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Keywords:

  • Phytoplasmas;
  • Aster yellows;
  • Clover phyllody;
  • PCR/RFLP;
  • Sequencing;
  • Ribosomal operon

Abstract

Lilium spp. with symptoms of severe fasciation were observed in Southern and central Bohemia during the period 1999–2003. Nucleic acids extracted from symptomatic and asymptomatic plants were used in nested-PCR assays with primers amplifying 16S–23S rRNA sequences specific for phytoplasmas. The subsequent nested-PCR with phytoplasma group-specific primers followed by RFLP analyses and the 16S ribosomal gene sequencing, allowed classification of the detected phytoplasmas in the aster yellows group, subgroups 16SrI-B and 16SrI-C alone, and in mixed infection. Samples infected by 16SrI-C phytoplasmas showed different overlapping RFLP profiles after Tru I digestion of R16F2/R2 amplicons. Two of these amplicons were sequenced, one of them directly and the other after cloning; sequence analyses and blast alignment confirmed the presence of two different overlapping patterns in samples studied. The sequences obtained were closely related, respectively, to operon A and operon B ribosomal sequences of the clover phyllody phytoplasma. Direct PCR followed by RFLP analyses of the tuf gene with two restriction enzymes showed no differences from reference strain of subgroup 16SrI-C. Infection with aster yellows phytoplasmas of 16SrI-B subgroup in asymptomatic lilies cv. Sunray was also detected.