Molecular Detection of a Phytoplasma Associated with Witches’ Broom in South India
Stachytarpheta (Stachytarpheta jamaicensis L.) plants showing typical symptoms of infection by a phytoplasma that causes whitche's broom disease were commonly observed in recent years in parts of south India. The symptoms included excessive production of spikelets in an upright fashion within inflorescence axis, bearing pedicelled phylloid flowers, carpels transformed into a pair of folded upright leafy structures followed by extensive proliferation of side shoots. The causal agent of the witches’ broom disease was identified based on symptoms, fluorescent microscopy, amplification of 16S rDNA of the phytoplasma by polymerase chain reaction (PCR) from infected samples. Standard PCR and nested-PCR (N-PCR) protocols were developed for improved efficiency and reliability of the diagnostic protocols. Using the primers P1/P7 and R16F2n/R16R2 primers, 1800 bp and 1200 bp size products were amplified in standard PCR and N-PCR protocols, respectively. The molecular identification of this new disease has been discussed.