In vitro Culture of Endemic Astragalus gymnolobus Fischer and Comparison of its Antibacterial, Antioxidant, and Phenolic Profiles with Field Grown Plants

Astragalus gymnolobus Fischer (Leguminosae family) is an endemic plant to Turkey. Firstly, an in vitro regeneration system was achieved using leaf and petiole explants on Murashige and Skoog (MS) medium supplemented with different cytokinins [Thidiazuron (TDZ), Kinetin (KIN), Benzyladenine (BA)], auxins [Indole-3-Butyric Acid (IBA), Indole- 3-Acetic Acid (IAA), 2,4-Dichlorophenoxyacetic acid (2,4-D) and Naphthalene Acetic Acid (NAA)] and Gibberellic Acid (GA3) at diverse concentrations. Best shoot formation was obtained with leaf explants and only TDZ alone or TDZ and IAA combinations were effective for shoot forming. The best shoot inducing response (17.60 shoots per explant at 23.81% shoot frequency) was recorded at 0.5 mg L-1 TDZ alone. Among the TDZ standalone treatments, 0.05 and 0.1 mg L-1 TDZ were also effective in terms of shoot induction frequency (31.82 and 30.43%, respectively). Root formation was obtained after 3 months (3.5 roots per shoot with 77.8% root frequency) only in auxin free MS medium (control) when regenerated shoots were cut off 0.5-1 cm from the base to exclude the callus part. This study also aimed to determine and compare the antibacterial and antioxidant properties and phenolic composition of in vitro-regenerated and field-grown A. gymnolobus. The results revealed that field-grown leaves generally showed higher biological activities and had higher amounts of phenolic compounds. Furthermore, A. gymnolobus leaves were noteworthy sources of rutin. This initial in vitro culture protocol for endemic A. gymnolobus is valuable for genetic resources conservation and can be used in stress application studies to increase the level of phenolic substances in in vitro-grown plants.