Optimal concentrations of plant growth regulators and cultivation conditions for plant regeneration from leaf explants of <i>Aster maackii</i>

The perennial plant Aster maackii has excellent antioxidant activity and high medicinal potential, making it a valuable plant resource.However, its natural habitat is expected to decrease in area owing to climate change; thus, ex situ conservation will be necessary.Therefore, we aimed to determine the optimal conditions for the propagation of Aster maackii using tissue culture techniques.Leaf explants were cultured on Murashige and Skoog (MS) medium treated with cytokinin hormones alone (6-benzylaminopurine [BAP], zeatin, thidiazuron [TDZ], 6-(,-dimethylallylamino)purine, and meta-topolin) or in combination with auxin hormones (1-naphthaleneacetic acid and indole-3butyric acid [IBA]) for 8 weeks, and the induction of shoots from explants was compared.We also attempted to determine the optimal light conditions by culturing explants under different light and dark conditions.In the cytokinin monotreatment group, highest shoot induction was observed under light conditions with 0.5 mg/L zeatin treatment.However, in the TDZ treatment group, leaf explants were hyperhydrated.In the cytokinin and auxin mixed treatment group, best results were achieved using 2.0 mg/L BAP and 0.5 mg/L IBA treatment under 4 weeks of dark followed by 4 weeks of light conditions.Additionally, shoot induction responses were observed only in the experimental group where BAP was added.Overall, cytokinin monotreatments were more effective for shoot induction than were combined treatments.Most healthy shoots were induced in the zeatin treatment group.Subsequently, shoots were subcultured on 1/2MS medium to induce rooting and shoot growth, and plantlets were obtained.