Am J Bot. 1997 Nov;84(11):1588.
Evolution and maintenance of male sterility in seed plants can be explained by the maternal inheritance of mitochondria, which encode the trait, and by adaptive functions that enhance female fecundity in male-sterile compared to hermaphrodite individuals. Protogyny and male sterility can independently decrease the negative effect of pollen-pistil interference in self-incompatible species. In Plantago maritima, which possesses both traits, protogyny increases seed set in hermaphrodite individuals. This is shown both by a significantly positive association between seed set and retarded dehiscence of the anthers and by a more than 50% reduction in seed set following self-pollination. Male sterility does not seem to increase seed set further, as female and hermaphrodite plants do not differ significantly in mean seed set per capsule. Bagging experiments demonstrate strong self-incompatibility in the study populations. Hence, in P. maritima male sterility seems neither to prevent selfing nor to reduce the effect of pollen-pistil interference. Females had significantly larger stigmas than hermaphrodites, but seed set varied negatively with stigma length among females, indicating that the evolution of unisexuality in P. maritima is not due to prefertilization sex allocation. I therefore conclude that the genetical system of nucleocytoplasmic determination of gender is the main cause for maintenance of male sterility in P. maritima.
种子植物中雄性不育的进化和维持可以用线粒体的母系遗传来解释，线粒体编码这种特征，以及适应功能，这些功能可以增强雄性不育个体相对于雌雄同体个体的雌性繁殖力。雌雄异熟和雄性不育可以独立降低自交不亲和物种中花粉-柱头干扰的负面影响。在同时具有这两种特征的车前草中，雌雄异熟会增加雌雄同体个体的结实率。这表现在两个方面：一是花粉囊开裂延迟与结实率呈显著正相关，二是自交后结实率降低 50%以上。雄性不育似乎并没有进一步增加结实率，因为雌性和雌雄同体植物在每个蒴果的平均结实率方面没有显著差异。套袋实验证明了研究群体中的强自交不亲和性。因此，在车前草中，雄性不育似乎既不能阻止自交，也不能降低花粉-柱头干扰的影响。雌性的柱头明显大于雌雄同体，但在雌性中，结实率与柱头长度呈负相关，表明车前草中两性的进化不是由于受精前的性别分配。因此，我得出结论，核质决定性别遗传系统是车前草中雄性不育维持的主要原因。
