気中汚染物質に対する植物防御の統合的システムに関する分子生理学的研究

二氧化硫是一种有毒气体。植物有一种机制，通过关闭气孔来防止硫氧化物气体侵入内部组织。气孔是植物叶片表面由一对保卫细胞形成的微小开口。一些植物生长调节剂也被假设参与保护细胞中的二氧化硫信号，但其原理尚不清楚。本研究采用液相色谱-质谱联用技术对植物生长调节剂、赤霉素、生长素、细胞分裂素、脱落酸、茉莉酸和水杨酸进行了定量分析。我们鉴定了茉莉酸盐的含量。因此，我们研究了一个茉莉素不敏感突变体的气孔运动。与我们的预期相反，茉莉酸不敏感突变体的气孔在二氧化硫响应中没有表现出损伤，这表明茉莉酸不参与二氧化硫诱导的气孔关闭。除了上述实验外，我们还对细胞质酸化是否参与保护细胞的二氧化硫信号传导提出了疑问。我们对CLCa基因突变稳定保护细胞pH的突变体进行了分析。CLCa突变体在诱导气孔关闭和保护细胞死亡方面对二氧化硫的抗性增强。这支持了细胞质酸化参与保护细胞中二氧化硫信号导致气孔关闭的观点。同时，这也为培育抗二氧化硫作物提供了一种潜在的方法。

Sulfur dioxide is a toxic gas. Plants has a mechanism to prevent the invasion of sulfur oxide gas into the internal tissue by closing stomata. Stomata is a microscopic opening formed by a pair of guard cells on leaf surface in plants.Some plant growth regulators are also postulated to participate in sulfur dioxide signaling in guard cells by earlier studies, while its rationale was obscure. In this study, we employed quantitative analysis of plant growth regulators, gibberellins, auxin, cytokinines, abscisic acid, jasmonates, and salicylic acid, by liquid chromatography-mass spectrometry. We identified that contents of jasmonates. Therefore, we examined the movement of stomata in a jasmonate-insensitive mutant. Contrary to our expectation, stomata of thejasmonate-insensitive mutant did not show an impairment in sulfur dioxide response, indicating that jasmonate does not participate to sulfur dioxide-induced stomatal closure.Beside above experiment, we have questioned whether cytosolic acidification participates in sulfur dioxide signaling in guard cells or not. We employed an analysis of the mutants, which have stabilized pH of guard cells by mutation in CLCa gene. The mutants of CLCa showed an intensified resistance to sulfur dioxide in terms of stomatal closure induction as well as cell death of guard cells. This supports the idea that cytosolic acidification participates in sulfur dioxide signaling in guard cell leading to stomatal closure. At the same time this provides a potential approach to generate sulfur dioxide-resistant crops.