The need to study plant viruses in the Russian Far East is chiefly determined by the fact that its southern region, Primorye Territory, is an area of intensive farming. Their comprehensive examination would help lessen crop losses caused by numerous pests and plant diseases, including viral ones.
    Systematic study of viruses and virus-caused diseases on cultured and wild Primorye flora were begun in 1962 under V. G. Reifman, Cand. Sci. (Agriculture). Since then, our group of phytovirologists was reorganized into three laboratories that study the specific composition of viruses, their distribution and ill effects, ecological role in human activity and virus-specific proteins and RNAs, as well as the pathways and methods of virus distribution and transmitter-insects (aphids, cicadas, 28-spot bug) to elucidate the basic regularities of virus effects on metabolism of diseased plants by successfully using the method of isolated protoplasts in examining the  penetration of viruses into and reproduction thereof in cells. For the first time in Primoryes plant growing practice, immunodiagnostic methods were introduced involving antiviral sera allowing to select virus-free material to significantly speed up selection of virus-resistant potato, soya, vegetable and cereal varieties.
    Basic and applied studies involved biological testing, electron microscopy, peptide mapping, methods of immunochemical analysis ranging from classical techniques to new-generation methods, viz. immunoenzymic analysis, rocket immunoelectrophoresis, immunobloating, etc., electrophoresis of virus-specific proteins, methods of purifying viruses and their strains, obtainment of rabbit antiviral antibodies, etc.
    Monitoring of basic potato diseases in Primorye allowed to identify eleven virus, one micoplasma (purple curling of potato upper leaves) and viroid (spool-like potato tuber) disease.
    Soya, the most widespread among leguminous plants in Primorye, was used to study the most widespread and harmful (affecting from 50 to 70% of plants) Soya mosaic virus, which inflicts greatest economic damage and occurs in three strains. With regard to virulence and pathogenicity, we scrutinized weak-, strong- and medium-pathogenic strains of that virus, compared their characteristics in infecting Russian, Japanese and Chinese varieties. Ten viruses were identified in Primorye on leguminous plants, including three new ones on soya, viz. weak mosaic virus, chlorotic spottiness and chlorotic leaf deformation virus.
    Cereals were used to study the Far Eastern strain of the northern cereal mosaic virus and the biology of its sole transmitter, the dark cicada. Other widespread viruses affecting cereals in Primorye are the brome grass mosaic and striped barley mosaic viruses.
    Vegetable crops were used to reveal various strains of tobacco and common mosaic viruses. Discovered among them were strongly pathogenic strains inflicting major economic damage to crop.
    A study of the specific composition of plant viruses is necessary not only to select stable varieties for Primoryes plant growing, but also to forecast epiphytes and develop preventive measures to protect plants against viruses causing tangible losses.
    Apart from its applied significance, the study of plant viruses adds to our knowledge of basic issues of virology, since it helps reveal new viruses and their strains, describe the properties of new and already familiar viruses morphologically, with regard to their host plants and the physical and physicochemical and antigen characteristics of viral proteins, and specify the taxonomic position of viruses identified in Primorye.
    Quite profound studies are conducted in Primorye to scrutinize the antigen structure and functions of capsid proteins as antigens. As a matter of fact, the Institute of Biology and Soil Science is the only academic institution in Russia engaged in relevant research.
    We studied basic regularities in obtaining polyclonal antibodies to surface virion proteins and clarified the mechanism of polyclonal antibody production in various animal species (rabbits, mice, chicken) under the impact of non-specific immunogenetic factors (immunization, dosage, reimmunization, and impact of adjuvants, including those of Primorye origin).
    We have also improved and developed optimal conditions of classical and recent methods of identifying virus proteins.
    For all the viruses examined, we developed new-generation immunodiagnostic methods for imuunophysical analysis and methods for their immunodiagnostics. The study of antigen interrelations between viruses and their strains by modern methods of quantitative immunochemistry together with results of biological testing and physicochemical characteristics of capsid proteins and RNA serve as reliable criteria in determining the taxonomy of viruses and their strains in accord with recent classification.
    With the aid of non-immunologic methods of indirect polymerase chain reaction and DNA-peroxidase probes, we revealed viral RNAs, and by means  of electrophoresis of the viroid RNA the spool-like form of potato tubers.
    Today, we have identified approximately seventy crop-affecting viruses and their strains in Primorye to assign them to specific families and species.
    In examining further prospects of phytovirological studies in Primorye, we would like to identify four major tasks involving: (a) identification and characterization of new pathogens and their strains; (b) creation of new approaches to identifying vurus=specific proteins and RNAs and immunization schemes; (c) introduction of highly sensitive and specific new-generation immunization techniques; (d) introduction of high-sensitivity new-generation techniques for diagnosing antigens and antibodies, and development of measures for integrated protection of agricultural plants in Primorye against viral diseases.
 

LEGENDS TO FIGURES:

Dr. R..Gnutova , Institute of Biology and Soil Science, F. E. Branch, Russian Academy of Sciences.
  
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