First detection of Hydrangea ringspot virus in mountain hydrangea in the Czech Republic

Hydrangea is a very popular ornamental shrub in the Czech Republic and is often planted in private gardens and public areas. Unusual symptoms of conspicuous chlorotic rings and line patterns (from June to August), turning red-purple later in the season (from September to November), were observed on mountain hydrangea (Hydrangea serrata) in six different localities in Central Bohemia, East Bohemia and South Moravia in the Czech Republic between 2005 and 2007. The plants were found in private gardens, civic plantings, botanical gardens and nurseries.

Sap from symptomatic leaves was mechanically inoculated to plants of 11 herbaceous indicator species (Chenopodium amaranticolor, C. quinoa, Nicotiana tabacum cvs. Samsun and Xanthii, N. benthamiana, N. clevelandii ´ glutinosa, N. glutinosa, N. megalosiphon, N. rustica, and Petunia hybrida cvs. Slunicko and Nebeska Ruzicka). Clear symptoms appeared only on C. amaranticolor and C. quinoa, in the form of chlorotic local lesions which appeared within five days. Samples from both the original hydrangea plants and indicator plants with local lesions reacted positively in DAS-ELISA using antibodies to Hydrangea ringspot virus (HdRSV) (AS-0095; DSMZ, Germany). Filamentous particles, 490 nm long, were observed in indicator plants by transmission electron microscopy. The particles were decorated in immunosorbent electron microscopy according to Stein et al. (1986) using the same antibodies as in DAS-ELISA.

This is the first detection of HdRSV in mountain hydrangea, and the first report of the virus in the Czech Republic. The symptoms observed on mountain hydrangea differed significantly from those on bigleaf hydrangea (Hydrangea macrophylla) described by Koenig (1973).