Miroslav Glasa

Analysis of the viromes of three symptomatic Fabaceae plants, i.e., red clover (Trifolium pratense L.), pea (Pisum sativum L.), and common bean (Phaseolus vulgaris L.), using high-throughput sequencing revealed complex infections and enabled the acquisition of complete genomes of a potyvirus, bean yellow mosaic virus (BYMV). Based on phylogenetic analysis, the Slovak BYMV isolates belong to two distinct molecular groups, i.e., VI (isolate FA40) and XI (isolates DAT, PS2). Five commercial pea genotypes (Alderman, Ambrosia, Gloriosa, Herkules, Senator) were successfully infected with the BYMV-PS2 inoculum and displayed similar systemic chlorotic mottling symptoms. Relative comparison of optical density values using semi-quantitative DAS-ELISA revealed significant differences among virus titers in one of the infected pea genotypes (Ambrosia) when upper fully developed leaves were tested. Immunoblot analysis of systemically infected Alderman plants showed rather uneven virus accumulation in different plant parts. The lowest virus accumulation was repeatedly detected in the roots, while the highest was in the upper part of the plant stem.

Clematis vitalba L. is a climbing shrub and a pioneer plant in abandoned orchards or vineyards that are widespread in temperate climate zones. In past years, several viruses infecting the Clematis species have been identified, including different ilarviruses. Prunus virus I (PrVI) is a recently described ilarvirus, which has been shown to infect sweet cherries and peaches in Greece. Moreover, its presence has been detected in ornamental Clematis in Russia. In the present work, we analyzed the virome of wildly growing C. vitalba plants from Hungary, Slovakia and Croatia showing different kinds of symptoms using high-throughput sequencing (HTS) of small RNAs or ribodepleted RNAs. Applying HTS enabled us to identify the presence of PrVI in C. vitalba, and the bioinformatic analyses were further validated with RT-PCR using PrVI-specific primers and Sanger dideoxy sequencing. Nearly full genome sequences of all three viral RNAs of one Hungarian, two Slovak and one Croatian isolate were determined. Their phylogenetic analysis showed high similarity to each other and to other PrVI isolates described from Central Europe. As the sampled plants were co-infected with other viruses, it is not possible to determine a direct correlation between the infection with PrVI and the observed symptoms. Analyses of different Prunus species in stock collection showed infection of several peach and sweet cherry varieties in Hungary. Our results expand the knowledge on the natural host range of PrVI and highlight the necessity to evaluate alternative plant hosts (even non-Prunus) of PrVI and the role of the virus in the etiology of the potential diseases.