FIRST REPORT OF MIXED INFECTION OF PAPAYA RINGSPOT VIRUS AND PHYTOPLASMA IN PAPAYA IN INDIA
R. Verma, P. Gaikwad, D. Mungekar, S. Tripathi, V. Datar, J. Singh
Papaya plants exhibiting symptoms such as multiple axillary shoots, leaf reduction, mosaic, chlorosis, flattened petiole, oily spots on stem and virescence of flowers were observed in Pune (India). Electron microscopy observations of leaf dip preparations revealed flexuous filamentous particle of 760x12 nm, suggesting the presence of a potyvirus, which was identified as Papaya ringspot virus (PRSV) in ELISA using a specific antiserum. The presence of PRSV was confirmed by RT-PCR using coat protein gene-specific primers that amplified a fragment of ca. 950 bp in size. Sequence analysis of the RT-PCR product (GenBank accession No. KJ142142) showed 87 to 100% identity at the nucleotide level with other Indian PRSV isolates (Jain et al., 2004). The presence of a phytoplasma was tested in symptomatic papaya by PCR using universal P1/P7 and R16mF2/R16mR1 primer pairs. BLAST analysis of the consensus sequence obtained by sequencing PCR products (GenBank accession No. JQ346525) revealed 99% nucleotide sequence identity with Candidatus Phytoplasma aurantifolia, a member of group 16Sr II phytoplasma. Transmission of the phytoplasma to healthy papaya grafted onto infected papaya was obtained four weeks after grafting with the development of multiple axillary shoots. The presence of a phytoplasma and a virus in papaya has previously been reported in Puerto Rico and Cuba (Licha, 2002; Arocha et al., 2009). To our knowledge, this is the first evidence of mixed infection of PRSV and a phytoplasma in papaya from India, although these two pathogens were reported separately earlier (Jain et al., 2004; Rao et al., 2011).