STRUCTURE AND EXPRESSION OF RNA GENOMES OF CLOSTEROVIRUSES

Literature data are summarized on the molecular biology, expression, a nd evolution of closteroviruses, a group of RNA-containing plant virus es possessing a number of unusual properties. Consideration is given t o the unique structure of closterovirus particles composed of two type s of structural protein (''rattlesnake'' structure), and comparative a nalysis is made for the closteroviral genomes sequenced recently. A hy pothesis is put forward for concerted evolution of large RNA genomes a nd viral replicases. The evolution of plant virus capsids and genomes is considered.