Non-Methane Hydrocarbon Emmissions from Plants

尽管每年有大量的挥发性有机化合物（VOCs）从植被释放到大气中，但尚不清楚为什么植物要消耗大量的能量来合成挥发性和活性VOCs。这些排放影响着全球对流层的化学性质，这一事实强调了了解调节排放的基本过程的重要性。由于人类的影响，植物的进化条件与当今整个工业世界的环境大不相同。在我们更好地了解导致这些化合物排放的基本机制之前，我们将无法评估这些变化的条件目前对植被的影响，或者这些植物及其排放将如何应对进一步的全球变化。本研究将解决三个基本问题：1)主要挥发性有机化合物的生物合成和向大气排放的潜在机制是什么？2)管制挥发性有机化合物排放的主要物理和生物“驱动因素”是什么？3) VOCs是如何从植物表面排出的？要研究的生物源性挥发性有机化合物包括构成大部分自然排放的有机物：非甲烷碳氢化合物、异戊二烯和单萜烯；氧合碳氢化合物，甲醇，乙醇，乙醛，丙酮，2甲基-3-丁烯-2-醇（甲基丁烯醇），以及己烯醛家族（己烯醛，醋酸己烯酯）。例如，详细的实验将检验；2)甲醇、丙酮甲基丁烯醇和异戊二烯的生物合成机理；b)异戊二烯是一种“泄漏”的代谢中间体的可能性，而叶片可以解释为什么异戊二烯排放植物的排放范围从高到低；c)光、温度、湿度、二氧化碳浓度、气孔导度和叶片发育作为VOC排放的主要“驱动因素”的作用。此外，d)将进行实验，以确定角质层表面和气孔在叶片挥发性有机化合物出口中的作用，包括针叶中单萜烯的排放。这些研究应该为植物如何以及为什么排放挥发性有机化合物提供新的见解，减少排放“驱动因素”的不确定性，并允许预测未来挥发性有机化合物的排放以应对全球变化。

ATM-9312153 Fall Although tremendous quantities of volatile organic compounds (VOCs) are released from vegetation into the atmosphere annually, it is not clear why plants expend a considerable amount of energy synthesizing volatile and reactive VOCs. The fact that these emissions shape global tropspheric chemistry underscores the importance of developing an understanding of the underlying processes that regulate emissions. Plants evolved under conditions which, due to man's influence, are much different that present day conditions throughout the industrial world. Until we better understand the basic mechanisms that are responsible for the emission of these compounds, we will not be able to assess the effects that these changing conditions have on vegetation currently, or how these plants and their emissions will respond to further global change. This research will address three fundamental questions: 1) What are the underlying mechanisms for the biosynthesis and emission of major classes of VOCs to the atmosphere? 2) What are the major physical and biological "drivers" that regulate VOC emissions? 3) How do VOCs exit plant surfaces? The biogenic VOCs to be studied include those organics that make up the majority of natural emissions: the non-methane hydrocarbons, isoprene and monoterpenes; and the oxygenated hydrocarbons, methanol, ethanol, acetaldehyde, acetone, 2 methyl-3-buten-2-ol (methyl butenol), and the hexenal family (hexenal, hexenyl acetate). For example, detailed experiment will examine; 2) the mechanisms of methanol, acetone methyl butenol, and isoprene biosynthesis; b) the possibility that isoprene is a "leaky" metabolic intermediate and that leafiness may explain why isoprene-emitting plants range form high to low emitters: and c) the role of light, temperature, humidity, carbon dioxide concentration, stomatal conductance and leaf development as major "drivers" of VOC emissions. In addition, d) experiments will be conducted to establish the role of cuticle surfaces and stomatal pores in the exit of VOCs from leaves, including the emission of monoterpenes from conifer needles. These studies should provide new insights into how and why plants emit VOCs, reduce uncertainties about the "drivers" of emissions, and allow prediction of future VOC emissions in response to global change.