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A phytoplasma strain associated with pot marigold phyllody disease in Fars province of Iran was identified and characterized by molecular analyses and biological studies. Nested polymerase chain reaction using universal P1/P7 primer pair followed by R16F2n/R2, confirmed the presence of phytoplasmas in the symptomatic plants only, and in Psammotettix striatus leafhopper. BLAST search, phylogenetic analysis, and virtual RFLP patterns of cloned amplicons allowed to classify the pot marigold phyllody and P. striatus leafhopper phytoplasmas in the 16SrI-S subgroup. The phytoplasma was transmitted from infected pot marigold to periwinkle plants by dodder inducing symptoms typical of phytoplasma presence. P. striatus transmitted this phyllody phytoplasma to healthy pot marigold and periwinkle plants after its collection in the infected fields or after acquisition feeding on infected pot marigold plants under insect-proof greenhouse conditions. This is the first report of 16SrI-S phytoplasma associated with phyllody of pot marigold and of a phytoplasma of this ribosomal subgroup in Iran. [ABSTRACT FROM AUTHOR]

Phytoplasmas are important plant pathogens that affect crops, bushes, and trees. Wheat blue dwarf (WBD) phytoplasma is transmitted by the leafhopper Psammotettix striatus, with infection resulting in severe losses in wheat yield in Northwest China. Immunodominant membrane protein (Imp) potentially plays a crucial role in phytoplasma transmission, although the mechanisms of WBD phytoplasma transmission has not yet been elucidated. In this study, the interaction between α-tubulin and Imp was confirmed by a split-ubiquitin membrane yeast two-hybrid assay, and co-immunoprecipitation (co-IP) assay. Co-expression of mNeonGreen-Imp and mScarlet-α-tubulin fusion proteins in the baculovirus expression vector system (BEVS) showed that Imp colocalizes with α-tubulin in the cytoplasm of Spodoptera frugiperda (Sf9) cells near the cell membrane. Suppression of α-tubulin transcription by RNA interference (RNAi) decreased the transmission efficiency of the WBD phytoplasma. Results of this study show that Imp employs α-tubulin to promote transmission of WBD phytoplasma via leafhopper. To our knowledge, this is the first report that describes the molecular interactions between the WBD phytoplasma and leafhopper. These results may help elucidate the mechanisms governing transmission of phytoplasma by its insect vector and provide a candidate target gene for controlling spread of WBD phytoplasma in the field using the RNAi approach. [ABSTRACT FROM AUTHOR]