The spectrum of viruses isolated from Pulsatilla pratensis (Ranunculaceae) a native plant of Ukraine

Abstract

The article is devoted to virus screening of wild plants of Ukraine’s flora. The object of the research is the Red Book plant Pulsatilla pratensis (L.) Mill., which grows on the territory of Kanev Nature Reserve. Isolated isometric infectious virus-like particles with diameters of 34, 36, 43, 47, 50 and 57 nm were isolated from selected plants of P. pratensis. In our research, determination of the infectious nature of the pathogen, host range, concentration of viruses in plants, species identity and virus isolation from the mixture in mixed viral infections were carried with using indicator plants. The typical viral symptoms were observed on indicator plants: browning of the leaf plate, mottling, chlorosis and necrosis. All symptoms were systemic and could be caused by a variety of viruse species. Virions with sizes from 34 to 43 nm produced the necrotic and chlorotic spotting on Chenopodium amaranticolor Coste and Reyn. On the other hand, virions with sizes from 47 to 57 nm produced the necrosis, chlorosis and deformation of the leaf plates on Cucumis sativus L. That is not typical for viruses previously discovered on P. pratensis. The viruses isolated in these plants viruses were cumulated in small concentrations and rapidly lost their infectivity. The number of isolated viruses was insufficient for their identification. Four bacteriophage isolates with long phage tails of different size were isolated from P. pratensis roots and radical soil. The biological (lytic) activity towards the tracer bacteria, the morphology of negative colonies, and bacteriophage protein structure were characterized. According to our research, it is possible to divide phages into three subgroups that probably correspond to three different types of viruses. Results of the polypeptide analysis may reflect an evolutionary process in a population of phages that had a common ancestor. Comparison of phage proteins of different hosts shows a variety of molecular weights of polypeptides comprising up to several dozens of proteins. The results of the current work lay the basis for studying the spread of viruses in nature and determination of their relationships in biocenoses.

Keywords

• plant viruses
• bacteriophages
• electron microscopy