Molecular identification of a ‘Candidatus Phytoplasma australasia’ strainin radish showing a little leaf disease in Andhra Pradesh, India

Abstract

Symptoms of little leaf, proliferation of axillary buds and pale green colour leaves were observed in radish plants grown in the farmer fields at Anantapuram, Andhra Pradesh. DNA was extracted from symptomatic and asymptomatic leaves and subjected to nested PCR assay with P1/P7 and R16F2n/R16R2 primers. The about 1,250 bp amplicon was obtained only from symptomatic radish plants and the positive control, but not from any asymptomatic plants. Pair wise sequence comparison and phylogenetic analyses of 16S rRNA gene sequences of the radish phytoplasma strain suggested that it is related to ‘Candidatus Phytoplasma australasia’. Further virtual RFLP analysis of 16S rDNA sequences allowed the classification of the radish phytoplasma strain in the 16SrII-D subgroup that results to be in great expansion in this area of India.