The Population Genetics of Mitochondrial Heteroplasmy in a Gynodioecious Plant

植物和动物除了核染色体上携带的大多数基因外，还携带线粒体中的DNA。在开花植物中，线粒体DNA （mtDNA）通常只从母亲那里遗传，因此个体内的mtDNA拷贝是相同的。最近对植物Silene vulgaris的研究表明，mtDNA的遗传有时来自母亲和父亲，导致后代mtDNA分子的异质性混合（heteroplasmy）。本研究将利用分子生物学的工具，通过在温室中进行的实验杂交，研究普通葡萄mtDNA的非母系遗传频率，并记录自然群体中异质性的频率和大小。这一结果将对种群生物学家有价值，因为mtDNA在许多类型的研究中被用作遗传标记，假设是母系遗传。这一假设只在相对较少的物种中得到了直接检验，非母系遗传的后果也没有得到很好的理解。这些结果也会引起应用生物学家的兴趣，他们的目标是开发具有经济价值的植物品系，这些植物在繁殖过程中产生高比例的雌性，因为植物的性别决定通常可以追溯到线粒体基因。

Plants and animals carry DNA in their mitochondria, in addition to the majority of genes that are carried on nuclear chromosomes. In flowering plants the mitochondrial DNA (mtDNA) is often inherited from the mother only, such that the copies of mtDNA within an individual are identical. Recent studies of the plant Silene vulgaris showed that inheritance of mtDNA is sometimes from both the mother and father, resulting in a heterogeneous mix of mtDNA molecules in the offspring (heteroplasmy). This study will investigate the frequency of non-maternal inheritance of mtDNA through experimental crosses of S. vulgaris conducted in the greenhouse, and document the frequency and magnitude of heteroplasmy in natural populations, using the tools of molecular biology.The results will be of value to population biologists because mtDNA is used as a genetic marker in many types of studies, under the assumption of maternal inheritance. This assumption has only been tested directly in relatively few species, and the consequences of non-maternal inheritance are not well understood. The results will also interest applied biologists whose goal is to develop lines of economically important plants that produce a high proportion of females for breeding purposes, given that sex determination in plants is often traced to mitochondrial genes.