Detection and characterization of 16SrI-B phytoplasmas associated with yellow leaf disease of arecanut palm in India

During a survey on arecanut palms in Sullia district of Karnataka, yellowing of leaves and shedding of both mature and immature fruits were observed in June 2013. The disease association with phytoplasmas was confirmed using nested polymerase chain reaction with phytoplasma specific ribosomal primers, which amplified the 1 6S rRNA gene in leaves, roots and rachis tissues of symptomatic arecanut palms. BLAST analysis of ∼1.2kb sequence of amplicon from symptomatic leaf samples revealed 99% sequence identity with 16S rDNA sequences of ‘Candidatus Phytoplasma asteris’ (16SrI). Phylogenetic analysis based on 16S rDNA also confirmed the clustering of areacanut yellow leaf disease phytoplasma with members of 16SrI group. Real and virtual RFLP analysis suggested that the arecanut phytoplasmas in the present study belongs to 16SrI-B subgroup. The identification of 16SrI-B subgroup phytoplasma in yellow leaf disease of arecanut is the first report from India.