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

Barley 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.     

RT-PCR-RFLP在大麦黄矮病毒检测中的应用

The universal primer of Luteovirus was designed and synthesized.An experimental system of RT PCR RFLP was developed in barley yellow dwarf virus (BYDVs).BYDVs can be distinguished qualitatively by RT PCR method.It was seen that different serotypes of BYDVs have critical different RFLP patters when the PCR producs were digested by restriction enzyme HinfI.The RFLP patterns of 7 isolates of PAV serotype were greatly different.These results indicate there existed sequence variations among different serotypes of BYDVs and vector phenotypes of PAV serotype.There is no difference between MAV serotypes in RFLP analysis.The slight distinction in the segment of coat protein gene of BYDVs can be revealed by RT PCR RFLP system.     

Barley Yellow Dwarf Luteovirus (BYDV) Infectivity of Alate Aphid Vectors in Northeast Spain

Rhopalosiphum padi and Sitobion avenae alates were collected from colonised winter cereals and maize in N.E. Spain and fed on young wheat plants for 7–10 days in the glasshouse. Then, aphids were killed and the plants on which aphids reproduced were kept in the glasshouse for 30–40 days. ELISA of infested plants was made using polyclonal and monoclonal antisera against PAV-, RPV- and MAV-like isolates. In autumn and spring, MAV serotypes were transmitted by S. avenae and R. padi , mainly in mixed infections with PAV serotypes. This possibly explains the high frequency of MAV-like isolates and their previously recorded year-to-year stability in maize, grain and forage winter cereals and cereal volunteers. PAV-like isolates were rarely transmitted by S. avenae and its spread thus depends almost exclusively on R. padi. These results confirm the importance of forage cereals and cereal volunteers as virus sources for winter cereal infection in the autumn, and the latter as a source of BYDV for maize in spring.     

Aphid Vectors of Barley Yellow Dwarf Virus in West-Central Morocco

The ability of seven aphid species, collected in west-central Morocco, to transmit barley yellow dwarf virus (BYDV) was determined. Aphids were either collected from grasses showing symptoms of BYDV infection or were allowed acquisition access to plants infected with a PAV-like isolate of BYDV before transfer to oat test plants. BYDV transmission by six of the seven aphid species was confirmed by ELISA test; only Melanaphis donacis failed to transmit. The six newly defined BYDV vector species brings the total known to occur in Morocco to ten.     

Screening for Barley Yellow Dwarf Luteovirus Resistance in Barley on the Basis of Virus Movement

The movement of barley yellow dwarf luteovirus (BYDV) was evaluated in susceptible and resistant barley and bread wheat genotypes. After leaf inoculation, the virus infected the root system and the growing point of susceptible earlier than resistant, barley genotypes. No difference in virus movement occurred in resistant and susceptible wheat genotypes. It was possible to reliably differentiate susceptible from resistant genotypes when root extracts of 41 barley genotypes were tested by DAS-ELISA 3 or 4 days after inoculation at the oneleaf stage. When barley plants inoculated at the two- or three-leaf stage were assayed by tissue-blot ELISA on nitrocellulose membrane, virus was detected in the phloem vessels of the growing points of the susceptible, but not of the resistant genotype, 4–6 days after inoculation. Our results thus suggest that screening for BYDV resistance in barley could be done quickly and cheaply especially when assays are made by the tissue-blot test.     

Identification, Distribution and Vector Population Dynamics of Barley Yellow Dwarf Virus in Three Cereal-Producing Areas of Spain

ELISA-based surveys during 1985–87 in three major cereal-growing areas of Spain confirmed the presence of barley yellow dwarf virus (BYDV). Samples of small grain cereals and grasses with and without BYDV-like symptoms were collected in the central, southwestern, and northeastern Spain. Infections were found in all cereal species sampled and in some grasses. About 37 % of the samples collected in 1985 were infacted with isolates of the PAV serotype. Isolates of the RPV serotype were less common, and were detected only in samples from the central region at El Encin, Madrid. Only a single sample, collected from El Encin in 1987, was unequivocally diagnosed as containing an isolate of the MAV serotype. Aphid vector population dynamics was monitored during fall and winter of 1984–87 in the central region. Rhopalosiphum padi L. appeared to be the most abundant species during fall and winter months, infesting grasses and volunteer wheat. Other species present were Sitobion avenae (F.), Metopolophium dirhodum (Walker) and Rhopalosiphum maidis (Fitch). Both R. padi and S. avenae seem to be anholocyclic in the central region of Spain, and are able to remain and reproduce on wheat volunteers and grasses until the beginning of spring. S, avenae populations increase quickly on wheat volunteers in April, while populations of R. padi remain low. Therefore, spread of S. avenae-transmitted BYDV types to neighbouring cereal fields seem more likely to occur than spread of other types. Other possible virus reservoirs, such as maize, also need investigation for a better understanding of BYDV epidemiology in the central and other cercal-growing areas of Spain.     

Barley Yellow Dwarf Virus Multiplication and Host Plant Tolerance in Durum Wheat

A Canadian PAV-like isolate of barley yellow dwarf virus (BYDV) was used to infect durum wheat (Triticum durum) cultivars previously identified in field trials involving artificial inoculation as highly sensitive (12 IDSN74), slightly tolerant (La Dulce), and relatively tolerant (Boohai and 12 IDSN227) to BYDV. The cultivars were inoculated in the greenhouse as seedlings, and indexed for virus accumulation by enzyme-linked immunosorbent assay (ELISA) at various intervals between 3 and 60 days thereafter. Mean ELISA values were somewhat consistent with tolerance levels for 4 durum wheat cultivars, but the use of ELISA to screen for BYDV resistance in durum wheat is not practical. The magnitude of the difference between sensitive and tolerant cultivars for the mean ELISA value is not high enough, and it may be necessary to average readings between 3 and 60 days after inoculation to obtain somewhat meaningful ELISA data. The effect of vector aphid numbers on virus titre and aerial biomass in the sensitive durum wheat cv. Karim was also evaluated. There was no significant effect on virus content in a preliminary trial, but a second trial revealed that more viruliferous aphids per plant resulted in higher ELISA values. Infestation with 32 or 50 viruliferous Rhopalosiphum padi per plant depressed biomass yield below the level observed with 1–10 aphids per plant.     

大麦黄矮病毒运动蛋白是RNA沉默抑制因子

大麦黄矮病毒(barley yellow dwarf virus,BYDV)属黄症病毒科家族,其基因组包含6个开放阅读框(open reading frames,ORFs).将BYDV的6个基因分别克隆到pWEIMING101载体上,得到重组基因.电击转化农杆菌后,利用农杆菌瞬时表达方法渗透注射转GFP基因的本氏烟草16c植株的叶片,在长波长紫外灯下观察GFP的表达,并通过Northern blot证明所得现象.研究结果表明,BYDV的PAV株系ORF4编码的运动蛋白(movement protein,MP)是RNA沉默抑制因子,其表达可以抑制局部和系统RNA沉默.BYDV-MP与GFP的双链RNA(dsGFP)共表达后仍能抑制RNA沉默,荧光强度与叶片中GFP的mRNA和其沉默降解形成的siRNA的量有对应关系,其N端核定位序列对抑制局部基因沉默起主要作用,第5、6位氨基酸是抑制基因沉默的关键氨基酸.BYDV-MP单独渗透注射的部位均产生细胞死亡.     

Brome Mosaic Virus Infection Mimics, Barley Yellow Dwarf Virus Disease Symptoms in Small Grains

Previous studies on the occurrence of “barley yellow dwarf virus (BYDV) disease” in South Africa have led to the conclusion that, although this virus is present, the main causative agent of “yellow dwarf” disease in cereals appears to be the unrelated brome mosaic virus (BMV). In this study, material from South Africa, Britain and Australia that had been identified symprtomatically as being infected with BYDV, was found by serological testing to contain BMV. No BYDV could be detected in the same samples. This report discusses the hazards of relying on symptom expression for the diagnosis of a common world-wide disease problem.     

Growth Regulators and the Effect of Barley Yellow Dwarf Virus on Barley (Hordeum vulgare L.)

Estimation of cell number in the third leaf of barley (Hordeumvulgare L. C I 666) infected with barley yellow dwarf virus(BYDV) showed a marked decrease in the mitotic activity of theinfected plants Assay of endogenous gibberellins revealed adecrease in the level of a substance corresponding to gibberellicacid (GA₃) in BYDV-infected plants No significant differencein the level of endogenous auxins was observed Application ofgibberellic acid to infected plants reversed the dwarfing effectbut the response was not significantly different from the responseof healthy plants and was found to be due to increased cellelongation. It is suggested that the dwarfing of BYDV-infectedplants is a result of reduced mitotic activity This may be relatedto the reduced level of endogenous gibberellins.     

Reactions in Maize Infected with Swedish Isolates of Barley Yellow Dwarf (BYDV)

Nine cultivars of maize (Zea mays L.) were tested for susceptibility to BYDV under three temperature ranges in the greenhouse. Three Swedish isolates of BYDV were used, two specifically transmitted by Rhopalosiphum padi (L.) (39/78) and by Sitobion avenae (Fabr.) (27/77), respectively, and the third by both species (70). The virus isolates were transmitted successfully from different grasses to maize and from infected maize to the susceptible oat cultivar "Sol II" by the respective aphid species. S. avenae showed very high ability to transmit the S. avenae specific isolate to and from maize plants.
The main symptoms that developed on maize were fine chlorotic irregular spots, reddish purple discoloration and malformed leaves.
The relationship between maize cultivar, temperature and percent of infection is discussed. Enzyme-linked Immunosorbent Assay (ELISA) was used with success to detect the virus isolate 27/77 in susceptible and symptomless maize plants.
Electron microscopy of maize (cv. LG ll) infected with the 27/77 isolate of BYDV revealed virus-like particles, about 22 nm in diameter, in the nuclei of companion cells, in the plasmodesmata connecting companion cells with mature sieve tubes, in the lumen of mature sieve tubes and in xylem tracheal elements.     

Tripartite Interactions of Barley Yellow Dwarf Virus,Sitobion avenae and Wheat Varieties

The tripartite interactions in a pathosystem involving wheat (Triticum aestivum L.), the Barley yellow dwarf virus (BYDV), and the BYDV vector aphid Sitobion avenae were studied under field conditions to determine the impact of these interactions on aphid populations, virus pathology and grain yield. Wheat varietal resistance to BYDV and aphids varied among the three wheat varieties studied over two consecutive years. The results demonstrated that (1) aphid peak number (APN) in the aphid + BYDV (viruliferous aphid) treatment was greater and occurred earlier than that in the non-viruliferous aphid treatment. The APN and the area under the curve of population dynamics (AUC) on a S. avenae-resistant variety 98-10-30 was significantly lower than on two aphid-susceptible varieties Tam200(13)G and Xiaoyan6. (2) The production of alatae (PA) was greater on the variety 98-10-30 than on the other varieties, and PA was greater in the aphid + BYDV treatment on 98-10-30 than in the non-viruliferous aphid treatment, but this trend was reversed on Tam200(13)G and Xiaoyan6. (3) The BYDV disease incidence (DIC) on the variety 98-10-30 was greater than that on the other two varieties in 2012, and the disease index (DID) on Tam200(13)G was lower than on the other varieties in the aphid + BYDV and BYDV treatments in 2012, but not in 2011 when aphid vector numbers were generally lower. (4) Yield loss in the aphid + BYDV treatment tended to be greater than that in the aphid or BYDV alone treatments across varieties and years. We suggested that aphid population development and BYDV transmission tend to promote each other under field conditions. The aphids + BYDV treatment caused greater yield reductions than non-viruliferous aphids or virus treatment. Wheat varietal resistance in 98-10-30 affects the aphid dispersal, virus transmission and wheat yield loss though inhibits aphid populations from increasing.     

A conspectus of Barley Yellow Dwarf in Pakistan

Wheat is an important cereal crop worldwide and in Pakistan. Among the wheat producing countries, Pakistan ranks 6th with an annual wheat production of 24.214 million tons. Burgeoning population of the country demands increase in its production that is hindered by a number of pests, pathogens and environmental stresses. Among the yield limiting constraints, Barley Yellow Dwarf Virus (BYDV) is important, inflicting approximately 75% wheat production losses in diseased crop nationally. Research on BYDV and its management is mandatory for sustainable agriculture in the country. This review focuses on BYDV, its relationship with vectors, classification and management practices. Additionally, its currents status in Pakistan has been reviewed.     

玉米矮花叶病毒研究进展

玉米矮花叶病毒 (Maizedwarfmosaicvirus,MDMV)是在世界范围内广泛分布的重要病毒 ,文中从寄主范围、传播、株系状况、分子生物学及检测等方面 ,对MDMV的国内外研究现状进行了阐述。     

Differential Interaction Between PAV-like Isolates of Barley Yellow Dwarf Virus and Barley (Hordeum vulgare L.) genotypes

Four PAV-like isolates of barley yellow dwarf virus (BYDV) were identified as causing very severe (RG), severe (2t), moderately severe (3b) and mild symptoms (13t) in barley (Hordeum vulgare) cultivar Plaisant in a growth chamber at 25 days after inoculation. These isolates had different effects on a range of barley genotypes. Cultivar Vixen, which contains the Yd2 resistance gene, and 80-81 BQCB10 were not affected by any isolate. Five other genotypes were significantly affected by at, least one of the isolates. Line Ea52 (which is a mutant of the Japanese cultivar Chikurine Ibaraki) was more susceptible to BYDV-PAV than Chikurin Ibaraki 1. No serological differences were detected between the four isolates using monoclonal or polyclonal antibodies. Virus antigen concentration, estimated by enzyme-linked immunosorbent assay (ELISA), was correlated with the decrease in the shoot fresh weight for all isolates and all genotypes except for Vixen and 80-81BQCB10. In field tests, the severity of symptoms induced by the BYDV-PAV isolates was in accordance with that estimated in the growth chamber. However isolate 2t was more severe on cultivar Vixen and overcame the partial resistance of Chikurin Ibaraki 1 to the three other isolates. The results show that virus antigen concentration not only contributes to characterizing the resistance levels of barley genotypes but also the severity of BYDV-PAV isolates.     

Differential Interaction Between PAV-like Isolates of Barley Yellow Dwarf Virus and Barley (Hordeum vulgare L.) genotypes

Four PAV-like isolates of barley yellow dwarf virus (BYDV) were identified as causing very severe (RG), severe (2t), moderately severe (3b) and mild symptoms (13t) in barley (Hordeum vulgare) cultivar Plaisant in a growth chamber at 25 days after inoculation. These isolates had different effects on a range of barley genotypes. Cultivar Vixen, which contains the Yd2 resistance gene, and 80–81BQCB10 were not affected by any isolate. Five other genotypes were significantly affected by at least one of the isolates. Line Ea52 (which is a mutant of the Japanese cultivar Chikurine Ibaraki) was more susceptible to BYDV-PAV than Chikurin Ibaraki 1. No serological differences were detected between the four isolates using monoclonal or polyclonal antibodies. Virus antigen concentration, estimated by enzyme-linked immunosorbent assay (ELISA), was correlated with the decrease in the shoot fresh weight for all isolates and all genotypes except for Vixen and 80–81BQCB10. In field tests, the severity of symptoms induced by the BYDV-PAV isolates was in accordance with that estimated in the growth chamber. However isolate 2t was more severe on cultivar Vixen and overcame the partial resistance of Chikurin Ibaraki 1 to the three other isolates. The results show that virus antigen concentration not only contributes to characterizing the resistance levels of barley genotypes but also the severity of BYDV-PAV isolates.