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Two of the most common leafhoppers present in Chile are the Cicadellidae Paratanus exitiosus and Bergallia valdiviana. They commonly occur in vineyards of central Chile, including some vineyards infected by phytoplasmas. The present study demonstrates that P. exitiosus and B. valdiviana can transmit 16SrIII-J phytoplasmas to grapevine and periwinkle plants. This provides improved understanding of the 16SrIII-J phytoplasma epidemiology in Chilean vineyards.

Symptoms of shoot and root malformation were observed in carrot plants in fields located in the North of Gran Canaria Island (Spain), during surveys carried out in spring 2015 and 2016. Total DNA extraction from the leaves of symptomatic plants was performed and PCR assays were carried out to detect the agents possibly associated to the observed symptoms. While ‘Candidatus Liberibacter solanacearum’ was detected in the majority of tested symptomatic samples, phytoplasmas belonging to the ribosomal group 16SrI were detected only in two samples. Phylogenetic analyses and sequencing, together with virtual RFLP, confirmed that ‘Ca. L. solanacearum’ strains detected in carrot samples belong to haplotype D.

Phytoplasmas are microorganisms associated with severe plant diseases affecting diverse agrarian activites worldwide. Since their discovery, conclusive proof of their pathogenicity is lacking due to failure to culture these organisms. This has also hindered studies on their biology, biochemistry and physiology, although significant taxonomic progress has been achieved from study of the 16S ribosomal gene and full genomic sequencing of four phytoplasma strains. The inability to fulfil Koch’s postulates severely restricts the understanding of the roles of these organisms in plant diseases and in plant/insect/phytoplasma interactions. Here we show that specific commercial media support axenic growth of phytoplasmas under defined conditions; the identity of the organisms was confirmed by PCR/RFLP analyses and sequencing of phytoplasma-specific genes. We have demonstrated for the first time that phytoplasmas, similarly to mycoplasmas, can grow independently from their host(s). This should assist reduction of the socio-economic impact of phytoplasma diseases worldwide through improved pathogen detection and consequently better management of the diseases they cause. Knowledge of mechanisms underlying the autonomous life of phytoplasmas, that are among the smallest living organisms, should also provide important information about basic mechanisms of life.