In this research the effect of thidiazuron (TDZ) on shoot regeneration of endemic Astragalus schizopterus was investigated in Turkish flora. Explants (leaf and petiole) were cultured on the basic media Murashige and Skoog medium (MS) containing various plant growth regulators (PGRs) [0.0, 0.4, 0.5, 0.6 mg l-1 thidiazuron (TDZ); 0.4, 0.5, 0.6 mg l-1 TDZ x 0.1, 0.2 mg l-1 α-naphthaleneacetic acid (NAA)] to induce shoot bud induction and somatic embryogenesis. The combinations and concentrations of PGRs showed significant variations for the frequency of callus formation, appearance of callus and the potential of callus differentiation. Callus formation occurred in cultures, but it was not obtained in adventitious shoot regeneration. Therefore, rapid multiplication was made by using lateral meristem which were obtained from 4 weeks sterile seedling. Lateral meristems were cultured on basic media MS containing various PGRs 0.5, 1.0 mg l-1 zeatin (ZEA), benzyladenine (BA) and 0.22, 0.5 and 1 mg l-1 TDZ. The highest number of shoots (23.6/explants) was obtained on MS containing 1 mg l-1 TDZ. It was observed that shoots didn’t have healthy development in all media containing TDZ. So it was suggested that a media containing 1 mg l-1 BA in order to get healthier shoots in rapid multiplication.
The regenerated shoots were transferred to rooting medium [MS with 0.5-1 mg l-1 NAA and 0.5-1 mg l-1 indole-3-butyric acid (IBA)] where they were successfully rooted (100%) and showed rapid elongation. Rooted shoots were transferred to the ex vitro and produced normal plants.