الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
 |  | from | 145 |  |  |
| | | from | 145 | | |
Abstract
This thesis presents a consolidated explanation of in vitro callus production and focuses on the effects of gamma irradiation on the in vitro growth of callus and suspension cultures of E. alata. An experiment was conducted to develop a protocol for the callus induction of Ephedra alata from nodal segments. The sterilization of nodal explants was done by using different chemicals, sodium hypochlorite (NaOCl) and mercury chloride (HgCl2), for different time intervals. The best surface sterilized by immersion in 35% Clorox solution for 30 min.
The effect of 2,4-D (as auxin) on callus induction was examined. It showed less callus initiation time and the highest callus induction frequency (CIF) percentage with a medium containing 3 mg/l 2,4-D compared to the other treatments. Also, different types and concentrations of growth regulators were tested in order to obtain callus multiplication and callus proliferation. The following hormonal ranges showed the highest fresh and dry weights among the other treatments: 2 mg/l 2,4-D and 0.5 mg/l Kin; 3 mg/l 2,4-D and 0.5 mg/l NAA.
The cell suspension and callus cultures were established on Murashige and Skoog’s medium (MS), supplemented with 0.5 mg/l (Kin) and 3 mg/l (2,4-D), and exposed to variable gamma radiation doses (0, 5, 10, 15, 20, 25, and 30 Gy). The findings demonstrated that in the cell suspension and callus cultures, 15 Gy achieved the highest fresh and dry weights when compared to the control. Similarly, the highest concentration of ephedrine and pseudoephedrine were found in suspension and callus cultures at 15 Gy as compared to control.
The antioxidant enzyme activities were affected due to high irradiation intensity. Significant changes in MDA were observed only under the highest irradiation dose compared to the non-irradiated (control). The total phenols and proline concentration increased slightly.