The increasing concentrations of ground‐level ozone (O3) resulting from industrialisation and anthropogenic activities present a substantial environmental threat to agricultural productivity, particularly affecting O3‐sensitive crops such as soybeans. The effects of acute O3 exposure on soybean yield attributes and seed quality and whether soybean showed different detoxification mechanisms in response to moderate and severe O3 stress are not extensively explored. In this study, soybean seedlings were exposed to moderate (80 nmol mol−1) and acute severe (200 nmol mol−1) O3 stress, and then growth parameters, yield attributes, reactive oxygen species (ROS) levels, enzymatic and non‐enzymatic antioxidant properties and associated gene expression in the leaves were assessed. The results revealed that moderate O3 exposure enhanced growth parameters but reduced the 100‐grain weight, while acute severe exposure sharply depressed growth parameters, yield attributes and the 100‐grain weight. Moderate O3 fumigation significantly increased hydrogen peroxide (H2O2) levels and catalase (CAT) activity from 4 to 32 h. Acute severe O3 stress induced the overproduction of superoxide anions (O2.−) and H2O2 during nearly the whole experiment period, but only enhanced superoxide dismutase (SOD) activity at 32 h, and showed no stimulatory effects on CAT activity. Additionally, the relative expression levels of the SOD and CAT gene family in soybean leaves exposed to elevated O3 were upregulated, peaking at 8 h. Moderate O3 treatment enhanced reduced glutathione (GSH) and ascorbate (AsA) levels and increased the activities of AsA–GSH cycle‐related enzymes. In contrast, acute severe O3 exposure inhibited GSH and AsA contents and markedly suppressed AsA–GSH cycle‐related enzymes, particularly from 8 to 32 h. Redundancy analysis indicated that CAT and AsA play crucial roles in scavenging O3‐induced ROS under moderate stress, while ascorbate peroxidase (APX) and GSH were more effective under acute severe stress conditions. These findings provide insights into the differential impacts of acute O3 stress on soybeans, emphasising the importance of considering both crop yield and grain quality in assessing O3 risks to crops.

中文翻译：

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急性中度和重度臭氧升高下大豆 （Glycine max） 植物化学物质和基因表达的比较分析：揭示抗氧化防御的作用


工业化和人为活动导致地面臭氧 （O3） 浓度的增加对农业生产力构成了重大环境威胁，尤其是影响大豆等对 O3 敏感的作物。急性 O3 暴露对大豆产量属性和种子质量的影响，以及大豆在响应中度和重度 O3 胁迫时是否表现出不同的解毒机制，并未得到广泛探讨。在这项研究中，大豆幼苗暴露于中度 （80 nmol mol-1） 和急性重度 （200 nmol mol-1） O3 胁迫下，然后评估生长参数、产量属性、活性氧 （ROS） 水平、酶和非酶抗氧化特性以及叶片中的相关基因表达。结果表明，适度的 O3 暴露增强了生长参数，但降低了 100 粒重，而急性重度暴露急剧降低了生长参数、产量属性和 100 粒重。中度 O3 熏蒸显着增加了 4 至 32 小时的过氧化氢 （H 2 O 2 ） 水平和过氧化氢酶 （CAT） 活性。急性重度 O3 应激在几乎整个实验期间诱导了超氧阴离子 （O2.−） 和 H2O2 的过量产生，但仅在 32 h 时增强了超氧化物歧化酶 （SOD） 活性，对 CAT 活性没有刺激作用。此外，暴露于高 O3 的大豆叶片中 SOD 和 CAT 基因家族的相对表达水平上调，在 8 h 达到峰值。中度 O3 处理增强了降低谷胱甘肽 （GSH） 和抗坏血酸 （AsA） 水平，并增加了 AsA-GSH 循环相关酶的活性。 相比之下，急性重度 O3 暴露抑制了 GSH 和 AsA 含量，并显着抑制了 AsA-GSH 循环相关酶，尤其是在 8 至 32 小时。冗余分析表明，CAT 和 AsA 在中度胁迫下清除 O3 诱导的 ROS 中起关键作用，而抗坏血酸过氧化物酶 （APX） 和 GSH 在急性严重胁迫条件下更有效。这些发现为急性 O3 胁迫对大豆的不同影响提供了见解，强调了在评估 O3 对作物的风险时考虑作物产量和谷物质量的重要性。