Regulation and Physiological Role of Isoprene Emission from Plants

9317900 Sharkey Isoprene从植物和动物中大量排放。 许多植物在光合作用中释放2%的碳作为异戊二烯，使其成为这些植物的主要代谢途径。 植物排放的异戊二烯严重影响大气化学。 异戊二烯排放的代谢控制以及对排放异戊二烯的植物和动物的益处尚不清楚。 许多类异戊二烯合成的调节受羟甲基戊二酰辅酶A还原酶（HMGR）的影响，并且据推测异戊二烯排放植物的大多数HMGR活性是异戊二烯合成所需的。 该项目涉及异戊二烯合成的调控，重点是HMGR和最近发现的异戊二烯合成酶。 异戊二烯合成所需的HMGR的位置将通过叶绿体分离和叶材料的非水分馏来确定。 这项研究将利用最近的发现，即一片叶子中的伤口诱导信号可以传播到第二片叶子，并在3分钟内将异戊二烯的排放率降低80%。 将测量该创伤信号到达之前和之后HMGR和异戊二烯合酶的活性以确定异戊二烯合成如何被调节。 这项研究还将利用发现，野葛（野葛）Ohwi。当在20 ℃下生长时，叶子不释放异戊二烯，但是通过在30 ℃下处理6小时可以诱导释放异戊二烯。 异戊二烯排放的生理作用将通过探索异戊二烯提供的光合机构的热保护的最新证据进行研究。 需要进行拟议的研究，以确定是否可能或需要改变植物的异戊二烯排放。 异戊二烯是合成橡胶的重要原料。 目前的市场是每年10亿美元。 由于异戊二烯的常见替代品-巴塔二烯的致癌性，一种廉价的异戊二烯生物来源可能对橡胶工业产生很大影响。 最后，游离异戊二烯的合成是植物和动物中的主要代谢途径，迄今为止在很大程度上被忽视。 了解异戊二烯排放的生理相关性可能会导致重要的和有用的见解，这还不能预测。 ***

9317900 Sharkey Isoprene is emitted from plants and animals in significant quantities. Many plants emit 2% of the carbon fixed in photosynthesis as isoprene making it a major metabolic pathway in these plants. Isoprene emitted from plants substantially affects atmospheric chemistry. The metabolic control of isoprene emission and the advantage to plants and animals which emit isoprene are unknown. The regulation of synthesis of many isoprenoids is affected by hydroxymethylglutaryl CoA reductase (HMGR) and it is speculated that most HMGR activity of isoprene emitting plants is required for isoprene synthesis. This project deals with the regulation of isoprene synthesis, focusing on HMGR and the recently discovered isoprene synthase. The location of the HMGR needed for isoprene synthesis will be determined by chloroplast isolation and by nonaqueous fractionation of leaf material. The research will exploit recent discovery that a wound-induced signal in one leaf can travel to a second leaf and reduce the rate of isoprene emission by as much as 80% within 3 minutes. The activity of HMGR and isoprene synthase before and after the arrival of this wound signal will be measured to determine how isoprene synthesis is regulated. The research will also exploit the discovery that kudzu (Pueraria lobata (Willd) Ohwi.) leaves do not emit isoprene when grown at 20 degree centigrade but can be induced to emit isoprene by a 6 hour treatment of 30 degree centigrade. The physiological role of isoprene emission will be investigated by exploring the recent evidence of thermal protection for the photosynthetic apparatus provided by isoprene. The proposed research is needed to determine whether it will be possible or desirable to modify isoprene emission from plants. Isoprene is an important raw material for synthetic rubber synthesis. The current market is one billion dollars per year. Because of carcinogenicity of the common substitute for isoprene, batadiene, an inexpensive biogenic source of isoprene could have a large impact on the rubber industry. Finally, the synthesis of free isoprene is a major metabolic pathway in plants and animals which has been largely overlooked until now. Understanding the physiological relevance of isoprene emission may lead to important and useful insights which cannot yet be predicted. ***