Ooi Lia, Matsuura Takakazu, Mori Izumi C
Institute of Plant Science and Resources, Okayama University, 2-20-1 Chuo, Kurashiki, Okayama 710-0046, Japan.
Plant & Microbial Research Unit, Research, Technology & Value Creation Division, Nagase Viita Co., Ltd., 675-1 Fujisaki, Naka-ku, Okayama 702-8006, Japan.
Plant Cell Physiol. 2025 Aug 12;66(7):1076-1085. doi: 10.1093/pcp/pcaf042.
Guard cells surrounding the stomata play a crucial role in regulating the entrance of hazardous gases such as SO2 into leaves. Stomatal closure could be a plant response to mitigate SO2 damage, although the mechanism for SO2-induced closure remains controversial. Proposed mediators for SO2-induced stomatal closure include phytohormones, reactive oxygen species, gasotransmitters, and cytosolic acidification. In this study, we investigated the mechanism of stomatal closure in Arabidopsis in response to SO2. Despite an increment in auxin and jasmonates after SO2 exposure, the addition of auxin did not cause stomatal closure and jasmonate-insensitive mutants exhibited SO2-induced stomatal closure suggesting auxin and jasmonates are not mediators leading to the closure. In addition, supplementation of scavenging reagents for reactive oxygen species and gasotransmitters did not inhibit SO2-induced closure. Instead, we found that cytosolic acidification is a credible mechanism for SO2-induced stomatal closure in Arabidopsis. CLCa mutants coding H+/nitrate antiporter, involved in cytosolic pH homeostasis, showed less sensitive stomatal phenotype against SO2. These results suggest that cytosolic pH homeostasis plays a tenable role in SO2 response in guard cells.
围绕气孔的保卫细胞在调节诸如二氧化硫等有害气体进入叶片方面起着关键作用。气孔关闭可能是植物减轻二氧化硫损害的一种反应，尽管二氧化硫诱导关闭的机制仍存在争议。提出的介导二氧化硫诱导气孔关闭的物质包括植物激素、活性氧、气体信号分子和细胞质酸化。在本研究中，我们调查了拟南芥中气孔对二氧化硫响应的关闭机制。尽管二氧化硫暴露后生长素和茉莉酸增加，但添加生长素并未导致气孔关闭，且茉莉酸不敏感突变体表现出二氧化硫诱导的气孔关闭，这表明生长素和茉莉酸不是导致关闭的介导物质。此外，添加活性氧和气体信号分子的清除剂并未抑制二氧化硫诱导的关闭。相反，我们发现细胞质酸化是拟南芥中二氧化硫诱导气孔关闭的可靠机制。编码参与细胞质pH稳态的H⁺/硝酸盐反向转运蛋白的CLCa突变体对二氧化硫表现出不太敏感的气孔表型。这些结果表明，细胞质pH稳态在保卫细胞对二氧化硫的响应中起着重要作用。
