Identification of viral and phytoplasmal agents causing diseases in Gaillardia Foug. plants in Lithuania

Gaillardia plants exhibiting symptoms characteristic of viral and phytoplasmal diseases were collected at botanical gardens and floriculture farms in Lithuania. Cucumber mosaic cucumovirus was isolated from diseased plants exhibiting symptoms characterized by stunting, flower breaking and malformation of petals. The virus was characterized based on electron microscopy, serology, reactions of inoculated test-plants, and reverse transcription polymerase chain reaction (RT–PCR). Symptoms of leaf yellowing and general stunting of plants, and virescence and phyllody of flowers were associated with infection by a phytoplasma. Phytoplasmal 16S rRNA gene sequences were amplified in polymerase chain reactions (PCRs) primed by phytoplasma universal primer pairs P1/P7 and R16F2n/R16R2. RFLP analysis of the 1.2 kbp rDNA product, subjected to single enzyme digestions with nine restriction endonucleases, revealed that the Gaillardia plants were infected by a phytoplasma (gaillardia yellows, GaiY) belonging to group 16SrI (aster yellows phytoplasma group), subgroup I–C (clover phyllody, CPh, phytoplasma subgroup). 16S rDNA sequence alignments and phylogenetic analysis confirmed that the GaiY phytoplasma was closely related to CPh phytoplasma. Gaillardia can be naturally infected by a broad biodiversity of phytoplasma strains belonging to subgroups 16SrIII–B (clover yellow edge subgroup), 16SrI–A (aster yellows subgroup), and 16SrI–C in Lithuania.