Mitochondrial/Nuclear Regulation of Respiration in Arabidopsis

线粒体有自己的基因组，然而，它们的大多数蛋白质是核编码的，这些蛋白质的表达和输入需要细胞器和细胞核之间高度调节的双向通信。迄今为止，在植物中分离出细胞核-细胞核通讯的元件还不可行。 缺失的成分是线粒体功能的一个容易评分的特征，一个对环境信号敏感的特征。 植物线粒体有一个分支的呼吸途径与交替氧化酶（AOX）不耦合质子转运和ATP合成。 寒冷、创伤、活性氧（ROS）和病原体攻击等都会增加交替氧化酶活性和Aox基因表达。在实验室中，AOX也是植物中的一种抗氧化活性，因此其水平可以通过遗传修饰和恢复缺乏AOX活性的潜在突变体来实现。 我们的研究集中在使用AOX表达来评分线粒体功能的线粒体-核信号传导中的突变体的分离。 我们设计了一个视觉屏幕受损AOX诱导后的挑战，氧化应激。为了补充这个屏幕，我们使用微阵列分析，以进一步表征突变体，并确定基因和基因簇参与应力诱导AOX表达。 拟南芥叶片线粒体基因表达的初步微阵列实验证实了这种方法是成功的。 [初始数据可在线获得：http：//genome www4.stanford.edu/MicroArray/SMD，实验者为“McIntosh”]为了确保基因组的完全覆盖，我们将使用寡核苷酸阵列、cDNA阵列和定向“线粒体”阵列。 与转基因植物结合的突变体将用于破译线粒体参与氧化应激信号传导和细胞死亡，以及AOX在低毒力反应中的作用。 AOX和ROS参与细胞死亡将通过细胞色素c基因家族（At-Cc）的表达，细胞色素c水平的细胞色素和胞质溶胶，和细胞色素途径的活性进行研究。

Mitochondria have their own genomes, however, the majority of their proteins are nuclear-encoded and the expression and import of these proteins requires a highly regulated, two-way communication between organelles and the nucleus. To date, it has not been feasible to isolate the elements of mitochondrion-nucleus communication in plants. The missing component has been an easily scorable trait for mitochondrial function, one responsive to environmental signals. Plant mitochondria have a branched respiratory pathway with an alternative oxidase (AOX) not coupled to proton translocation and ATP synthesis. Cold, wounding, Reactive Oxygen Species (ROS), and pathogen attack, among others, increase alternative oxidase activity and Aox gene expression. AOX, in the laboratory, is also a dispensable activity in plants, thus its levels may be genetically modified and potential mutants lacking AOX activity recovered. Our research is centered around the isolation of mutants in mitochondrion-nucleus signaling using AOX expression to score for mitochondrial function. We have devised a visual screen for impaired AOX induction after challenge by oxidative stress. To complement this screen, we use microarray analysis to further characterize the mutants, and to identify genes and gene clusters involved in stress-induced AOX expression. Preliminary microarray experiments on mitochondrial gene expression in Arabidopsis leaves establish that this approach can be successful. [Initial data are available online: http://genome www4.stanford.edu/MicroArray/SMD under experimenter "McIntosh"] To ensure complete coverage of the genome we will use oligoarrays, cDNA arrays and directed "mitochondrial" arrays. Mutants in conjunction with transgenic plants will be used to decipher mitochondrial involvement in oxidative stress signaling and cell death, and the role of AOX in the hypevirulence response. AOX and ROS involvement in cell death will be studied through cytochrome c gene family (At-Cc) expression, cytochrome c levels in the mitochondrion and cytosol, and cytochrome pathway activity.