First report of 'Candidatus Phytoplasma aurantifolia'(16SrII-A) associated with strawflower phyllody

Four strawflower plant samples showing phyllody disease symptoms were collected from the experimental plot at the College of Horticulture, Bangalore, Karnataka (India). The phytoplasma infection in strawflower was confirmed through PCR using 16Sr RNA and SecY gene specific primers. All four strawflower plant samples gave positive amplification 16Sr RNA (1.8 kb) and SecY gene (1.6 kb) for the phytoplasma. The amplified products were cloned and sequenced. The sequences of four clones obtained were identical. Therefore, a representative isolate (SWF1) nucleotide (nt) sequence of 16Sr RNA and SecY gene comparisons were made with the available phytoplasmas 16Sr RNA and SecY gene nt sequences from NCBI database. The analysis showed that strawflower phyllody phytoplasma shared the highest identity of 97.3 to 98.5% (16S rRNA) and 99.4 to 99.5% (SecY gene) with 'Candidatus Phytoplasma aurantifolia' group (16SrII) isolates reported from different parts of the world. This was well supported by close clustering of strawflower phytoplasma in the current study with 'Ca. P. aurantifolia' 16SrII groups in the phylogenetic analysis. The virtual RFLP pattern generated for the phytoplasma from strawflower phyllody was similar (similarity coefficient 0.97) to the reference pattern of 16Sr group II and subgroup A ('Ca.P. aurantifolia', 16SrII). This is the first report of phytoplasma associated with the phyllody disease of strawflower in India.