Impact of cytokinin BA and chemical stress Sorbitol on Callus growth and adventitious micro shoots regeneration of the plant Gerbera jamesonii Bolus" Malibu" cultivar grown In vitro

Abstract

The response of Gerbera jamesonii (Malibu) leaf bases to callus induction in media prepared with different concentrations of 0.0, 17.76, 26.64, 35.52, and 44.40 μmol L^-1 of BA, with a constant concentration of 4.30 μmol L^-1 of auxin (NAA), and the reaction of primary callus to varying concentrations of 24.0, 36.0, 48.0, and 60.0 g m L^-1 of the sugar alcohol sorbitol in inducing osmotic stress, encompassing aspects such as callus growth (measured by fresh weight, dry weight, and water content percentage) and adventitious shoot formation. The study results indicated that the media containing BA at a concentration of 44.40 μmol L^-1 and NAA at 4.30 μmol L-1 had a significant impact on the induction percentage compared to all other treatments. Callus and the largest diameter of the loose callus mass reached 100%, 3.23 cm respectively and over a period of 6.33 days. It was noted that with increasing the concentration of BA in the nutrient medium, the percentages gradually decreased with decreasing its concentration, while no response was shown in the percentage of callus induction in the BA-free medium, which reached 0.0%. The results showed that reducing the sorbitol concentration in the nutrient medium for the growth of primary callus to 24.0 g.L^-1 led to a significant increase in the average fresh and dry weight of callus and the percentage of its water content, which reached 8.517 g, 1.202 g, 85.857% respectively. The same concentration also achieved the highest average number of adventitious shoots and leaves, the longest shoots and leaf width, as micro-shoot per 100 mg reached 11.20, 9.60 leaf per shoot, cm 6.88, 0.94 cm, and all the characteristics decreased. (Callus growth and adventitious shoot generation) with a gradual increase in concentration in the medium.