A chrysanthemum decline associated with phytoplasma presence in italy

The chrysanthemum is a popular ornamental flower all around the world for both cut flowers and potted plants. In recent days, bacterial infections are reducing in several cases its market value. Irregular flowering, yellowing and decline symptoms were observed at a commercial enterprise located in North Italy. To verify the presence of phytoplasmas, DNA was extracted from symptomatic and asymptomatic potted plants and subjected to specific polymerase chain reaction followed by restriction fragment length polymorphism analysis on phytoplasma 16S ribosomal gene. The tests were carried out three times in 7 months to verify the persistence of detected phytoplasmas over time. Phytoplasma classified in group 16SrV (elm yellows) were detected in all the examined samples independently from the presence of decline symptoms, while group 16SrXII (“stolbur”) phytoplasmas were only detected in the most severely declining plants. This latter phytoplasma strain was also characterized on tuf and leu genes by RFLP analyses and sequencing, respectively, to cross confirm its presence and identity. The detection of this phytoplasma in chrysanthemum plants is the first report in Italy, while it has already been identified in plants with malformed inflorescence in Europe, but not in other parts of the world.