This study addressed the interactions between salt stress and the antioxidant responses of a halophytic grass, Desmostachya bipinnata. Plants were grown in a semi-hydroponic system and treated with different NaCl concentrations (0 mM, 100 mM, 400 mM) for a month. ROS degradation enzyme activities were stimulated by addition of NaCl. Synthesis of antioxidant compounds, such as phenols, was enhanced in the presence of NaCl leading to accumulation of these compounds under moderate salinity. However, when the ROS production rate exceeded the capacity of enzyme-controlled degradation, antioxidant compounds were consumed and oxidative damage was indicated by significant levels of hydrogen peroxide at high salinity. The cellular concentration of salicylic acid increased upon salt stress, but since no direct interaction with ROS was detected, a messenger function may be postulated. High salinity treatment caused a significant decrease of plant growth parameters, whereas treatment with moderate salinity resulted in optimal growth. The activity and abundance of superoxide dismutase (SOD) increased with salinity, but the abundance of SOD isoforms was differentially affected, depending on the NaCl concentration applied. Detoxification of hydrogen peroxide (H2O2) was executed by catalase and guaiacol peroxidase at moderate salinity, whereas the enzymes detoxifying H2O2 through the ascorbate/glutathione cycle dominated at high salinity. The redox status of glutathione was impaired at moderate salinity, whereas the levels of both ascorbate and glutathione significantly decreased only at high salinity. Apparently, the maximal activation of enzyme-controlled ROS degradation was insufficient in comparison to the ROS production at high salinity. As a result, ROS-induced damage could not be prevented, if the applied stress exceeded a critical value in D. bipinnata plants.

中文翻译：

---

盐诱导Desmostachya bipinnata的抗氧化防御系统中的调节作用。

这项研究解决了盐胁迫与盐生草Desmostachya bipinnata的抗氧化反应之间的相互作用。使植物在半水培系统中生长，并用不同的NaCl浓度（0 mM，100 mM，400 mM）处理一个月。通过加入NaCl刺激ROS降解酶活性。在NaCl的存在下，抗氧化剂化合物（如酚类）的合成得到增强，导致这些化合物在中等盐度下积累。但是，当ROS生成速率超过酶控制的降解能力时，抗氧化剂化合物被消耗，并且在高盐度下过氧化氢的显着水平表明了氧化损伤。水杨酸的细胞浓度在盐胁迫下会增加，但是由于未检测到与ROS的直接相互作用，信使功能可能是假定的。高盐度处理导致植物生长参数显着下降，而中度盐度处理导致最佳生长。盐度增加了超氧化物歧化酶（SOD）的活性和丰度，但是SOD异构体的丰度却受到不同的影响，具体取决于所用的NaCl浓度。过氧化氢（H2O2）的解毒作用是在中等盐度下通过过氧化氢酶和愈创木酚过氧化物酶进行的，而在高盐度下，通过抗坏血酸/谷胱甘肽循环对H2O2进行解毒的酶则占主导。在中等盐度下，谷胱甘肽的氧化还原状态受到损害，而仅在高盐度下，抗坏血酸盐和谷胱甘肽的水平才显着降低。显然，与高盐度条件下产生的ROS相比，酶控制的ROS降解的最大活化作用还不够。结果，如果施加的压力超过双子叶植物中的临界值，则不能防止ROS诱导的损害。