Sterile explants were placed on agar-solidified MT medium (Murashige and Tucker, 1969) supplemented with 2.2 mg/L N6-benzyladenine, 1 mg/L indole-3- butyric acid and 3% sucrose. The pH was adjusted to 5.8 prior to autoclaving at 121ºC for 15 min. All explants were maintained at a temperature 24±2ºC under 16 h photopriod with light intensity of 3,000 lux.Plantlets were subcultured to fresh medium at intervals
of 4 to 8 weeks for 10 months dividing the shoots into 1-cm-long segments.
WBDL phytoplasma was detected using polymerase chain reaction (PCR). Total DNA was extracted from
leaves using cetyl trimethyl ammonium bromide
(CTAB) extraction method (Zhang et al., 1998). Two
primer pairs P3/P7 and P1/P7 were used to amplify
part of the 16S rRNA gene, the 16S–23S spacer region,
and a portion of the 5-end region of the 23S
rRNA gene from phytoplasmas.