PCR detection of phytoplasmas from different tissues of root (wilt) diseased coconut palms

The suitability of various coconut palm tissues for a DNA-based detection of phytoplasmas associated with coconut root wilt disease in Kerala state, Southern India was determined. Four tissue sources were examined from adult palms displaying root (wilt) disease symptoms. Phytoplasma DNA was successfully amplified from nucleic acid samples extracted from inflorescence, spindle leaf, mature leaf and root tissues. The phytoplasma presence was verified in tissues from 12 affected palms sampled during the months of June, November and December of 2009, and from nine surviving palms in 2010 through nested PCR assay employing root (wilt) disease specific 16S rRNA gene primer pairs. Phytoplasmas were detected in 9 out of 12 palms from samples collected during the months of June 2009 and 2010. Phytoplasmas were most reliably found in spindle leaf (88.8%) and mature leaf (70.1%) samples and, to a lesser extent, in inflorescence (54.9%) or root (57.1%) samples.