The Population Genetics of Mitochondrial Heteroplasmy in a Gynodioecious Plant

除了核染色体上携带的大多数基因外，植物和动物的线粒体中还携带有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 lowgaris的研究表明，mtDNA有时是从母亲和父亲那里遗传的，导致后代中mtDNA分子的异质性混合(异质性)。本研究将在温室条件下，通过普通链霉菌的实验杂交，调查mtDNA的非母体遗传频率，并利用分子生物学的工具，记录自然种群中异质性的频率和程度。由于mtDNA在许多类型的研究中都被用作遗传标记，因此，在母本遗传的假设下，这一结果将对种群生物学家具有价值。这一假设只在相对较少的物种中得到了直接测试，而且非母系遗传的后果还没有被很好地理解。这一结果也将引起应用生物学家的兴趣，他们的目标是培育出具有重要经济意义的植物品系，这些植物品系产生高比例的雌性用于育种目的，因为植物的性别决定通常可追溯到线粒体基因。

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.