Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, Kreutzwaldi, Tartu, Estonia.
Estonian Academy of Sciences, Kohtu, Tallinn, Estonia.
J Exp Bot. 2019 Sep 24;70(18):5017-5030. doi: 10.1093/jxb/erz255.
Natural vegetation is predicted to suffer from extreme heat events as a result of global warming. In this study, we focused on the immediate response to heat stress. Photosynthesis and volatile emissions were measured in the leaves of tobacco (Nicotiana tabacum cv. Wisconsin 38) after exposure to heat shock treatments between 46 °C and 55 °C. Exposure to 46 °C decreased photosynthetic carbon assimilation rates (A) by >3-fold. Complete inhibition of A was observed at 49 °C, together with a simultaneous decrease in the maximum quantum efficiency of PSII, measured as the Fv/Fm ratio. A large increase in volatile emissions was observed at 52 °C. Heat stress resulted in only minor effects on the emission of monoterpenes, but volatiles associated with membrane damage such as propanal and (E)-2-hexenal+(Z)-3-hexenol were greatly increased. Heat induced changes in the levels of methanol and 2-ethylfuran that are indicative of modification of cell walls. In addition, the oxidation of metabolites in the volatile profiles was strongly enhanced, suggesting the acceleration of oxidative processes at high temperatures that are beyond the thermal tolerance limit.
自然植被预计将因全球变暖而遭受极端高温事件的影响。在这项研究中，我们专注于对热应激的即时响应。在暴露于 46°C 至 55°C 的热冲击处理后，测量了烟草（Nicotiana tabacum cv. Wisconsin 38）叶片中的光合作用和挥发性排放。暴露于 46°C 使光合碳同化率（A）降低了 >3 倍。在 49°C 时观察到 A 的完全抑制，同时 PSII 的最大量子效率（以 Fv/Fm 比衡量）下降。在 52°C 时观察到挥发性排放的大量增加。热应激仅对单萜的排放产生微小影响，但与膜损伤相关的挥发性物质，如丙醛和（E）-2-己烯醛+（Z）-3-己烯醇，大大增加。热诱导的甲醇和 2-乙基呋喃水平的变化表明细胞壁的修饰。此外，挥发性图谱中代谢物的氧化强烈增强，这表明在超过热耐受极限的高温下，氧化过程的加速。
