抗旱性不同的两个大豆品种对外源H_2O_2的响应

Response of Two Soybean Cultivars with Different Drought Resistance to Exogenous H_2O_2

两个品种的大豆叶圆片经１０－４ｍｏｌ／Ｌ和１０－３ｍｏｌ／Ｌ的Ｈ２Ｏ２处理１２ｈ后，超氧物歧化酶（ＳＯＤ）、过氧化氢酶（ＣＡＴ）与谷胱甘肽还原酶（ＧＲ）活性明显增加，但１０－２ｍｏｌ／Ｌ的Ｈ２Ｏ２处理却使这些酶活性降低。抗旱性较强的大豆品种小粒豆１号较抗旱性较弱的鲁豆４号能维持较高的叶绿素含量和较高的ＳＯＤ、ＣＡＴ及ＧＲ活性，对Ｈ２Ｏ２的抗性较强。５０μｍｏｌ／Ｌ的亚胺环已酮（ＣＨＭ）能消除Ｈ２Ｏ２对ＳＯＤ、ＣＡＴ与ＧＲ活性的刺激作用，而同样浓度的放线菌素Ｄ（ＡＭＤ）则不能。

Leaf discs of a small-seed soybean cultivar Xiaolidou No. 1 (drought-resistant ) and a commonly cultivated cultivar Ludou No. 4 (drought-sensitive) were incubated in solutions containing different concentrations of H2O2 for 12 h in light and in darkness.The activities of enzymes involved in the scavenging of active oxygen species were analyzed. Measurement of chlorophyll contents in leaf discs showed a stronger resistance of Xiaolidou No. 1 than Ludou No. 4 to H2O2both in light and in darkness (Fig. 1 ).The activities of superoxide dismutase (SOD ), catalase (CAT ) and glutathione reductase (GR ) were increased by sublethal concentrations of H2O2 and were higher in Xiaolidou No. 1 than in Ludou No. 4 (Figs. 2￣4 ). This increase in the activities of SOD, CAT and GR was inhibited by the protein synthesis inhibitor cycloheximide (CHM), but not by actinomycin (AMD) (Fig. 5 ). At higher concentrations of H2O2 the activities of all these enzymes decreased, especially in Ludou No. 4. These results suggest that the induction of the activities of SOD, CAT and GR in response to sublethal concentration of H2O2 involves de novo protein synthesis, probably at the level of translation by long-life mRNA.