Physiological effects of glycinebetaine on gamma-irradiated fenugreek plants

Irradiation can adversely affect plant growth and development. The radio protective activity mechanism by glycinebetaine in plants is not known. Gamma rays at doses 0.0,25,50,100, and 150 Gray (Gy) from a cobalt source (⁶⁰Co) with strength of 500 Ci and the dose rate of 0.54 Gy·min^-11 were applied presowing to dry seeds of fenugreek (Trigonella foenum-graecum L.). Total dry weight and levels of chlorophyll, total protein, photosynthetic efficiency (¹⁴CO₂-fixation), accumulation of reducing, nonreducing, and total soluble sugars were reduced compared with unirradiated control. The general response to increased glycinebetaine dose and increasing irradiation dose was a reduction in measured variables as irradiation dose increased and with higher values for plants treated with 50 mM glycinebetaine. The exceptions were for total chlorophyll where values from plants treated with 150 Gy were equal regardless of glycinebetaine dose and for H₂O₂ amount, which increased as irradiation dose increased. For this last effect values were higher when the no glycinebetaine dose was applied to plants. Glycinebetaine protection was more pronounced against irradiation stress at lower doses of γ-rays. Posttreatment of irradiated seeds with glycinebetaine partially alleviated adverse effects of radiation. Pretreatment of seeds with glycinebetaine may play an effective role in the radio-repair mechanism.