Plants of sneezeweed (Helenium L.) exhibiting symptoms characteristic of diseases: viral (plant stunting, flower breaking) and phytoplasmal (general yellows, flower virescence, phyllody) were collected for investigation. The causal agent of viral disease, Tomato ringspot nepovirus, was isolated and identified by the methods of test-plants and electron microscopy. The causal agent of phytoplasmal disease was detected in polymerase chain reactions (PCRs) using phytoplasma universal primer pairs P1/P7 and R16F2n/R16R2. The 1.2 kbp 16S rDNA product was subjected to single enzyme digestions with 10 different restriction endonucleases. Restriction fragment length polymorphism (RFLP) analysis revealed that sneezeweed plants were infected by phytoplasma belonging to group 16SrI (aster yellows phytoplasma group), subgroup I-A, which type strain is tomato big bud phytoplasma.
Keywords: Helenium, virus, phytoplasma, identification.