Organismal and Evolutionary Biology Research Programme, Faculty of Biological and Environmental Sciences, Viikki Plant Science Centre, University of Helsinki, FIN-00014 Helsinki, Finland.
School of Science & Technology, The Life Science Center-Biology, Örebro University, SE-70182 Örebro, Sweden.
Plant Physiol. 2021 May 27;186(1):180-192. doi: 10.1093/plphys/kiab097.
Tropospheric ozone (O3) is a major air pollutant that decreases yield of important crops worldwide. Despite long-lasting research of its negative effects on plants, there are many gaps in our knowledge on how plants respond to O3. In this study, we used natural variation in the model plant Arabidopsis (Arabidopsis thaliana) to characterize molecular and physiological mechanisms underlying O3 sensitivity. A key parameter in models for O3 damage is stomatal uptake. Here we show that the extent of O3 damage in the sensitive Arabidopsis accession Shahdara (Sha) does not correspond with O3 uptake, pointing toward stomata-independent mechanisms for the development of O3 damage. We compared tolerant (Col-0) versus sensitive accessions (Sha, Cvi-0) in assays related to photosynthesis, cell death, antioxidants, and transcriptional regulation. Acute O3 exposure increased cell death, development of lesions in the leaves, and decreased photosynthesis in sensitive accessions. In both Sha and Cvi-0, O3-induced lesions were associated with decreased maximal chlorophyll fluorescence and low quantum yield of electron transfer from Photosystem II to plastoquinone. However, O3-induced repression of photosynthesis in these two O3-sensitive accessions developed in different ways. We demonstrate that O3 sensitivity in Arabidopsis is influenced by genetic diversity given that Sha and Cvi-0 developed accession-specific transcriptional responses to O3. Our findings advance the understanding of plant responses to O3 and set a framework for future studies to characterize molecular and physiological mechanisms allowing plants to respond to high O3 levels in the atmosphere as a result of high air pollution and climate change.
对流层臭氧（O3）是一种主要的空气污染物，它会降低全球重要作物的产量。尽管人们对其对植物的负面影响进行了长期研究，但我们对植物如何应对 O3 仍存在许多知识空白。在这项研究中，我们利用模式植物拟南芥（Arabidopsis thaliana）的自然变异来描述 O3 敏感性的分子和生理机制。模型中 O3 损伤的一个关键参数是气孔吸收。在这里，我们表明敏感拟南芥 accession Shahdara（Sha）中的 O3 损伤程度与 O3 吸收不成比例，这表明 O3 损伤的发展存在与气孔无关的机制。我们比较了耐受（Col-0）和敏感 accession（Sha、Cvi-0）在与光合作用、细胞死亡、抗氧化剂和转录调控相关的测定中。急性 O3 暴露会增加细胞死亡、叶片损伤的发展，并降低敏感 accession 的光合作用。在 Sha 和 Cvi-0 中，O3 诱导的损伤与最大叶绿素荧光的降低和从光系统 II 到质体醌的电子传递的量子产率降低有关。然而，这两个 O3 敏感 accession 中 O3 诱导的光合作用抑制以不同的方式发展。我们证明，拟南芥对 O3 的敏感性受遗传多样性的影响，因为 Sha 和 Cvi-0 对 O3 表现出特定 accession 的转录反应。我们的研究结果加深了对植物对 O3 反应的理解，并为未来的研究提供了框架，以表征允许植物因空气污染和气候变化导致大气中 O3 水平升高而做出反应的分子和生理机制。
