Molecular characterization of phytoplasma of 16SrI-B group association with Acalypha indica in India.

The typical phytoplasma symptoms of little leaf, yellowing, chlorosis, witches' broom, and stunting growth were observed on Acalypha indica plants during the field survey conducted at Lucknow and surrounding districts in year 2015-2016. To confirm the association and possibility of phytoplasma etiology, PCR assays were performed using universal primer pairs (P1/P6) and nested primer pairs (R16F2n/R2) in a total of five diseased samples along with control. A ~1.2 Kb amplicon was observed in nested PCR assay in diseased sample; however, no band was observed in control sample. The positive amplicons were sequenced for 16S rDNA and used for the virtual RFLP analysis and phylogenetic studies. BLASTn search showed 99-100% sequence identities with the 'Candidatus phytoplasma asteris' members (16SrI group) and phylogenetic analysis showed closest relationship with member of 16SrI group. The virtual RFLP assigned it as a member of 16SrI-B subgroup. This is the first record of phytoplasma association of 'Ca. P. asteris' subgroup B with A. indica in the world.