Molecular identification of phytoplasmas from dill (Anethum graveolens L.; umbelliferae)

Dills (Anethum graveolens L.) grown from seeds in a small area of the Italian Riviera showed symptoms including stalk discoloration, flower virescence and phyllody. The affected plants were tested for the presence of phytoplasmas. DNAs were PCR-amplified in reactions with ribosomal universal or group-specific primer pairs and analysed by restriction digestions with BfaI or MseI enzyme. Phytoplasmas, identified as members of 16SrI-B, I-C, V-A and XII-A subgroups were present in 18 out of 22 samples (81.8%). Of these, 9 (50% of the infected) carried a single phytoplasma [3 subgroup 16SrI-B (16.6%), 1 16SrI-C (5.5%), and 5 16SrV-A (27.7%)]. Seven samples (38.8%) carried two different phytoplasmas (6 members of subgroups V-A and XII-A; I member of subgroups I-C and V-A). Two samples carried phytoplasmas of three different subgroups in different mixes (I-C, V-A and XII-A; I-B,I-C and XII-A). There was no clear correlation between a given symptom and the presence of one or more phytoplasmas. This is the first report from Europe of phytoplasmas in dill plants.