Molecular Identification of Phytoplasmas Infecting Diseased Pine Trees in the UNESCO-Protected Curonian Spit of Lithuania

A large-scale infection of pine trees by phytoplasmas, particularly Candidatus (Ca.) Phytoplasma pini-related strains, has been documented for the first time in Lithuania. This discovery challenges the conventional understanding that phytoplasmas primarily affect angiosperms and expands their known host range to include coniferous plants like Scots pine (Pinus sylvestris) and mountain pine (Pinus mugo). The study, conducted between 2008–2014 in the UNESCO-Protected Curonian Spit and Southern Lithuania, identified phytoplasma infections in nearly 300 trees, with 80% testing positive. Molecular analysis using RFLP and nucleotide sequencing of the 16S rRNA gene revealed that 98% of infected samples belonged to Ca. Phytoplasma pini-related strains (subgroup 16SrXXI-A), while a small fraction were associated with Ca. Phytoplasma asteris-related strains (subgroup 16SrI-A). This is the first report of subgroup 16SrI-A in pine trees, highlighting its potential broader geographic distribution and ecological impact on coniferous forests.

Valiunas, D., Jomantiene, R., Ivanauskas, A., Urbonaite, I., Sneideris, D., & Davis, R. (2015). Molecular Identification of Phytoplasmas Infecting Diseased Pine Trees in the UNESCO-Protected Curonian Spit of Lithuania. Forests, 6(7), 2469–2483. https://doi.org/10.3390/f6072469