The effect of plant growth regulators on the antioxidant enzyme activity and secondary metabolite production in the cell suspension cultures of Melia azedarach L.

In the present study, we investigated the effect of plant growth regulators and explant type on callus induction, cell suspension culture growth, antioxidant enzyme activity, and accumulation of rutin, quercetin, and kaempferol in M. azedarach L. cell cultures. Our studies showed that the inflorescence and petiole explants had a high percentage of callus induction compared to the leaf explants, whereas the highest callus growth was obtained from the leaf explants cultured on the MS medium containing 5 mg l⁻¹ NAA and 5 mg l⁻¹ BAP and 5 mg l⁻¹ NAA and 3 mg l⁻¹ kinetin Kin. Furthermore, the highest cell growth was obtained from the leaf and inflorescence calli transferred to liquid MS medium supplemented with 1 mg l⁻¹ 2,4-dichlorophenoxyacetic acid (2,4-D)+1 mg l⁻¹ Kin/BAP. The highest activity of antioxidant enzymes and the lowest protein content was related to the leaf cell suspension cultures in liquid MS medium containing 3 mg l⁻¹ NAA and 3 mg l⁻¹ BAP. The inflorescence cell suspension cultures in the MS medium containing 3 mg l⁻¹ NAA+1 mg l⁻¹ BAP exhibited the highest rutin accumulation (47.536 mg g⁻¹ FW). However, the highest amount of quercetin (8.570 mg g⁻¹ FW) and kaempferol (5.420 mg g⁻¹ FW) accumulation were obtained from the petiole cell suspension cultures in the MS medium with 1 mg l⁻¹ 2,4-D +1 mg l⁻¹ Kin.