不同基因型水稻苗期抗氧化系统对低温胁迫的响应

以2个籼型水稻(Oryza sativa L. subsp. indica Kato)和2个粳型水稻(O. sativa L. subsp. japonica Kato)品种为材料,比较其幼苗经低温胁迫和恢复生长后的活性氧(ROS)代谢、抗氧化酶活性、抗氧化剂含量和渗透调节物质的变化。结果显示,经低温胁迫后,4个水稻品种的H_2O_2含量均显著升高;抗氧化酶系统中的5种酶活性均有不同程度升高,且超氧化物歧化酶(SOD)的活性增加显著,而谷胱甘肽还原酶(GR)的活性增加不显著。抗氧化剂还原型谷胱甘肽(GSH)和还原型抗坏血酸(AsA)在‘明恢86’中显著增加。渗透调节物质脯氨酸的含量在‘黔恢1385’和‘日本晴’中变化不显著;可溶性糖含量在‘明恢86’中变化不显著。经过7 d恢复生长后,4个水稻品种的上述各生理指标均不同程度恢复到处理前的水平。研究结果表明,抗氧化酶活性的升高有效降低了ROS的水平,缓解了低温冷害对细胞膜的伤害。低温胁迫时细胞内维持了较高的可溶性糖含量,提高了胞内水势,减少因细胞失水而对植物造成的伤害。

Responses of antioxidant system in different genotypes of Oryza sativa seedlings to cold stress

We explored the physiological mechanism of Oryza sativa L. seedlings to resist low temperature stress and different physiological mechanisms of cold tolerance between indica O. sativa and japonica O. sativa. Two indica varieties (O. sativa L. subsp. indica Kato) and two japonica varieties (O. sativa L. subsp. japonica Kato) were used as materials. We compared the changes in reactive oxygen species (ROS) metabolism, antioxidant enzyme activities, antioxidant contents, and osmotic adjustment substances in O. sativa seedlings after low temperature stress and normal temperature recovery. Results showed that the content of H₂O₂ in the four varieties increased significantly after low temperature stress. The activities of the five enzymes in the antioxidant enzyme system increased to varying degrees; the activity of superoxide dismutase (SOD) increased significantly, whereas that of glutathione reductase (GR) did not. Glutathione (GSH) and ascorbic acid (AsA) were significantly increased in ‘Minghui 86’. The content of the osmotic adjustment substance proline was not significantly changed in ‘Qianhui 1385’ or ‘Nipponbare’, and the soluble sugar content was not significantly changed in ‘Minghui 86’. After 7 d of recovery, the above physiological indices of the four varieties were restored to pre-treatment levels to varying degrees. Results showed that antioxidant enzyme activity effectively reduced the level of ROS and alleviated the damage caused by cold stress to the cell membrane. During low temperature stress, the cells maintained high osmotic adjustment substances, increased intracellular water potential, and reduced damage caused by plant water loss. Therefore, the timely response of various cold-tolerant physiological substances in the cells and the synergistic and efficient operation of the antioxidant system are important physiological indicators for measuring the cold tolerance of O. sativa.