Mitochondrial Factors Associated with Pollen Development

最近对核和线粒体基因组之间发生的遗传相互作用的研究表明，核提供的许多调节功能是高等植物所特有的。一类有用的线粒体突变，引起细胞质雄性不育表型，可用于研究这些不寻常的核-线粒体交换。我们计划利用普通豆细胞质雄性不育系统的有用特征来研究核基因型在线粒体基因组结构和表达调控中的作用，特别强调这些细胞内事件对花粉发育模式的重要性。在我们的研究过程中，我们计划追求两个主要目标。我们打算进一步表征与花粉不育相关的线粒体序列pvs的表达。我们已经开发了一个线粒体cDNA文库，这将使我们能够确定pvs的表达是否涉及转录物剪接，并鉴定从该区域转录的所有编码开放阅读框。我们有针对共转录的第二开放阅读框pvs-orf98产物的多克隆抗体。利用转录信息和这些抗体，我们将评估不育相关线粒体片段的时空表达。这将包括转录分析以及免疫细胞化学。我们的第二个目标将是评估两种不同的核育性恢复基因对pvs序列表达的影响。有了关于pvs转录的信息，以及抗pvs抗体的使用，我们将确定引入两种不同的核恢复基因的发育和表达后果。初步证据表明，pvs的表达及其调控仅限于植物生殖组织。***我们的最终目标将是利用本研究获得的信息来鉴定调节pvs序列表达的其他核基因。我们已经确定了我们实验室以前没有研究过的五个植物系，每个系都含有核育性恢复等位基因。利用这项研究的信息进行遗传和分子分析，将使我们能够确定这些核基因的作用机制是否与已经确定的两个CMS普通豆恢复基因Fr和Fr2不同。% % %

Mackenzie Abstract MCB-9316342 Recent research into the genetic interactions that occur between the nuclear and mitochondrial genomes suggests that a number of regulatory functions supplied by the nucleus are unique to higher plants. A useful class of mitochondrial mutants, giving rise to the cytoplasmic male sterility phenotype, is available for the study of these unusual nuclear-mitochondrial exchanges. We plan to take advantage of the useful features of the cytoplasmic male sterility system in common bean to investigate the role of nuclear genotype in the regulation of mitochondrial genome structure and expression, with particular emphasis on the importance of these intracellular events on the pattern of pollen development. During the course of our study, we plan to pursue two primary objectives. We intend to further characterize the expression of a mitochondrial sequence, pvs, that is associated with pollen sterility. We have developed a mitochondrial cDNA library that will allow us to determine whether the expression of pvs involves transcript splicing and to identify all encoded open reading frames transcribed from this region. We have available polyclonal antibodies against the product of a co-transcribed second open reading frame, pvs-orf98. With the transcription information and these antibodies, we will evaluate the temporal and spatial expression of the sterility-associated mitochondrial segment. This will include transcription assays as well as immunocytochemistry. Our second objective will be to evaluate the effects of two different nuclear fertility restorer genes on expression of the pvs sequence. With information gained regarding transcription of pvs, and with the use of anti-PVS antibodies, we will determine the developmental and expressional consequences of introducing the two different nuclear restorer genes. Preliminary evidence suggests that expression of pvs and its regulation are restricted to plant reproductive tissues. *** Ou r final objective will be to use the information derived from this study to identify additional nuclear genes that regulate expression of the pvs sequence. We have identified five plant lines not previously studied by our lab, each containing nuclear fertility restorer alleles. Genetic and molecular analysis using the information from this study will allow us to determine whether these nuclear genes act by mechanisms distinct from Fr and Fr2, two restorer genes already identified for CMS common bean. %%%