Phloem limited bacteria: a threat to Khasi mandarin cultivation in Assam, India

Phloem limited bacteria i.e. phytoplasmas were detected in Khasi mandarin samples during a roving survey conducted for citrus greening disease (CDG) incidence in Assam and North East India. Dual infection of CGD and phytoplasmas was detected by molecular methods in the collected leaf samples. PCR amplification of the 16S rDNA of phytoplasmas yielded 1, 500 nucleotides product in direct PCR and 1, 250 nucleotides product in nested PCR assays, respectively, in some Khasi mandarin samples. All the CGD infected samples yielded a band of 703 base pair in Khasi mandarin samples. Identification and characterization of the detected phytoplasmas at molecular level, incidence and associated loss in yield together with the identification of the insect vector is a future research area.