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During January 2010, severe stunting symptoms were observed in clonally propagated oil palm (Elaeis guineensis Jacq.) in West Godavari district, Andhra Pradesh, India. Leaf samples of symptomatic oil palms were collected, and the presence of phytoplasma was confirmed by nested polymerase chain reaction (PCR) using universal phytoplasma-specific primer pairs P1 ⁄ P7 followed by R16F2n ⁄ R16R2 for amplification of the 16S rRNA gene and semi-nested PCR using universal phytoplasma-specific primer pairs SecAfor1 ⁄ SecArev3 followed by SecAfor2 ⁄ SecArev3 for amplification of a part of the secA gene. Sequencing and BLAST analysis of the 1.25 kb and 480 bp of 16S rDNA and secA gene fragments indicated that the phytoplasma associated with oil palm stunting (OPS) disease was identical to 16SrI aster yellows group phytoplasma. Further characterization of the phytoplasma by in silico restriction enzyme digestion of 16S rDNA and virtual gel plotting of sequenced 16S rDNA of 1.25 kb using iPhyClassifier online tool indicated that OPS phytoplasma is a member of 16SrI-B subgroup and is a ÔCandidatus Phytoplasma asterisÕ-related strain. Phylogenetic analysis of 16S rDNA and secA of OPS phytoplasma also grouped it with 16SrI-B. This is the first report of association of phytoplasma of the 16SrI-B subgroup phytoplasma with oil palm in the world.

Samples from toria plants (Brassica rapa L. subsp. dichotoma (Roxb.)) exhibiting phyllody, virescence, witches broom, extensive malformation of floral parts, formation of bladder like siliquae and flower sterility were collected from four different locations in India. Sequencing and phylogenetic analysis of the 16S rRNA, a part of 23S rRNA, partial sec A genes, rp gene and 16S-23S intergenic spacer region indicated that the phytoplasmas associated with toria phyllody (TP) symptoms were identical and belonged to 16SrIX phytoplasma Pigeon pea witches'-broom (PPWB) group. The iPhyClassifier generated virtual RFLP pattern of 1.25 kb 16S rDNA sequences indicated that TP phytoplasma belongs to 16SrIX-C phytoplasma subgroup. Complete 23S rRNA gene of TP phytoplasma had 2,787 nucleotides and is the first sequence of 16SrIX phytoplasma group. Restriction digestion of 16S rDNA and 23S rDNA PCR products has also shown that TP phytoplasmas from all the four locations in India were identical. Toria is a previously unreported host for a phytoplasma in16SrIX-C subgroup.

Citrus Decline Disease was recently reported to affect several citrus species in Iran when grafted on a local rootstock variety, Bakraee. Preliminary studies found “Candidatus Phytoplasma aurantifoliae” and “Candidatus Liberibacter asiaticus” as putative etiological agents, but were not ultimately able to determine which one, or if an association of both, were causing the disease. The current study has the aim of characterizing the microbiota of citrus plants that are either asymptomatic, showing early symptoms, or showing late symptoms through amplification of the V1–V3 region of 16S rRNA gene using an Illumina sequencer in order to (i) clarify the etiology of the disease, and (ii) describe the microbiota associated to different symptom stages. Our results suggest that liberibacter may be the main pathogen causing Citrus Decline Disease, but cannot rule out the possibility of phytoplasma being involved as well. The characterization of microbiota shows that the leaves show only two kinds of communities, either symptomatic or asymptomatic, while roots show clear distinction between early and late symptoms. These results could lead to the identification of bacteria that are related to successful plant defense response and, therefore, to immunity to the Citrus Decline Disease.

Phyllody disease associated with 16SrIX phytoplasma was observed in the range of 4.1-11% in 10 different lines of toria [Brassica rapa L. subsp. dichotoma (Roxb.)] in experimental fields of the Indian Agricultural Research Institute, New Delhi, India during 2008 and 2009.The toria phyllody (TP) phytoplasma was detected in all the symptomatic and 13.3% of asymptomatic toria plants by nested PCR. The phytoplasma was detected in midrib, flower part, siliquae, stem, and root of infected plants as well as seeds. TP was transmitted by grafting and by dodder to toria and nine other rapeseed/mustard species as confirmed by nested PCR. However, symptoms of phytoplasma infection were induced only in toria, yellow sarson [Brassica rapa L. subsp. trilocularis (Roxb.)], brown sarson [Brassica rapa L. subsp. sarson (Prain)], rapeseed (B. napus subsp. oleifera), and rocket or taramira (Eruca sativa) but not in mustard (B. juncea), black mustard (B. nigra), Ethiopian mustard (B. carinata), B. tournefortii and white mustard (Sinapis alba). Transmission of TP phytoplasma to periwinkle (Catharanthus roseus) was successful only through dodder, but no transmission to tomato (Lycopersicon esculentum) or brinjal (Solanum melongena) was found. TP phytoplasma was detected in Laodelpax striatellus, an abundant planthopper in toria fields, which indicates that this planthopper may be a potential vector for TP phytoplasma.

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