Abstract:

In the context of global change, the increasing concentration of ozone (O₃) in the earth’s atmosphere will become an important stress factor for agricultural production in the future. In this study, soybean (Glycine Max), an important crop, was used as the rese arch material. Using the Open-Top Chambers method, three concentration gradients (control group, 80 nmol∙mol^-1, 200 nmol∙mol^-1) ozone fumigation experiments had been carried out for 9 days. Soybeans in each treatment branch stage were sampled in the recovery period within 1 h, 2 h, 4 h, 8 h, 24 h, 48 h, and 72 h after the fumigation. The changes of leaf membrane lipid peroxidation degree, antioxidant enzyme activity and related gene expression were analyzed, and the growth and seed setting characteristics were measured at the mature stage of soybean. The results showed that (1) the low-concentration (80 nmol∙mol^-1) ozone treatment significantly increased the number of pods and the number of seeds per plant at the milk ripening stage, but the seed weight per plant was less than that of the control. (2) Low-concentration ozone fumigation treatments increased the contents of ascorbic acid (ASA) and glutathione (GSH) and the activities of superoxide dismutase (SOD), ascorbic acid peroxidase (APX) and glutathione reductase (GR) in soybean leaves at the branching stage. During the 72-hour recovery period, the activity of antioxidant enzyme increased showing an oxidative stress response. (3) Fumigation with high concentration (200 nmol∙mol^-1) significantly increased the level of reactive oxygen species in soybean leaves at branching stage, decreased the activities of catalase (CAT), APX, GR, dehydroascorbic acid reductase (DHAR) and monodehydroascorbic acid reductase (MDHAR), decreased the expression of CAT1, APX and GR, and increased the content of MDA. In the recovery period, the activities of SOD, CAT, APX and GR increased, and the expression of related enzyme genes increased. This study showed that after the acute stress of low concentration ozone, in the recovery period, soybean can adapt to the oxidative stress caused by the increase of ozone concentration by increasing the activity of antioxidant enzymes and gene expression regulation, and increase the number of pods and grains per plant in reproduction to ensure the continuation of parents. However, acute high concentration stress will cause damages to the growth and adult reproduction of soybean, and the protective responses of the plant are generally ineffective in mitigating the damages.

Key words: soybean, Ozone, reproductive growth, reactive oxygen species level, antioxidant system, gene

摘要：

在全球变化背景下,近地层臭氧（O₃）浓度不断升高,将成为影响未来农业生产的重要因素。以大豆（Glycine max）为研究材料,采用OTCs方法,设置3个处理梯度（CK、80 nmol∙mol^-1、200 nmol∙mol^-1）臭氧熏蒸试验,试验进行9 d,在熏蒸结束后的72 h内（恢复期）分别采集各处理分枝期大豆,分析叶片膜脂过氧化程度、抗氧化酶活性及相关基因表达的变化情况,以及在大豆完熟期测定生长及结实性状。结果表明,（1）低浓度（80 nmol∙mol^-1）臭氧处理显著提高了完熟期大豆豆荚数和单株种子粒数,但种子单株粒质量小于对照。（2）低浓度臭氧熏蒸使分枝期大豆叶片抗坏血酸（AsA）、谷胱甘肽（GSH）含量升高,超氧化物歧化酶（SOD）、抗坏血酸过氧化物酶（APX）、谷胱甘肽还原酶（GR）活性上升,72 h内的恢复期间,抗氧化酶活性升高,表现出氧化应激反应。（3）高浓度（200 nmol∙mol^-1）熏蒸处理使分枝期大豆叶片活性氧水平显著升高,过氧化氢酶（CAT）、APX、GR、脱氢抗坏血酸还原酶（DHAR）、单脱氢抗坏血酸还原酶（MDHAR）活性下降,CAT1、APX、GR表达下调,MDA含量升高。在恢复期,SOD、CAT、APX、GR活性升高,相关酶基因表达上调。该研究表明低浓度（80 nmol∙mol^-1）臭氧急性胁迫后,在恢复期大豆能够通过升高抗氧化酶活性及基因表达调控适应臭氧浓度升高带来的氧化胁迫,并在生殖上提高豆荚及单株粒数,保证亲本投入。但急性高浓度（200 nmol∙mol^-1）胁迫将对大豆的生长和成株的生殖造成损害,且伤害难以恢复。

关键词: 大豆, 臭氧, 生殖生长, 活性氧水平, 抗氧化系统, 基因表达