初花期淹水胁迫对大豆叶片AsA-GSH循环的损伤及烯效唑的缓解效应

【目的】研究淹水胁迫对初花期（R1）大豆叶片抗坏血酸-谷胱甘肽（AsA-GSH）循环的影响及烯效唑（uniconazole,S3307）的调控效应,为提高大豆耐涝性及烯效唑的应用提供理论依据。【方法】2019年在黑龙江八一农垦大学国家杂粮工程技术研究中心盆栽场,以耐涝品种垦丰14和涝渍敏感品种垦丰16为试验材料,进行盆栽试验。待植株生长至R1期时叶片喷施S3307（浓度为50 mg·L^-1,喷施量为225 L·hm^-2）,喷施5 d后开始淹水胁迫处理,分别于淹水后0 d（R1+5）、5 d（R1+10）和恢复正常水分处理5 d（R1+15）后进行取样,以2个品种大豆正常水分管理为对照组(CK)、淹水胁迫处理（W）和淹水胁迫处理+S3307（W+S）为处理组,分别采用分光光度计法对各项生理指标进行测定,研究淹水胁迫对大豆叶片膜脂过氧化程度（MDA）、活性氧（ROS）和AsA-GSH循环系统中非酶抗氧化剂（AsA、DHA、GSH和GSSG）和关键酶（APX、GR、MDHAR和DHAR）的影响及S3307的缓解效应。【结果】R1期,淹水胁迫R1+5时,与CK相比,喷施S3307降低了垦丰14和垦丰16叶片内MDA、$\mathop{{O}}_{2}^{{\mathop{}_{\ ·}^{-}}}$产生速率和H₂O₂含量,同时提高了AsA-GSH循环中非酶抗氧化剂和关键酶含量,以维持ROS平衡,促进2种大豆品种的生长发育。淹水胁迫R1+10时,W处理增加了垦丰14和垦丰16 2个大豆品种叶片内MDA含量,分别较CK显著增加40.02%和37.53%,并加速了ROS（$\mathop{{O}}_{2}^{{\mathop{}_{\ ·}^{-}}}$和H₂O₂）的积累,淹水胁迫下2个品种$\mathop{{O}}_{2}^{{\mathop{}_{\ ·}^{-}}}$产生速率分别较CK显著增加60.29%和27.77%,H₂O₂含量分别较CK显著增加49.45%和43.40%,且涝渍敏感品种垦丰16的受害程度大于耐涝品种垦丰14,同时,在淹水胁迫下,2个品种叶片内的抗氧化物质和关键酶活性均有所提高,以适应淹水胁迫所产生的应激反应。叶面喷施S3307后,W+S处理可进一步提高2个大豆品种淹水胁迫下抗氧化物质（AsA、GSH）、氧化还原物质（DHA、GSSG）及总抗坏血酸（AsA+DHA）和总谷胱甘肽（GSH+GSSG）含量,并提高抗氧化酶（APX、GR、MDHAR、DHAR）活性,降低叶片MDA含量,抑制ROS积累,减少淹水胁迫对膜系统造成的伤害。恢复正常水分处理5 d（R1+15）后,2个品种W处理的上述指标均有所降低,但W+S处理能维持大豆叶片内较高的抗氧化酶活性和抗氧化物质含量,加速清除MDA和ROS的过度积累,促进淹水胁迫下大豆叶片内AsA-GSH循环运转,进而促进大豆品种叶片恢复至正常状态。【结论】淹水胁迫对大豆叶片膜脂过氧化程度、ROS积累及AsA-GSH循环中关键酶活性和非酶抗氧化剂具有不同程度的影响,喷施S3307可在一定程度上提高关键酶活性,提高抗氧化能力,减缓淹水胁迫所造成的危害。

Damage of AsA-GSH Cycle of Soybean Leaves Under Waterlogging Stress at Initial Flowing Stage and the Mitigation Effect of Uniconazole

【Objective】 The aim of this study was to investigate effects of waterlogging stress on the ascorbate-glutathione (AsA-GSH) cycle of soybean leaves and the regulating effect of uniconazole (S3307) during initial flowering stage (R1), so as to provide a theoretical basis for improving soybean waterlogging resistance and the application of uniconazole.【Method】 This study was conducted in the pot plant of the National Coarse Grain Engineering Technology Research Center of Bayi Agricultural University in Heilongjiang in 2019. The water-tolerant variety KenFeng 14 and the waterlogging-sensitive variety KenFeng 16 were used as test materials for pot planting experiments. The leaves were sprayed with S3307 (concentration 50 mg·L^-1, appropriate spray amount 225 L·hm^-2). After spraying S3307 for 5 days, the waterlogging stress treatment was started after 0 d (R1+5) and 5 d (R1+10) and normal water treatment for 5 days (R1+15) after sampling, respectively, and the various physiological indicators were measured by using spectrophotometer to study the degree of membrane lipid peroxidation (MDA) of soybean leaves under waterlogging stress. The effects of reactive oxygen species (ROS) and non-enzymatic antioxidants (AsA, DHA, GSH, and GSSG) and key enzymes (APX, GR, MDHAR, and DHAR) in the AsA-GSH circulatory system and the mitigating effects of S3307 were analyzed. 【Result】 In the R1 stage after R1+5 of waterlogging stress, compared with CK, the S3307 treatment reduced the MDA, $\mathop{{O}}_{2}^{{\mathop{}_{\ ·}^{-}}}$ production rate and H₂O₂ content, and also increased the content of non-enzyme antioxidants and key enzymes in the AsA-GSH cycle to maintain ROS balance, thus promoted the growth and development of two soybean varieties. At R1+10, W treatment significantly increased the MDA content in the leaves of the two soybean varieties, which were significantly increased by 40.02% and 37.53% higher than that of CK, respectively, and accelerated ROS ($\mathop{{O}}_{2}^{{\mathop{}_{\ ·}^{-}}}$ and H₂O₂); the $\mathop{{O}}_{2}^{{\mathop{}_{\ ·}^{-}}}$ production rate of the two varieties under waterlogging stress was significantly increased by 60.29% and 27.77%, compared with CK, respectively; The H₂O₂ content was significantly increased by 49.45% and 43.40% compared with CK, respectively; The waterlogging sensitive variety KenFeng 16 suffered more damage than the waterlogging resistant variety KenFeng 14, and at the same time, under the waterlogging stress, the antioxidant substances and key enzyme activities in the leaves of both soybean varieties were increased to adapt to the waterlogging stress response from stress. After S3307 treatment, W+S treatment could further increase antioxidant substances (AsA, GSH), redox substances (DHA, GSSG), total ascorbic acid (AsA + DHA) and total glutathione (GSH +GSSG) content under waterlogging stress.content, and increase the activity of antioxidant enzymes (APX, GR, MDHAR, DHAR), reduce the MDA content of the leaves, inhibit the accumulation of ROS, and reduce the damage caused by waterlogging stress to the membrane system. After returning to normal water treatment for 5d (R1 + 15), the above indexes of two soybean varieties W treatment were reduced, but W+S treatment could maintain the two soybean leaves. The higher antioxidant enzyme activity and antioxidant substance content accelerated the removal of excessive accumulation of MDA and ROS, promoted the AsA-GSH cycle operation in soybean leaves under waterlogging stress, and then promoted the return of the two soybean varieties to normal state.【Conclusion】 Waterlogging stress had different degrees of influence on membrane lipid peroxidation, ROS accumulation, and key enzyme activities and non-enzyme antioxidants in the AsA-GSH cycle of soybean leaves. Spraying S3307 could improve key enzyme activity at some extent to promote oxidation ability, so as to reduce the harm caused by waterlogging stress.