为了了解卫星搭载对紫花苜蓿种子化学特性的影响, 揭示空间诱变机理, 文章利用傅里叶变换拉曼光谱法对卫星搭载当代的紫花苜蓿种子进行了研究。 结果表明, 与地面对照相比, 飞行组在358和553 cm-1处的峰强增加, 814, 1 122, 1 531, 1 743 cm-1处的峰强降低, 通过谱带归属发现, 增强的358和553 cm-1分别与DNA和Ca2+有关, 降低的4个峰与糖类、 脂类有关。 这说明经过卫星搭载后, 苜蓿种子的DNA和Ca2+的量出现增加趋势, 糖类与脂类的量出现降低趋势。 其可能原因是(1)种子主动修复诱变产生的DNA损伤时, 消耗部分贮存能量所致; (2)空间飞行过程中的超重导致种子细胞内的Ca2+ 浓度升高; (3)飞行因子导致种子提前萌发, DNA大量合成与复制, 种子储藏的能量提前降解消耗。 这一结果将对苜蓿空间诱变机理研究有重要参考价值。

To realize the effect of space flight factors on chemical component of alfalfa seeds and its possible mechanism, seeds were loaded onto satellite “Jianbing No.1” in 2006 for 14 days’ space flight and then analyzed by Raman spectroscopy. Results showed that the intensity of two peaks (358 and 553 cm-1) of space flight seeds had been increased and the intensity of four peaks (814, 1 122, 1 531 and 1 743 cm-1) of space flight seeds had been decreased compared with its ground control. Based on the classification of Raman spectra, the increased peaks of 358 and 553 cm-1 are related to DNA and Ca2+ respectively, which mean that the content of DNA and Ca2+ of alfalfa seeds had increased after space flight. The decreased peaks of 814, 1 122 and 1 743 cm-1 are related to saccharide and fatty acid respectively, which mean that the content of reserve energy of alfalfa seeds had decreased after space flight. These findings can be explained as follows: (1) The increase in the content of DNA may be explained by the DNA damage induced by space flight factors and DNA syntheses and duplication before the cell division. (2) The increase in the content of Ca2+ may be stimulated by the complexity of gravity during the space flight, especially the hypergravity. Recent researches in Abrabidopsis thaliana have provided additional proof. (3) The decrease of the energy materials such as saccharide and fatty acid may be explained by the consumption both during the repair process of DNA damage induced by cosmic radiation and during the germination of seeds because the dormancy of alfalfa seeds had been broken up by space flight factors (cosmic radiation, microgravity, vibration or others) which subsequently resulted in that nutritious materials of alfalfa seeds were used earlier than its ground control.