In Vitro Callus Induction and Plant Regeneration of Endemic and Threatened Hypericum bilgehan-bilgilii with Various Plant Growth Regulators

Hypericum bilgehan bilgilii is a local endemic species distributed in Turkiye. Since the related species is endemic and there are grazing activities in its habitat, in vitro regeneration and in vitro cultures should be established. In addition, considering that the species may have medicinal properties similar to other Hypericum species, an effective in vitro regeneration method(s) should be found. For this reason, a more effective in vitro regeneration method has been established by using benzyl amino purine and 2,4 dichloro phenoxy acetic acid plant growth regulators (PGRs) for the first time in Hypericum bilgehan bilgilii. In this study, different concentrations and combinations of 2,4-D (0.3, 0.4, 0.5, and 1.0) and BAP (0.6, 0.8, 1.0, and 2.0) PGRs have been used for callus formation. It has been established that the best callus formation among the treatment groups occurs in MS supplemented with 0.8 mg L^–1 BAP + 0.4 mg L^–1 2,4-D. The best shoot growth has been found in MS medium containing 2.0 mg L^–1 BAP. The best treatment group in root formation was MS supplemented with 1.0 mg L^–1 IBA. It has been observed that the in vitro regenerated seedlings successfully adapted to the acclimatization stage. In the study, in vitro regeneration of Hypericum bilgehan-bilgilii using BAP and 2,4 D PGRs has been performed for the first time, and in vitro, cultures have been established for future plant biotechnology and in vitro conservation studies.