Molecular Regulation of the Capacity for Isoprene Synthesis in Plants

植物异戊二烯合成能力的分子调控

• 批准号: 0212204
• 负责人: Thomas Sharkey
• 金额: $ 39.01万
• 依托单位: University of Wisconsin-Madison
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-08-01 至 2006-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0212204&HistoricalAwards=false
• 关键词: Molecular; Regulation; Capacity; Isoprene; Synthesis

Isoprene is emitted from many plants, especially trees. Isoprene emission has large effects on atmospheric chemistry and so its emission has been extensively studied but mechanisms of regulation of the rate of emission have not yet been determined. Isoprene emission from plants varies substantially with temperature and light. Experiments are proposed to test several hypotheses about how the rate of isoprene emission from plants is regulated. Short term regulation will be studied by measuring metabolites before, during, and after a change in light or temperature. The factors that control the instantaneous rate of isoprene emission will be assessed by analyzing (1) changes in metabolite levels during transients and (2) responses to feeding intermediates of the isoprene synthesis pathway. To keep track of isoprene coming from endogenous photosynthesis metabolites and that coming from exogenous intermediates, a laser-based photoacoustic system for detecting deuterium labeled isoprene from deuterated intermediates will be used by colleagues at the University of Bonn. Longer term induction phenomena will be studied in (1) leaves that have never made isoprene and in (2) leaves where the isoprene emission capacity has been reduced by moving the plants into low temperature and low light. Changes in precursor metabolite levels, enzyme activity, and transcript abundance for selected enzymes of the isoprene synthesis pathway will be included in the analysis. Finally, the steps required for the evolution of the capacity for isoprene emission will be studied. This will involve two approaches. First, isoprene synthase from the legume kudzu will be transformed into Arabidopsis on a constitutive promoter, on its own promoter, and on a heat-shock promoter. The regulation of the expression and activity of isoprene synthase and other selected genes in the isoprene synthesis pathway will be assessed to determine if non-emitting plants normally have the regulatory mechanisms needed for light and heat-dependent isoprene emission. Second, the differences between isoprene synthase and a similar sesquiterpene synthase will be determined by analyzing the crystal structure of isoprene synthase. These studies will provide basic information on regulation of isoprene synthesis to allow for altering isoprene synthesis by plants. It may be desirable to engineer plants or bacteria to make economically useful amounts of isoprene or it might be useful to engineer trees used in tree farming so that they do not produce isoprene. These studies will also be used to help predict isoprene emission from plants, which will improve our ability to predict atmospheric ozone production

异戊二烯是从许多植物中发出的，尤其是树木。异戊二烯的发射对大气化学具有很大的影响，因此已经对其发射进行了广泛的研究，但是尚未确定发射速率调节的机制。植物的异戊二烯发射随温度和光的差异很大。提出了实验来检验有关如何调节植物异戊二烯发射速率的几种假设。短期调节将通过在光或温度变化之前，期间和之后测量代谢产物来研究短期调节。控制异戊二烯发射瞬时速率的因素将通过分析（1）瞬态期间代谢物水平的变化以及（2）对异戊二烯合成途径的喂养中间体的反应。为了跟踪来自内源光合作用代谢产物的异戊二烯，以及来自外源性中间体的异戊二烯，这是一种基于激光的光声系统，用于检测来自氘代中间体的依非属的异戊二烯。长期诱导现象将在（1）从未制成异戊二烯的叶子中进行研究，在（2）叶中，通过将植物移入低温和低光，使异戊二烯排放能力降低。分析中将包括异戊二烯合成途径选定酶的前体代谢产物水平，酶活性和转录物丰度的变化。最后，将研究异戊二烯排放能力的演变所需的步骤。这将涉及两种方法。首先，来自豆科氏菌的异戊二烯合酶将在本构启动子，自身启动子和热震动剂启动子上转变为拟南芥。将评估异戊二烯合酶和其他选定基因的表达和活性的调节，以确定非发射植物是否通常具有光和热依赖性异戊二烯排放所需的调节机制。其次，异戊二烯合酶与类似倍半萜合酶之间的差异将通过分析异戊二烯合酶的晶体结构来确定。这些研究将提供有关异戊二烯合成调节的基本信息，以改变植物的异戊二烯合成。工程植物或细菌可能需要经济上有用的异戊二烯，或者对于在树耕作中使用的工程树来说可能是有用的，因此它们不产生异戊二烯可能是有用的。这些研究还将用于帮助预测植物的异戊二烯排放，这将提高我们预测大气臭氧产生的能力