Two types of virus like particles have been extracted from mycelium of Gaeumannomyces(Ophiobolus) graminis isolated from infected roots of wheat incities Yantai and Taian,Shandong Province.One is spherical to polyhedral 22-45 nm and predominal 27-32 nm in diameter,the other is rod-shaped about 16 nm in width and 40-108-185 nm in length with a broad central canal.The rod-shaped particles were seldom found in extract. The spherical virus particle preparation exhibited an ultraviolet absorption spectrum typical of nucleoprotein with λ maximum at 260 nm and λ minimum at 240 nm,A260/280=1.62,A260/240=1.24.When the spherical particles of Yantai or Taian isolates were placed in 0.8% agar immunodiffusion plates and tested against antiserum prepared with virus of Yantai isolate,specific precipitin lines appeared.The result indicated the same serotype between the two isolates. The dsRNA preparation extracted from virus of Yantai isolate had a maximum absorbance at 260 nm and minimum absorbance at 230 nm.When preparations were subjected to electrophoresis in 2.4% polyacrylamide agarose dis gel,two clear bands of closely similar mobility were obtained,thus showing that the Yantai isolate contained two genome and taxonomically belonged to the possible family i.e.isometric dsRNA mycoviruses requiring two RNA segments for replication.The virus contained mainly one capsid polypeptide with a molecular weight of 70,000 dalton. Extracts of 12 isolates collected from nine provinces(Zhejian,Hubei,Neimenggu,Heilongjiang,Jiangsu,Hebei,Shanxi,Shandong,Qinghai) were examined under the electron microscope,showing that all isolates contained spherical virus particles.The colony colourations,growth rates and virus concentration of all these isolates were observed.
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