Culture medium. The medium used was the Gamborg B5
medium, gelled with 2.8g/L Gelrite and 30% sucrose as carbon
source. The pH was adjusted to 5.7 -5.8 with 1N KOH
or 0.1N HCl prior to autoclaving. Tetracycline at 15 mg/L
and 2 ml/L Plant Preservative Mixture (PPM) were added
to the medium to check the contamination. Trimmed buds
were inoculated onto the medium and the cultures wer