Pathogenicity and Epidemic Risk of Barley Yellow Striate Mosaic Virus
[Objective]Barley yellow striate mosaic virus (BYSMV) is widely distributed in wheat producing areas of northern China.In order to evaluate the epidemic risk of the disease and provide a theoretical foundation for formulating strategies in prevention and control,the pathogenicity to gramineous crops was determined and its natural hosts were also identified.[Method]The virus was inoculated on 151 varieties of Triticum aestivum,Zea mays,Setaria italica,Sorghum bicolor,Avena sativa,and Hordeum vulgare by planthopper (Laodelphax striatellus) carrying BYSMV,and the uninoculated materials as control.The latent period and symptom progression of the virus on different hosts were observed and analyzed.After 30 d of inoculation,one-step RT-PCR was used to detect the infection of the virus.The pathogenicity of BYSMV to main hosts was analyzed by biological and molecular biological detection.A total of 580 suspected virus-infected samples were collected from gramineous crops growing area in Hebei Province,and BYSMV was detected using one-step RT-PCR to assess the risk of BYSMV epidemic in the field.[Result]After 9-10 d of inoculation with the virus,the leaves of T.aestivum,S.italica,H.vulgare and A.sativa showed chlorotic stripes,and the plants grew slowly and were seriously dwarfed.All tested varieties of these crops were susceptible to infection.The incidence of tested T.aestivum,S.italica,A.sativa and H.vulgare varieties was 60.00％-100％,18.18％-100％,55.56％-100％ and 100％,respectively.Yellow stripes and mild dwarfing symptoms could be observed after 15-17 d of virus inoculation on some Z.mays var.saccharata and S.bicolor.Among the tested Z.mays var.saccharata varieties,three varieties showed typical symptoms of BYSMV inoculation and the incidence was 14.29％-21.43％.Eight S.bicolor materials were susceptible to BYSMV with the incidence ranging from 4.00％ to 33.33％,but two of them remained asymptomatic.Field surveys revealed that the positive rate of BYSMV in T.aestivum,S.italica and Z.mays var.saccharata samples was 78.03％,100％ and 9.52％,respectively.The positive rate of BYSMV in Gramineae weeds,such as Setaria viridis,Eragrostis minor and Eleusine indica,was 75.68％,65.38％ and 8.33％,respectively.Artificial inoculation indicated that BYSMV could also infect Chloris virgata,Bromus japonica,Echinochloa crusgalli,Brachypodium distachyon and Avena fatua.The disease incidence was 100％,82.61％,20.00％,60.71％ and 10.00％,respectively.E.indica,E.crusgalli and A.fatua remained asymptomatic after being infected.[Conclusion]BYSMV has strong pathogenicity to T.aestivum,S.italica,H.vulgare and A.sativa.Cultivated varieties are susceptible to infection,it is necessary to focus on monitoring the epidemic dynamics of BYSMV to prevent major disasters.The pathogenicity of BYSMV to Z.mays var.saccharata and S.bicolor is relatively weak,and varies in different varieties.Resistant varieties can be selected for prevention and control.The weeds such as C.virgata,S.viridis,E.minor,E.indica are the primary initial infection of BYSMV,it is crucial to remove weeds to prevent the spread of BYSMV.
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