The existing study held in the Plant Tissue Culture Laboratory, University of Tikrit, Iraq, sought to increase the production of some secondary metabolite compounds in tissue cultures of Chrysanthemum hortorum Hort. cv. ‘Dwarf White.’ Inducing callus by culturing the bases of young leaf explants on the MS medium received supplementation of different concentrations of Benzyl adenine (BA) (0, 1.5, and 2 mg L^-1) and Indole-3-acetic acid (IAA) (0.0, 0.5, and 1.5 mg L^-1). Tyrosine addition at different concentrations (0, 30, 60, and 80 mg L^-1) and sucrose at 30, 60, 80, and 100 g L^-1 concentrations ensued. In addition, fructose and glucose applications at 90.0, 60.0, 30.0, and 120.0 g L^-1 transpired for the callus growth. The combination of 2.0 mg L^-1 BA + 1.5 mg L^-1 IAA gave the highest average fresh and dry weights of callus, reaching 1.8 and 5.72 mg, respectively. The best treatment was 60 g L^-1, which recorded the maximum pyrethrin concentration, amounting to 2.134 μg/ml DW. The treatment of 90 g L^-1 fructose + 60 mg L^-1 tyrosine was more effective in increasing pyrethrin production in the callus, reaching 3.175 μg/ml DW. The treatment of 90 g L^-1 glucose + 60 mg L^-1 tyrosine was recorded with the utmost pyrethrin concentration, reaching 3.346 μg/ml DW. The treatment of 90 g L^-1 glucose + 80 mg L^-1 tyrosine provided 2.826 μg/ml DW of pyrethrin.

Keywords: Chrysanthemum hortorum, secondary metabolites, explants, carbon sources, pyrethrins, tyrosine, callus, in vitro

Key findings: Callus induction by culturing the base of young leaf explants on the MS medium had BA at 0, 1.5, and 2 mg L^-1 and IAA at 0.0, 0.5, and 1.5 mg L^-1 supplementations. The results showed that the combination of BA at a concentration of 2.0 and 1.5 mg L^-1 of IAA gave the highest average fresh and dry weights and the maximum percentage of callus. The above combination served to maintain induced callus. Secondary metabolite compounds gained estimation by the HPLC device.