Elevated Atmospheric CO2 and Cytosolic Control of Leaf Isoprene Biogenesis

从树叶中释放的异戊二烯在低层大气中引起光化学反应，从而导致许多重要的环境后果。例如，来自树木的异戊二烯有助于形成对流层臭氧污染，增加大气中甲烷的浓度，并产生可损害人类健康和植物生产力的含氮化合物。过去的研究表明，树木的异戊二烯排放受到大气二氧化碳浓度升高的抑制。这种抑制作用导致这样一种假设，即在未来，随着大气CO2浓度的增加，森林生态系统的异戊二烯排放量将减少。目前对在二氧化碳升高时控制异戊二烯排放的生理过程的了解不足以准确预测未来森林的异戊二烯排放。这个项目将提高我们对在二氧化碳浓度升高的大气中控制叶片异戊二烯排放的过程的理解，并将重点放在细胞水平的过程上。该项目验证了一种假设，即异戊二烯的排放在二氧化碳浓度升高时受到抑制，这是因为叶绿体和细胞的细胞质之间对碳底物的竞争。实验将集中于对大气中二氧化碳增加敏感的酶和过程的反应。该研究将利用先进的仪器和技术来验证大气中二氧化碳升高导致异戊二烯生物合成所需的叶绿体底物部分耗竭的假设。先进的仪器和技术包括质子转移反应质谱，以及酶纯化和表征的先进生化技术。这项研究将以专门为这项研究进行基因改造的杨树（杨树）进行。更广泛的影响这些研究将为一名博士后和两名研究生提供培训机会。该项目还将促进一门名为“森林生物技术与环境”的独特课程的发展。这项研究将促进科罗拉多大学和德国弗莱堡大学的Heinz Rennenberg教授之间的合作关系。蒙森教授和福尔教授参加了环境科学合作研究所（CIRES），该研究所旨在促进科罗拉多大学和美国国家海洋和大气管理局（NOAA）之间的跨学科研究。

Intellectual MeritThe emission of isoprene from the leaves of trees causes photochemical reactions in the lower atmosphere that lead to many important environmental consequences. For example, isoprene from trees contributes to the formation of tropospheric ozone pollution, an increase in the concentration of atmospheric methane, and the production of nitrogenous compounds that can harm human health and plant productivity. Past studies show that isoprene emissions from trees are inhibited by elevated atmospheric carbon dioxide (CO2) concentrations. This inihibition leads to the hypothesis that in the future, as the atmospheric CO2 concentration increases, the emission of isoprene from forest ecosystems will decrease. Current understanding of the physiological processes that control isoprene emission at elevated CO2 is inadequate for accurately predicting future isoprene emissions from forests. This project will improve our understanding of the processes that control isoprene emissions from leaves in an atmosphere of elevated CO2, and will focus on processes at the cellular level. The project tests the hypothesis that isoprene emissions are inhibited at elevated CO2 because of competition between the chloroplasts and the cytosol of the cell for carbon substrates. Experiments will focus on the response of the enzymes and processes known to be sensitive to increases in atmospheric CO2. The research will utilize advanced instrumentation and technologies to test the hypothesis that elevated atmospheric CO2 causes partial depletion of a chloroplast substrate needed for isoprene biosynthesis. Advanced instrumentation and technologies include proton transfer reaction mass spectrometry, and advanced biochemical techniques in enzyme purification and characterization. The research will be conducted with cottonwood (Populus) trees that are genetically transformed specifically for this study. Broader ImpactsThe studies will provide training opportunities for a postdoctoral student, and two graduate students. The project will also catalyze development of a unique course entitled, "Forest Biotechnology and the Environment." The research will foster the collaborative relationship between those at the University of Colorado, and those working with Professor Heinz Rennenberg at the Universitat Freiburg, Germany. Professors Monson and Fall participate in the Cooperative Institute for Research in Environmental Science (CIRES), that stimulates interdisciplinary research within and between the University of Colorado and the National Oceanic and Atmospheric Administration (NOAA).