A severe disease induced by ‘Candidatus Phytoplasma asteris” in Digitalis lanata

In spring of 2007, a severe disease was observed in Digitalis lanata plants cultivated in an Herb Garden. Stunting of the whole plants, size reduction and reddish colour of leaf lamina, axillary bud proliferation (witches’ broom), virescence and rosetting of flower spikes were observed. ‘Candidatus Phytoplasma asteris’-related phytoplasmas were identified by direct and nested PCR assays followed by RFLP analyses on 16S ribosomal gene. RFLP analyses on rpL22, elongation factor EF-Tu, aminoacid kinase plus ribosome recycling factors and Amp genes showed that phytoplasmas infecting D. lanata are undistinguishable from representative phytoplasmas enclosed in ribosomal subgroup 16SrI-B. This is the first report of phytoplasma presence in this species.