Molecular characterization of diverse phytoplasmas of subgroups 16SrI‐A, 16SrI‐B, 16SrI‐L, and 16SrI‐M infecting ornamental plants in Lithuania

Trade in ornamental plant species comprises a significant segment in the economies of countries in Europe, North America and Asia. Since the quality of ornamental plants is adversely affected by diseases attributed to phytoplasmas, we surveyed plant collections in botanical gardens and floriculture farms in Lithuania for phytoplasmal diseases. Seventeen ornamental species belonging to nine plant families exhibited disease symptoms including general yellowing and stunting, proliferation of shoots, phyllody, virescence and reduced size of flowers, and reddening of leaves. Analysis of the phytoplasmal 16S rRNA gene sequences amplified by PCR revealed that the plants were infected by phytoplasmas belonging to four distinct subgroups (16SrI‐A, 16SrI‐B, 16SrI‐L, and 16SrI‐M) of group 16SrI (aster yellows phytoplasma group) and indicated the presence of sequence‐heterogeneous 16S rRNA genes in newly recognized strains belonging to subgroups 16Sr‐L and 16SrI‐M. Infections by these diverse phytoplasmas in a wide array of plant species and families suggests that unidentified, polyphagous insect vectors may actively transmit phytoplasmas threatening the Baltic region's ornamental plant industry.