the withdrawal of neonicotinoid insecticide seed dressing; widely used to manage aphids in the early development of cereal crops. A series of replicated field studies were conducted from 2016 to 2019 to ascertain if the pyrethroid insecticide is still effective in light of the SA3 clones' presence in aphid populations and if withdrawal of neonicotinoid seed dressings has negatively affected aphid management. Both disease levels and yields confirmed that the neonicotinoid, clothianidin, applied as a seed treatment significantly contributed to the management of BYDV in the different trials investigated. Results of this study demonstrate application of a foliar (lambda‐cyhalothrin or a sulfoxaflor) insecticide has a significant positive impact on yield. Foliar pyrethroid insecticides were as effective in protecting yield from BYDV as the neonicotinoid seed treatments. In the absence of neonicotinoid seed dressing, alternative insecticides still offer protection for winter barley crops against the aphid vectors of BYDV and associated yield loss. Furthermore, the presence of a pyrethroid resistant Sitobion avenae SA3 clone had no observable impact on field efficacy of the pyrethroid insecticide, lambda‐cyhalothrin in these trials. However, this needs continuous monitoring because of potential further increases in resistance levels or emergence of additional resistance mechanisms, which could render pyrethroid insecticides ineffective.

Catalase regulation during plant-virus-vector interaction.

Plant-virus-host interaction is a complex process involving several players. A constant arms race between the hosts and viruses has led to their co-evolution. Reactive oxygen species (ROS) are important signaling molecules that regulate plant growth, development, and stress responses. Barley yellow dwarf virus (BYDV) has a wide host range and infects several plant species such as barley, rice, oats, wheat, etc. A recent study by Tian et al. (2024) has highlighted that the movement protein (MP) of BYDV is involved in manipulation of the host ROS pathway to promote viral multiplication as well as transmission. The findings display the multifaceted role of a viral protein that is otherwise involved in movement. The limited coding ability of viruses is compensated by their proteins having multiple roles in the modulation of several different host molecular pathways. This is one of the key reasons for viruses being successful pathogens despite their limited coding ability.

Fine mapping a QTL for BYDV-PAV resistance in maize

Barley yellow dwarf (BYD) is one of the economically most important virus diseases of cereals worldwide, causing yield losses up to 80%. The means to control BYD are limited, and the use of genetically resistant cultivars is the most economical and environmentally friendly approach. The objectives of this study were i) to identify the causative gene for BYD virus (BYDV)-PAV resistance in maize, ii) to identify single nucleotide polymorphisms and/or structural variations in the gene sequences, which may cause differing susceptibilities to BYDV-PAV of maize inbreds, and iii) to characterize the effect of BYDV-PAV infection on gene expression of susceptible, tolerant, and resistant maize inbreds. Using two biparental mapping populations, we could reduce a previously published quantitative trait locus for BYDV-PAV resistance in maize to ~ 0.3 Mbp, comprising nine genes. Association mapping and gene expression analysis further reduced the number of candidate genes for BYDV-PAV resistance in maize to two: Zm00001eb428010 and Zm00001eb428020. The predicted functions of these genes suggest that they confer BYDV-PAV resistance either via interfering with virus replication or by inducing reactive oxygen species signaling. The gene sequence of Zm00001eb428010 is affected by a 54 bp deletion in the 5`-UTR and a protein altering variant in BYDV-PAV-resistant maize inbreds but not in BYDV-PAV-susceptible and -tolerant inbreds. This finding suggests that altered abundance and/or properties of the proteins encoded by Zm00001eb428010 may lead to BYDV-PAV resistance.

Direct effects of barley yellow dwarf virus on the performance, parasitoid resistance, and feeding behavior of its vector Sitobion avenae (Hemiptera: Aphididae).

The complex interaction between plant viruses and their insect vectors is the basis for the epidemiology of plant viruses. The 'Vector Manipulation Hypothesis' (VMH) was proposed to demonstrate the evolution of strategies in plant viruses to enhance their transmission to new hosts through direct effects on insect vector behavior and/or physiology. However, the aphid vectors used in previous studies were mostly obtained by feeding on virus-infected plants and as a result, it was difficult to eliminate the confounding effects of infected host plants. Furthermore, the mechanisms of the direct effects of plant viruses on insect vectors have rarely been examined comprehensively. We fed Sitobion avenae on an artificial diet infused with a purified suspension of Barley yellow dwarf virus (BYDV) PAV strain to obtain viruliferous aphids. We then examined their growth and reproduction performance, resistance to the parasitoid Aphidius gifuensis Ashmead, and feeding behavior. The results indicate that (1) viruliferous aphids had a shorter life span and a lower relative growth rate at the nymphal stage; (2) A. gifuensis had a lower parasitism rate, mummification rate, and emergence rate in viruliferous aphids; (3) Viruliferous aphids spent more time on non-probing and salivation behavior and had a shorter total duration of penetration and ingestion compared with healthy conspecifics. These results suggest that plant virus infection may directly alter vector fitness and behavior that improves plant virus transmission, but not vector growth. These findings highlight the mechanisms of VMH and the ecological significance of vector manipulation by plant viruses, and have implications for plant virus disease and vector management. © 2024 Society of Chemical Industry.