Abstract:
In this study petiole explants were obtained from in vitro grown diploid E. p u rp u re a (Purple coneflower: Asteraceae)
plantlets and shoots were regenerated by culturing the explants on MS basal medium containing 0.3 mg/1 BA, 0.01
mg/1 NAA and four different concentrations (30, 60, 120 and 240 mg/1) of colchicine for 30 days or 120 mg/1 of
colchicine for various durations (7 ,1 4 , 21, and 28 days). The regenerated shoots were induced to root on MS basal
medium with 0.01 mg/1 NAA, then the root-tips of the regenerated shoots were sampled and the chromosome number
of the root tip cells was counted. Completely Randomized Design (CRD) was used with 5 replicates. It was found that a
treating duration longer than seven days was necessary for the induction of tetraploid shoots, and treating the
explants with 120 mg/1 colchicine for 28 days was the most efficient conditions for the induction, yielding 23.5%
tetraploid among all the regenerated shoots. These newly established protocols in organogenesis, doubling the
chromosome number of diploid E. purpurea plants have high applicable values for genetic improvements of the crop.
