Nucleus-Cytoplasm Interactions : Molecular Analysis and Their Implication in Cron Improvement

植物细胞的正常功能需要三个遗传区室之间的协调：细胞核，质体和线粒体。我们非常不了解细胞核和线粒体遗传系统的活动是如何协调的。细胞质雄性不育（CMS）是研究细胞核-线粒体互作的一个很好的模型，在正常甜菜和CMS甜菜中发现了几个线粒体基因的转录差异。在这些基因中，只有coxl的转录模式受到核背景的影响。据报道，两个显性核基因（Rf 1和Rf 2）是恢复甜菜育性所必需的。为了确定在CMS和恢复植物之间观察到的coxl转录本差异是否与Rf基因的作用相关，我们分析了BC 1回交（rf 1 rf 1 rf 2 rf 2 * Rf 1 rf 1 Rf 2 rf 2）群体的个体中的coxl转录本。四个后代基因型，Rf 1 rf 1 Rf 2 rf 2（可育），Rf 1 rf 1 rf 2 rf 2（部分不育），rf 1 rf 1 Rf 2 rf 2（部分不育），和rf 1 rf 1 rf 2 rf 2（不育），并且这些应该以大约相等的数量出现。用cox 1探针对13个雄性可育和16个雄性不育后代的线粒体转录本进行了北方分析。结果表明，coxl基因转录本的差异是由于一个单一的核位点，并没有与Rf基因共分离。因此，甜菜coxl基因座提供了一个有吸引力的系统，通过核基因调节线粒体基因表达的机制进行研究。该项目还包括关于从线粒体或叶绿体基因组向核基因组转移基因的问题。

Correct functioning of a plant cell requires coordination between three genetic compartments : the nucleus, the plastids and the mitochondria. We are very kignorant of how the activities of the nuclear and mitochondrial genetic systems are coodinated. Cytoplasmic male sterility (CMS) provides a good model to investigate nuclear-mitochondrial interactions.Several mitochondrial genes were identified as exhibiting differences in transcript patterns between normal and CMS sugarbeet. Of these genes only the coxl transcript pattern is affected by nuclear background. Two dominant nuclear genes (Rf1 and Rf2) have been reported to be necessary to restore fertility in sugarbeet. To determine if the coxl transcript differences observed between CMS and restored plants are associated with the action of Rf genes, we have analyzed the coxl transcripts in individuals of a BC1 backcross (rf1rf1rf2rf2*Rf1rf1Rf2rf2) population. Four progeny genotypes are exprected, Rf1rf1Rf2rf2 (fertile), Rf1rf1rf2rf2 (partial sterile), rf1rf1Rf2rf2 (partial sterile), and rf1rf1rf2rf2 (sterile), and these should occur in about equal numbers. Northern analysis of mitochondrial transcripts of 13 male-fertile and 16 male-sterile progeny was performed using cox1 probe. The results showed that the coxl transcript differences were due to a single nuclear locus and did not cosegregate with Rf genes. The sugarbeet coxl locus thus offers an attractive system for studying the mechanisms through which nuclear genes regulate mitochondrial gene expression. This project also included the issue concerning the gene transfer from the mitochondrial or chloroplast genome to the nucleus genome.