Plant Disease Research

Phytoplasmas are prokaryotic wall less pathogens in the class mollicutes that inhabit plant phloem and insects. The inability of their isolation in-vitro, their low concentrations and uneven distributions make their detection difficult. Polymerase chain reaction (PCR) with primers from 16S rRNA of ribosomal protein sequence has simplified their identification and differentiation. Recent surveys showed a tremendous increase in phytopalsma like symptoms in different crops viz., big bud disease of tomato, little leaf of brinjal, phyllody of toria, sesame and Parthenium. In order to confirm the association of Phy toplasma with these diseases, nested PCR assay was designed using universal phytoplasma primers P1/P7 and R16F2n/R2 primers, respectively. The PCR product yielded 1.8kb from samples of toria and brinjal, but no amplification was seen in tomato and Parthenium samples. Nested PCR resulted in 1.2 kb amplification from all samples tested indicating the phytoplasma association; thus providing the quick and reliable diagnostic tool for detecting phytoplasma.