Uniparental inheritance of mitochondrial and chloroplast genes: mechanisms and evolution.

In nearly all eukaryotes, at least some individuals inherit mitochondrial and chloroplast genes from only one parent. There is no single mechanism of uniparental inheritance: organelle gene inheritance is blocked by a variety of mechanisms and at different stages of reproduction in different species. Frequent changes in the pattern of organelle gene inheritance during evolution suggest that it is subject to varying selective pressures. Organelle genes often fail to recombine even when inherited biparentally; consequently, their inheritance is asexual. Sexual reproduction is apparently less important for genes in organelles than for nuclear genes, probably because there are fewer of them. As a result organelle sex can be lost because of selection for special reproductive features such as oogamy or because uniparental inheritance reduces the spread of cytoplasmic parasites and selfish organelle DNA.

几乎所有真核生物中，至少有部分个体仅从单一亲本处继承线粒体基因与叶绿体基因。单亲遗传（uniparental inheritance）并无统一机制：不同物种的细胞器基因遗传会被多种机制阻断，且阻断发生在生殖过程的不同阶段。细胞器基因遗传模式在演化过程中频繁发生改变，这提示其受到不同选择压力的影响。即便以双亲方式遗传，细胞器基因通常也无法发生重组；因此其遗传模式为无性遗传。相较于核基因，有性生殖对细胞器基因而言显然并非必需，这可能是因为细胞器基因的数量远少于核基因。因此，由于对卵式生殖（oogamy）等特殊生殖特征的选择，或是由于单亲遗传能够抑制细胞质寄生虫与自私细胞器DNA的传播，细胞器的有性生殖机制可能会丢失。