Phytoplasma transmission by seed

The transmission of phytoplasmas by seed was reported in several herbaceous and some woody plant species. The seedlings were usually analyzed for the presence of phytoplasmas in different stages of growth by nested-PCR/RFLP analysis and phytoplasmas belonging to different ribosomal groups according with species and geographical distribution were detected. The phytoplasma isolation from corn seedlings confirms the seed transmission of viable phytoplasma cells. The sudden epidemic events associated with the presence of phytoplasmas molecularly undistinguishable, in very distant geographic areas, on the same herbaceous species, provides further indications of transmission of these prokaryotes also by seeds. In all the analysed species, the phytoplasma detected in seedlings belong to different ribosomal groups, in some cases they are found also in mixed infection. Since phytoplasma presence is not contemplated in propagation material by the any of the worldwide plant protection quarantine protocols nor by seed producers, the movement of seeds from infected plants implies a wide dissemination of the pathogens and therefore of the associated diseases in still uncontaminated areas.