Plant surface reactions: an opportunistic ozone defence mechanism impacting atmospheric chemistry
Plant surface reactions: an opportunistic ozone defence mechanism impacting atmospheric chemistry
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DOI：
10.5194/acp-16-277-2016
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发表时间：
2016-01-01
影响因子：
6.3
通讯作者：
Hansel, A.
中科院分区：
文献类型：
--
作者：
Jud, W.;Fischer, L.;Hansel, A.
对流层臭氧浓度升高被认为是对植物的有毒威胁，造成全球农作物损失，每年造成数十亿美元的相关经济损失。植物伤害与通过气孔吸收臭氧和内部叶片组织的氧化损伤有关。但一个引人注目的问题仍然存在：表面反应是否可以限制气孔对臭氧的吸收，从而减少其对植物的有害影响？在这项实验室研究中，我们可以表明，不同烟草品种的腺毛分泌的半挥发性有机化合物是一个有效的臭氧汇在植物表面。在我们的实验中，不同的二萜类化合物是负责一个强烈的品种依赖的臭氧吸收植物在黑暗条件下，气孔几乎关闭时。臭氧的表面反应伴随着含氧挥发性有机化合物的迅速释放，这可能与相应的前体化合物有关：顺式冷杉醇（C20 H34 O）-一种具有两个环外双键的二萜类化合物-的臭氧分解引起甲醛（HCHO）和甲基乙烯基酮（C4 H6 O）的排放。具有三个内环双键的环结构的三烯二醇（C20 H34 O2）需要至少两个臭氧分解步骤才能形成挥发性羰基化合物如4-氧代戊醛（C5 H8 O2），这在气相中也能观察到。在臭氧反应性叶表面的情况下，在气孔附近的臭氧梯度的变化，通过开放的气孔的臭氧通量强烈reduced.Our研究结果表明，在植物表面的不饱和半挥发性化合物应被视为含氧挥发性有机化合物的来源，影响气相化学，以及有效的臭氧汇提高植物的臭氧耐受性。
Elevated tropospheric ozone concentrations are considered a toxic threat to plants, responsible for global crop losses with associated economic costs of several billion dollars per year. Plant injuries have been linked to the uptake of ozone through stomatal pores and oxidative damage of the internal leaf tissue. But a striking question remains: can surface reactions limit the stomatal uptake of ozone and therefore reduce its detrimental effects to plants?In this laboratory study we could show that semi-volatile organic compounds exuded by the glandular trichomes of different Nicotiana tabacum varieties are an efficient ozone sink at the plant surface. In our experiments, different diterpenoid compounds were responsible for a strongly variety-dependent ozone uptake of plants under dark conditions, when stomatal pores are almost closed. Surface reactions of ozone were accompanied by a prompt release of oxygenated volatile organic compounds, which could be linked to the corresponding precursor compounds: ozonolysis of cis-abienol (C20H34O) - a diterpenoid with two exocyclic double bonds - caused emissions of formaldehyde (HCHO) and methyl vinyl ketone (C4H6O). The ring-structured cembratrien-diols (C20H34O2) with three endocyclic double bonds need at least two ozonolysis steps to form volatile carbonyls such as 4-oxopentanal (C5H8O2), which we could observe in the gas phase, too.Fluid dynamic calculations were used to model ozone distribution in the diffusion-limited leaf boundary layer under daylight conditions. In the case of an ozone-reactive leaf surface, ozone gradients in the vicinity of stomatal pores are changed in such a way that the ozone flux through the open stomata is strongly reduced.Our results show that unsaturated semi-volatile compounds at the plant surface should be considered as a source of oxygenated volatile organic compounds, impacting gas phase chemistry, as well as efficient ozone sink improving the ozone tolerance of plants.