In vitro chromosome doubling of African daisy, Gerbera jamesonii Bolus cv. Mini Red

Abstract

A protocol for in vitro polyploidy induction was developed in Mini Red cultivar of African daisy (Gerbera jamesonii). Various concentrations of colchicine (0, 0.05, 0.1, 0.2, 0.5 and 1%) were applied with different exposure durations (2, 4 and 8 h) on 2 weeks old explants originated from in vitro induced Gerbera shoots. Murashige and Skoog (MS) medium supplemented with 8.8 μM 6-benzyladenine (BAP) plus 11.4 μM indole-3-acetic acid (IAA) were used for proliferation of the explants. Root induction occurred when proliferated colchicine-treated shoots transferred to the half strength MS medium supplemented with 3.99 μM IAA. The results of analysis based on the comparison of means revealed that increasing concentrations of colchicine led to significant reduction in survival rate of Gerbera in longer exposure durations; however we achieved the highest survival rate with polyploidy induction by using 0.1% (w/v) colchicine for 8 h. We obtained the highest percentage of tetraploid plants (53.3%) by applying 0.2% colchicine for 2 h. Direct chromosome counting method verified the duplicated chromosome number in colchicine-induced tetraploid plants (2n = 4x = 48) in comparison with intact diploid plants of Gerbera (2n = 2x = 24). Colchicine-induced tetraploid plants of Gerbera represented reduced stomata density with wider size than their diploid relatives. In vitro tetraploidy induction led to larger flower size, longer stalks, broader leaf length and width and lower shoots in Mini Red cultivar of Gerbera. The optimized polyploidy induction protocol has high commercial value and can be also applicable for in vitro micropropagation of Gerbera.