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Artemisia sieberi showing symptoms resembling those caused by phytoplasma were observed in Geno Mountain, Hormozgan Province, Iran, and were examined for phytoplasma presence by PCR assays. In addition, the essential oils hydrodistilled from the aerial parts of phytoplasma-infected and healthy plants have been analyzed and compared by GC and GC/MS. Phylogenetic and virtual RFLP analysis of the 16S rRNA gene sequences revealed that the phytoplasma associated with A. sieberi witches' broom (AsWB) was a strain of 'Candidatus Phytoplasma aurantifolia'. The presence of the disease, however, induced a further enrichment (from 4.9 to 45.2%, a relative increase of 90%) of the entire monoterpene class as compared to the abundance in healthy samples. Conversely, a matching decrease in monoterpenoid (from 48.7 to 2%, a relative decrease of 90.2%) was observed in the infected plants. Besides the first report of phytoplasma infection of A. sieberi, the changes of its essential oils are reported.

In 2017 growing season numerous examinations of Cosmos bipinnatus in Hormozgan province, Iran revealed the disease symptoms similar to those associated with phytoplasmas. Phytoplasmas were detected from all symptomatic plants by the specific polymerase chain reaction (PCR) utilizing phytoplasma universal primer pairs. Amplification, sequencing and blast analysis of 16S rDNA fragment (ca. 1.2 kb) demonstrated that C. bipinnatus plants were infected by a phytoplasma belonging to the 16SrII group. This is the first report of association of a ‘Candidatus Phytoplasma aurantifolia’-related strain with C. bipinnatus phyllody in Iran.

Aerva javanica plants showing symptoms of witches’ broom, little leaf, and leaf roll were observed in 50% of the A. javanica plants grown in the deserts of Hormozgan province, Iran. This study was carried out to verify possible phytoplasma association with this disease, insect vector, and modification of the chemical composition of symptomatic A. javanica. Aerial parts were collected at the full flowering stage from symptomatic and asymptomatic plants and samples were examined for phytoplasma presence by nested-PCR assays. PCR and sequencing analysis showed that a phytoplasma was associated with the disease sharing 99% sequence identity with ‘Candidatus Phytoplasma aurantifolia’-related strains (16SrII). Furthermore, this phytoplasma was transmitted to healthy periwinkle plants under experimental conditions by the leafhopper Austroagallia sinuata that was then demonstrated to be a vector of this phytoplasma. Analysis of the oils carried out by GC–MS revealed the enrichment of the triterpene hydrocarbons (2.3% in asymptomatic vs. 11.8% in symptomatic samples) and the hydrocarbons (69.3% vs. 85.93%) as compared to the abundance in asymptomatic samples. Conversely, a matching decrease in ketone (3.51% vs. 0.6%) was observed in the symptomatic plants. These results indicate that phytoplasma presence is influencing the secondary metabolites production in infected plants.

Samples of Cota tinctoria with phytoplasma symptoms including witches’ broom, stunting, twisting of the shoots and little leaf were observed in Bandar Abbas, Iran, in 2017. Phylogenetic analysis revealed that the phytoplasma associated with Cota tinctoria witches’ broom (CtWB) is a strain of ‘Candidatus Phytoplasma trifolii’. Furthermore, the phytoplasma was successfully detected in the leafhopper, Orosius albicinctus collected from the symptom-bearing plants. This work therefore reports a new phytoplasma-associated disease on Cota tinctoria and its putative insect vector.

Zinnia elegans plants showing symptoms of phyllody, virescence, witches’ broom, little leaf and yellowing were observed in Bandar Abbas, Hormozgan Province, Iran. Analysis showed that the phytoplasma shares a 99% sequence identity with “Candidatus Phytoplasma aurantifolia” and is a strain related to this species. To the authors’ knowledge, this is the first report of the occurrence of a 16SrII phytoplasma infecting Zinnia elegans flowers.