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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]

This study of potato leafhoppers population dynamics was conducted in Kerman province during 2005-2007. In this study Mahan, Bardsir and Lalehzar as the principal potato growing areas of Kerman province were selected. Sampling commenced at 40 days after planting on 8 June in Lalehzar region, 30 days after planting on 8 May in Bardsir and 55 days after planting on 4 May in Mahan. According to the results of this study 11 species belong to 11 genus; three families and six subfamilies were collected from three potato growing areas (Lalehzar, Bardsir, Mahan) during 2005-2007 and identified as follows: Empoasca decipiens, Psammotettix striatus, Unkanodes tanasijevici, Sogatella vibix, Exitianus fasciolatus, Euscelis alsius, Reptalus lindbergi, Pseudophlepsius binotatus, Circulifer sp., Macrosteles sp., Idiocerus sp. Statistical analysis revealed that Empoasca decipiens was the most abundant species in potato fields in Lalehzar, Bardsir and Mahan regions. [ABSTRACT FROM AUTHOR]

Wheat blue dwarf (WBD) is one of the most economically damaging cereal crop diseases in northwestern PR China. The agent associated with the WBD disease is a phytoplasma affiliated with the aster yellows (AY) group, subgroup C (16SrI-C). Since phytoplasma strains within the AY group are ecologically and genetically diverse, it has been conceived that the AY phytoplasma group may consist of more than one species. This communication presents evidence to demonstrate that, while each of the two 16 rRNA genes of the WBD phytoplasma shares >97.5 % sequence similarity with that of the ' Candidatus Phytoplasma asteris' reference strain, the WBD phytoplasma clearly represents an ecologically separated lineage: the WBD phytoplasma not only has its unique transmitting vector ( Psammotettix striatus ) but also elicits a distinctive symptom in its predominant plant host (wheat). In addition, the WBD phytoplasma possesses molecular characteristics that further manifest its significant divergence from ' Ca . P. asteris'. Such molecular characteristics include lineage-specific antigenic membrane proteins and a lower than 95 % genome-wide average nucleotide identity score with ' Ca . P. asteris'. These ecological, molecular and genomic evidences justify the recognition of the WBD phytoplasma as a novel taxon, ' Candidatus Phytoplasma tritici'.