School of Life Science, Shanxi University, Taiyuan, 030006, Shanxi Province, China.
Ecotoxicology. 2022 May;31(4):637-648. doi: 10.1007/s10646-022-02530-w. Epub 2022 Mar 16.
Sulfur dioxide (SO) is a common air pollutant that has multiple effects on plants. In the present study, the improvement of drought tolerance in Arabidopsis plants by SO fumigation was investigated. The results showed that pre-exposure to 30 mg/m SO for 72 h could reduce water loss, stomatal conductance (Gs) and the transpiration rate (Tr) but increased the net photosynthetic rate (Pn), water use efficiency (iWUE) and photosynthetic pigment contents under drought conditions. The activities of superoxide dismutase (SOD) and peroxidase (POD) were significantly increased, while the contents of hydrogen peroxide (HO) and malondialdehyde (MDA) were decreased in SO-pretreated Arabidopsis plants under drought stress. Additionally, the activity of o-acetylserine(thio)lyase (OASTL) and the content of cysteine (Cys), the rate-limiting enzyme and the first organic product of sulfur assimilation, were significantly increased in drought-stressed plants after SO pretreatment, along with increases in other thiol-containing compounds, such as glutathione (GSH) and nonprotein thiol (NPT). Meanwhile, SO pre-exposure induced a higher level of proline accumulation, with increased activity of proline synthase P5CS and decreased activity of proline dehydrogenase ProDH. Consistent with the changes in enzyme activity, their corresponding gene expression patterns were different after SO treatment. Overall, the enhanced drought tolerance afforded by SO might be related to the improvement of plant photosynthesis, antioxidant defense, sulfur assimilation and osmotic adjustment. These findings provide new insights into the role of SO in plant adaptation to environmental stress.
二氧化硫（SO）是一种常见的空气污染物，对植物有多种影响。本研究探讨了 SO 熏蒸对拟南芥植物抗旱性的改善作用。结果表明，预暴露于 30mg/m 的 SO 中 72 小时可以减少水分流失、气孔导度（Gs）和蒸腾速率（Tr），但增加干旱条件下的净光合速率（Pn）、水分利用效率（iWUE）和光合色素含量。超氧化物歧化酶（SOD）和过氧化物酶（POD）的活性显著增加，而过氧化氢（HO）和丙二醛（MDA）的含量在 SO 预处理的拟南芥植物中降低。此外，在干旱胁迫下，O-乙酰丝氨酸（硫）裂解酶（OASTL）的活性和半胱氨酸（Cys）的含量，即硫同化的限速酶和第一个有机产物，在 SO 预处理的干旱胁迫植物中显著增加，同时其他含硫化合物，如谷胱甘肽（GSH）和非蛋白巯基（NPT）的含量也增加。同时，SO 预处理诱导脯氨酸积累水平升高，脯氨酸合成酶 P5CS 的活性增加，脯氨酸脱氢酶 ProDH 的活性降低。与酶活性的变化一致，SO 处理后它们相应的基因表达模式也不同。总的来说，SO 赋予植物更强的抗旱性可能与提高植物光合作用、抗氧化防御、硫同化和渗透调节能力有关。这些发现为 SO 在植物适应环境胁迫中的作用提供了新的见解。
