Unexpected Aftereffects of Low Dose γ-irradiation on Quality of Individual Dry Pea Seeds

Time-dependent aftereffect induced by γ-radiation in dry pea seeds at non-lethal 0.19–10 Gy doses is considered. By using phosphorescence at room temperature (RTP), seed lot was fractionated to strong and weak seeds producing normal and abnormal seedlings, respectively, and to dead seeds. After 0.19 Gy γ-radiation, strong seeds transformed to weak seeds during two months, whereas seeds after 7–10 Gy became weak during 2–4 days that was accompanied by doubling glucose content and decreasing seed hydration. This indicated non-enzymatic hydrolysis of carbohydrates apparently caused by γ-induced activation of water molecules. At 7–10 Gy, an unexpected back transition of weak seeds to “improved” seeds occurred, producing normal seedlings. This “improvement” is due to glucose decrease to strongseed level presumably via reaction between free glucose carbonyl and protein amino group. “Improvement” is transient; these seeds gradually die apparently due to end products of amino-carbonyl reaction (Amadori-Maillard products). Therefore, two effects of indirect non-target action of γ-radiation on dry seeds at low doses were suggested: non-enzymatic hydrolysis of carbohydrates and then amino-carbonyl reaction. They result at first in transition of strong to weak seeds and then of weak to “improved” seeds, response time being dependent on γ-radiation dose.