Incidence of multiple and distinct species of caulimoviruses in dahlia (Dahlia variabilis)

Abstract

Dahlia mosaic is a serious disease affecting dahlias. In addition to the Dahlia mosaic virus (DMV) reported previously, we characterized two putative new caulimoviruses, tentatively designated as DMV-D10 and Dahlia common mosaic virus (DCMV), from dahlia. To better understand their relative incidence in dahlia, a total of 213 samples were collected during 2007 and 2008 from several varieties of cultivated dahlia (D. variabilis) in the United States. Samples were tested for the three caulimoviruses using virus-specific primers in a polymerase chain reaction. Amplicons were cloned and sequenced to confirm the infection of dahlia with these viruses. Results showed that DMV-D10 was the most prevalent (94%) followed by DCMV (48.5%) and DMV (23%). Mixed infections were common and viruses were detected irrespective of symptom expression at the time of sampling. Two percent of the samples were not infected by any of the three tested caulimoviruses. Results suggest that caulimovirus infections are widespread in dahlia and highlight the need for testing and production of virus-free material to reduce their spread.