Mitochondrial Factors Associated With Pollen Development

高等真核生物正在解决的一些最有趣的问题涉及到特定发育阶段的基因表达调控，这涉及到亚细胞细胞器之间的通信。已建立的细胞质雄性不育菜豆模式系统为解决这些问题提供了理想的遗传材料。该系统有许多独特的功能。已经鉴定出两种不同的核-线粒体遗传相互作用，它们导致了花粉表型的改变。证据表明，这种细胞器间相互作用的至少某些方面是受发育调节的。这项研究的重点是与花粉发育异常相关的线粒体序列，命名为pvs。该项目包括开发针对pVS内两个开放阅读框架的假定产物的抗体。这些抗体将表征两种预测的线粒体产物在核基因Fr存在时的表达。FR导致pVS序列与周围的线粒体区域一起消除。第二个核基因Fr2被预测会改变pv的表达。Fr和F2都恢复了正常的花粉发育。这些实验将包括Western印迹分析、免疫沉淀、原位回交和F2群体、细胞质雄性不育系、一些自发的细胞质可育回突变体和一个正常对照系。这项拟议的研究还将包括线粒体pvs区域转录的特征。这些实验将表征线粒体序列的发育表达，以响应两个改变花粉发育的不同核基因。这些实验还将确定这个线粒体序列中的潜在调控位点。

Some of the most interesting questions being addressed in higher eukaryotic organisms concern the regulation of gene expression at particular stages of development that involve communication between subcellular organelles. The model system that has been developed in cytoplasmic male sterile common bean provides ideal genetic materials to address these questions. The system has a number of unique features. Two distinct nuclear-mito- chondrial genetic interactions have been identified that result in an altered pollen phenotype. Evidence suggests that at least some aspects of this interorganellar interaction are developmentally regulated. The focus of this study is a mitochondrial sequence, designated pvs, associated with abnormal pollen development. The project includes development of antibodies against the putative products of two open reading frames within pvs. These antibodies will characterize the expression of the two predicted mitochondrial products in response to the presence of nuclear gene Fr. Fr results in the elimination of the pvs sequence together with the surrounding mitochondrial region. A second nuclear gene, Fr2, is predicted to alter expression of pvs. Both Fr and Fr2 restore normal pollen development. The experiments will include Western blot analysis, immunoprecipitations, and in situ backcross and F2 populations, the cytoplasmic male sterile line, a number of spontaneous cytoplasmic fertile revertants, and a normal control line. The proposed research will also include characterization of transcription of the mitochondrial pvs region. The experiments will characterize the developmental expression of a mitochondrial sequence in response to two distinct nuclear genes that alter pollen development. The experiments will also identify potential regulatory sites within this mitochondrial sequence.