Regulation of the Capacity for Isoprene Synthesis in Kudzu

摘要本研究的总体目标是了解异戊二烯释放量巨大的外来入侵杂草葛根的释放能力是如何调控的。异戊二烯对环境的影响很大，因为它有助于“近地”臭氧的形成和光化学烟雾。无论从光合产物转化为异戊二烯的比例还是从进入大气的碳氢化合物比例来看，异戊二烯的合成都是一个主要的生化途径。研究异戊二烯的排放是及时而重要的，因为异戊二烯的生物合成在碳通量方面仅次于光合固碳。最近的数据表明，除了速率的短期变化外，异戊二烯排放能力也有较长期（6-48小时）的变化。本研究将对异戊二烯合成能力长期调控的分子和生化基础进行研究。异戊二烯是由最近描述的磷酸脱氧纤维素（DXP）途径产生的。尽管拟南芥不是一种释放异戊二烯的植物，但这一途径的两种酶现在已经在拟南芥中克隆出来。这些基因序列将被用来制作探针来测量这些酶在诱导和非诱导条件下的信息水平。这些蛋白也将在大肠杆菌中表达，这样抗体就可以用于western blots。将尝试克隆异戊二烯合成酶，以便也可以研究这种酶的调节。这些信息将用于确定当异戊二烯排放能力发生变化时，DXP途径发生何种调节，以及哪些变化可能调节异戊二烯排放能力。

Sharkey Award AbstractThe overall goal of this research is to understand how the capacity for isoprene emission is regulated in Kudzu, an invasive weed which emits huge amounts of isoprene. Isoprene has a great impact on the environment because it contributes to the "near-ground" ozone formation and photochemical smog. Isoprene synthesis is a major biochemical pathway both in terms of the proportion of photosynthate converted to isoprene and in terms of the proportion of hydrocarbon entering the atmosphere. Studying isoprene emission is timely and important because isoprene biosynthesis is second only to photosynthetic carbon fixation in terms of carbon flux. Recent data indicate that in addition to short-term changes in rate, there is a longer-term (6-48 hours) change in the capacity for isoprene emission. In this research the molecular and biochemical basis of this longer-term regulation of the capacity for isoprene synthesis will be studied. Isoprene is made by the recently described deoxyxylulose phosphate (DXP) pathway. Two of the enzymes of this pathway have now been cloned in Arabidopsis even though Arabidopsis is not an isoprene emitting plant. These gene sequences will be used to make probes to measure message level for those enzymes in inductive and noninductive conditions. These proteins will also be expressed in E. coli so that antibodies can be made for use with western blots. Attempts will be made to clone isoprene synthase so that the regulation of this enzyme can also be studied. This information will be used to determine what regulation of the DXP pathway occurs when isoprene emission capacity changes and which changes likely regulate the capacity for isoprene emission.