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.     

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.     

Analyzing and Modeling Temporal Disease Progress of Barley yellow dwarf virus Serotypes in Barley Fields

ABSTRACT Population dynamics of Padi avenae (PAV), Macrosiphum avenae (MAV), and Rhopalosiphum padi (RPV) virus serotypes of Barley yellow dwarf virus (BYDV) and of their main aphid vectors were studied in winter barley (Hordeum vulgare) fields for three successive years in western France. An epidemiological model of the spread of viruses in the field was developed based on vector populations as forcing variables and the population dynamics of each virus serotype. This model accurately simulated the kinetics of the epidemic for PAV serotypes, which are the most common ones. For RPV and to some extent for MAV, the results were less satisfactory. The occurrence and spread of PAV and MAV serotypes in the field was clearly and easily related to that of their main vector species. Conversely, the spread of RPV serotypes showed no consistent relationships with the dynamics of their vectors. Incidence of PAV in 1989 to 1990 and 1990 to 1991 showed a bimodal distribution, with maximums in fall (December) and spring (May) that were linked to fall infestations by R. padi and spring infestations by three (R. padi, Sitobion avenae, and Metopolophium dirhodum) or two (S. avenae and M. dirhodum) aphid species. In 1991 to 1992, the PAV infection curve was monomodal and mainly due to a primary spread of the virus by very large populations of alate R. padi. MAV incidence was low in fall and winter and reached a maximum in spring 1990 and 1991 related to the occurrence of S. avenae and M. dirhodum. RPV incidence was low every year, despite the abundance of its vector, R. padi. Mixed infections were more frequent than expected by chance and were assumed to be partly related to heterologous encapsidation. The occurrence of each serotype is discussed in relation to the time of crop infection and possible damage.     

感染大麦黄矮病毒的小麦中vsiRNA特征分析

 RNA沉默是植物中一种保守的抗病毒机制,其以大量病毒来源的小干扰RNA(virus-derived small interfering RNAs,vsiRNAs)的产生为标志,病毒在侵染寄主过程中可通过vsiRNAs靶向寄主转录本以对抗这种防御机制。BYDV-GAV引起的小麦黄矮病导致小麦黄化和矮化症状,对小麦生产构成严重威胁。通过深度测序技术,分析了感染BYDV-GAV的感病小麦品种‘小偃6号’中vsiRNAs的特征,共得到11 384个vsiRNAs,并预测到37 784个寄主靶基因。发现来源于BYDV-GAV基因组的正义和反义链的vsiRNAs的数量分布大致相等,在5’末端具有A和C偏好性,长度主要在21nt~22nt。靶基因的功能分析表明这些靶基因参与了广泛的生物学功能,尤其是在寄主-病原物互作中占的比重最大。选取25个参与寄主-病原互作的抗性相关基因进行定量验证,发现接种BYDV-GAV后有15个明显下调,6个上调,4个微弱下调,表明测序结果和靶基因预测可靠。推测BYDV-GAV可以通过vsiRNAs干扰寄主抗性基因表达和信号转导,从而实现对感病寄主的侵染。研究结果对揭示BYDV-GAV与小麦互作的分子机制具有重要意义。     

The Basis for Thinopyrum-Derived Resistance to Cereal yellow dwarf virus

ABSTRACT Incorporation of Thinopyrum intermedium-derived resistance genes into improved wheat germ plasm generated a wheat substitution line (P29) which is completely resistant to Cereal yellow dwarf virus (CYDV). The undetectable CYDV titer in P29 led many to conclude that resistance prevented viral replication. To determine whether CYDV replication or movement is inhibited, we examined inoculated leaves for replication and uninoculated leaves for systemic spread. CYDV subgenomic RNA, produced only during replication, was found within the inoculated area of P29 and T. intermedium leaves, demonstrating that viral replication occurred. Absence of CYDV from uninoculated, newly emerging leaves of inoculated P29 and T. intermedium plants indicated resistance via inhibition of viral systemic infection. Resistance was not effective if P29 was inoculated with 50 to 100 viruliferous aphids per plant at the first-leaf stage or younger, resulting in a systemic spread of CYDV. As these infected P29 seedlings continued to grow, the resistance phenotype was recovered. Our data suggested that T. intermedium-derived resistance to CYDV was primarily dosage dependent and could be developmentally regulated if the amount of inoculum was large enough.     

Plant community diversity influences vector behaviour and Barley yellow dwarf virus population structure

The species composition of a plant community can affect the distribution and abundance of other organisms including plant pathogens. The goal of this study was to understand the role of host diversity in the transmission of two Barley yellow dwarf virus (BYDV) species that share insect vectors and hosts. Greenhouse experiments measured the transmission rate of BYDV species PAV and PAS from infected oat plants to healthy agricultural and wild grasses and from these species back to healthy oat seedlings. In the field component of the study, the rate of spread of PAV and PAS was measured in monoculture plots planted with agricultural grasses. In greenhouse experiments, the aphid vector more readily transmitted PAV from agricultural grasses and more readily inoculated PAS to the wild grass species assayed. In the field experiment, disease prevalence was greater in wheat, but there was no difference in the rate of spread of PAV and PAS. These results indicate an interaction between vector and host genotype that selects for greater PAV transmission in grain crops, contributes to differences in disease prevalence between grass types, and maintains pathogen diversity within the larger plant community (i.e. agricultural and non‐agricultural hosts).     

青海省小麦种质资源对大麦黄矮病毒的抗性鉴定

为明确青海省不同小麦种质资源对大麦黄矮病毒(Barley yellow dwarf virus,BYDV)的抗性差异,于2014—2015年采用堆测法人工接种鉴定了178份种质资源的抗病性。结果显示,不同小麦种质资源对黄矮病的抗性存在较大差异,甘A100、川766、陕1059、兰麦-2的病情指数依次为14.83、23.60、23.99和24.66,表现出较好的抗病性;病情指数在50.00以上的高感品种有69份,包括尕老汉、白板麦、兴热密穗等,其中白板麦病情指数高达72.35,高于感病对照阿勃;其余种质资源病情指数在25.00~50.00之间,表现为感病;甘A101、甘A99、藏515、藏519、木汉麦、群科大白麦、拉胎板麦、小红麦-2和朗县折达25初期表现感病,后期恢复健康,有一定的耐病性;抗病性不同的种质资源感染BYDV后,对小麦产量的影响差异很大,抗病对照中4产量损失8.96%,耐病品种产量损失在13.64%~19.74%之间,高病品种尕老汉产量损失达41.91%,表明小麦种质资源中抗BYDV的品种极少。     

PP 1/70 (4) Aphid vectors of Barley yellow dwarf virus

Specific scope

This Standard describes the conduct of trials for the efficacy evaluation of insecticides against aphid vectors of Barley yellow dwarf virus.

Specific approval and amendment

First approved in 1983‐09. Aligned with revised standard text in 1997. Revision approved in 2005‐09 and 2017‐09.     

大麦黄矮病毒GPV与GAV株系间异源装配现象的初步研究

 以我国麦区的大麦黄矮病毒GPV、GAV株系为材料,利用它们的蚜传特异性,将由禾谷缢管蚜传播的GPV和由麦长管蚜传播的GAV混合侵染到岸黑燕麦上,并进行继代传毒。混合侵染后代蚜传表现型的变化初步表明存在异源装配现象,且表现型混合发生的比例较高。用DAS-ELISA和RT-PCR法对混合侵染后代进行了测定,进一步证明了异源包装现象的存在。部分基因的核苷酸序列分析初步显示所测定的混合侵染后代中没有发生基因重组。     

Aphid Abundance on Cereals in Autumn Predicts Yield Losses Caused by Barley yellow dwarf virus

ABSTRACT Barley yellow dwarf virus (BYDV) damage to winter cereals and population dynamics of the aphid Rhopalosiphum padi during fall were monitored in fields during 10 years at various locations in the northern half of France. Logistic regression was used to examine whether a simple risk probability algorithm based only on the autumnal population dynamics of R. padi can accurately predict yield losses caused by BYDV and, therefore, the need for insecticide treatment. Results showed that the area under the curve of the percentage of plants infested by R. padi during autumn was highly significantly related to BYDV yield losses. Then, a cost/benefit analysis was performed to estimate the optimal decision threshold resulting in the lowest annual average costs of BYDV damage and control. A "model use" strategy allowed a reduction in the annual average costs of BYDV disease and control of up to 36% when compared with a "prophylactic spraying" strategy. The optimal decision threshold was highly sensitive to variation in disease prevalence. This property was used to propose an easy way to adapt the model to any production situation through the determination of the most accurate decision threshold.     

Effect of combining two genes for partial resistance to Barley yellow dwarf virus-PAV (BYDV-PAV) derived from Thinopyrum intermedium in wheat

In this study two sources of resistance to Barley yellow dwarf virus (BYDV), both originating from Thinopyrum intermedium , were combined in a single genotype, line ZT, using GISH (genomic in situ hybridization) and a new molecular marker of the partial resistance gene Bdv2 . Susceptible wheat cv. Sunstar, the translocation line TC14 carrying Bdv2 , the addition line ZH with the group-2 chromosome arm carrying resistance, and line ZT with both resistances were inoculated with five strains of Barley yellow dwarf virus -PAV. The tests confirmed the resistance of TC14 and ZH and revealed an additive effect of the two sources of resistance in ZT. The resistance of line ZT was characterized by a proportion of infected plants significantly lower than the parental lines TC14 and ZH (42% vs. a mean of 76% for the parents) and a very low virus titre (area under the virus concentration progress curve of 1·2 vs. a mean on 6·3 for the parents).     

应用农杆菌介导法获得转大麦黄矮病毒GPV株系复制酶基因ORF1的小麦植株

 以生产用4种基因型小麦为材料,利用农杆菌介导法将大麦黄矮病毒GPV株系复制酶基因ORF1分别转化愈龄40d的幼胚愈伤组织,经过G418筛选后,共再生出15株抗性植株,拓宽了小麦农杆菌转化的受体基因型。PCR及Southern杂交分析证实大麦黄矮病毒复制酶基因ORF1已经整合到小麦基因组中,共获得14株转基因植株。抗病性初步检测结果显示,转基因植株对GPV株系具有抗性。研究结果还表明,对于不同的基因型小麦进行转化时,需选择适合本基因型的菌株。     

大麦黄矮病毒GPV株系ORF4基因在大肠杆菌中的表达及特异抗血清的制备

 根据已报道的大麦黄矮病毒GPV株系(BYDV-GPV)相关基因序列设计合成引物,利用RT-PCR方法获得ORF4基因,并将其克隆到原核表达载体pET-5a中。经IPTG诱导、SDS-PAGE分析,结果表明:ORF4基因在大肠杆菌BL21(DE3) pLysS中获得了高效表达,分子量为17 kDa。以回收的表达产物为抗原免疫家兔,制备了BYDV-GPV 17kDa蛋白的特异性抗血清。Western blot检测结果,制备的抗血清可用于检测BYDV-GPV侵染后在燕麦体内表达的17 kDa蛋白。     

New experimental hosts of Barley yellow dwarf virus among wild grasses,with implications for grassland habitats

Barley yellow dwarf virus (BYDV), an economically important virus, infects small grain cereal crops and over 150 other Poaceae species. BYDV infection plays an important role in competition among grasses in non‐managed systems, but many grasses remain unexamined as potential BYDV hosts. This study examined grass species that have not been reported as BYDV hosts but are commonly encountered in non‐managed grasslands throughout the United States and Canada. Laboratory inoculations with BYDV‐PAV using the aphid vector Rhopalosiphum padi were performed to examine the ability of 13 grass species and barley to be infected with the virus; eight of the grass species were not documented previously as virus hosts. Serological and molecular assays were used to confirm BYDV‐PAV infection. Plant height, number of leaves, number of tillers and weight were recorded to evaluate susceptibility or sensitivity to BYDV. Infection with BYDV was experimentally achieved for the first time on Achnatherum lettermanii, Achnatherum occidentale, Achnatherum thurberianum, Danthonia intermedia, Poa fendleriana, Sporobolus airoides and Sporobolus cryptandrus, but not on Alopecurus pratensis and Elymus wawawaiensis. Infection was confirmed in Bromus inermis, Elymus elymoides, Poa bulbosa, Poa secunda and Hordeum vulgare, which served as controls. BYDV infection caused reductions in plant height on P. bulbosa and P. fendleriana. BYDV‐infected P. secunda had more leaves per plant compared to healthy plants of the same species. BYDV‐infected A. lettermanii exhibited reduced dry weight in both below‐ground and above‐ground tissue. These findings have implications for the management and conservation of grassland habitats.     

大麦黄矮病毒-GAV在燕麦植株体内运动规律的初步研究

 利用RT-PCR方法研究了大麦黄矮病毒-GAV在燕麦植株内的移动规律。先将介体麦二叉蚜(Schizaphis graminum)在BYDV-GAV新鲜病叶上饲毒,再将获毒蚜虫放置到二叶期的健康燕麦植株接种48h,随后分期提取接种植株的第1~6片叶和根组织的总RNA,利用特异引物扩增BYDV-GAV的外壳蛋白(CP)基因以检测病毒在燕麦植株内的复制和移动。结果表明,在接种5d后,接种叶片(第2片叶)呈现阳性,接种7d后,植株新生的第4片叶被侵染,接种9d后,部分的第3片叶呈现阳性,至接种16d,几乎所有的叶片均呈现阳性。仅在接种的第5、7和9d收集的根组织呈现阳性,而所有的第1片叶均为阴性,可能是由于这些组织内病毒含量太低所致。本研究初步揭示了BYDV-GAV长距离运动的规律并且发现该病毒在燕麦根部从接种到系统发病都没有进行大量增殖,为今后进一步研究病毒运动机制选取适当的植物材料提供了基本信息。