Collaborative Research: Paternal Transmission and Recombination of the Mitochondrial Genome in the Plant Genus Silene

这个研究项目将扩大我们对植物中一种不寻常的遗传形式的原因和后果的理解，即通过花粉传递细胞器。细胞核细胞的一个决定性特征是存在具有独立基因组的细胞器。核基因组通常遗传自双亲。相比之下，细胞器的基因组，比如线粒体的基因组，几乎总是只从母亲那里遗传。然而，我们对偏离这一普遍规律的频率和原因知之甚少。因此，了解细胞器基因组的遗传对于理解进化过程非常重要。本项目将以植物Silene vulgaris为模型系统，探讨核基因组的地理起源与父系线粒体遗传的关系，以及线粒体基因组的物理结构与线粒体基因重组倾向的关系。这需要1)对几个寻常金貂线粒体基因组进行测序，以记录基因组结构并确定用于研究重组的遗传标记；2)对自然种群中的个体进行基因分型，以估计重组；3)在不同核基因型和线粒体基因型的个体之间进行实验杂交；4)对其后代进行基因分型，以确定线粒体父系遗传的发生率。除了进一步了解植物线粒体基因组生物学的基础知识外，研究结果应具有应用意义。植物育种家关注开发细胞质雄性不育资源，因为雄性不育个体在育种计划中的利用可以提高效率，而且CMS基因通常存在于线粒体基因组中。由于担心基因从转基因生物中逃逸，对细胞器基因组遗传的研究也很有价值。

This research project will expand our understanding of the causes and consequences of an unusual form of inheritance in plants, the transmission of organelles through pollen. A defining feature of cells with nuclei is the existence of organelles that have separate genomes. The nuclear genome is generally inherited from two parents. By contrast, the genomes of organelles, such as those in mitochondria, are nearly always inherited from the mother only. However, we know little about the frequency and cause of deviations from this general rule. Understanding the inheritance of organelle genomes is therefore important for understanding evolutionary processes. Using the plant Silene vulgaris as a model system, this project will explore the relationship between the geographic origins of the nuclear genome and paternal mitochondrial transmission, and the relationship between the physical structure of the mitochondrial genome and the propensity for mitochondrial genes to recombine, will be studied. This requires 1) sequencing several S. vulgaris mitochondrial genomes to document genome structure and identify genetic markers used to study recombination, 2) genotyping individuals from natural populations in order to estimate recombination, 3) conducting experimental crosses between individuals of varying nuclear and mitochondrial genotypes, and 4) genotyping their offspring to identify incidences of mitochondrial paternal inheritance. In addition to furthering fundamental knowledge of plant mitochondrial genome biology, the results should be of applied significance. Plant breeders are concerned with developing CMS (cytoplasmic male sterility) resources because utilization of male-sterile individuals in breeding programs increases efficiency, and CMS genes usually reside in the mitochondrial genome. Studies of the inheritance of organellar genomes are also valuable because of concerns about gene escape from genetically modified organisms.