Data from: Genetic architecture of isolation between two species of Silene with sex chromosomes and Haldane's rule

Examination of the genetic architecture of hybrid breakdown can provide insight into the genetic mechanisms of commonly observed isolating phenomena such as Haldane’s rule. We used line-cross analysis to dissect the genetic architecture of divergence between two plant species that exhibit Haldane’s rule for male sterility and rarity, Silene latifolia and Silene diclinis. We made 15 types of crosses, including reciprocal F1, F2, backcrosses, and later-generation crosses, grew the seeds to flowering, and measured the number of viable ovules, proportion of viable pollen, and sex ratio. Typically, Haldane’s rule for male rarity in XY animal hybrids is explained by interactions involving recessive X-linked alleles that are deleterious when hemizygous (dominance theory), while sterility is explained by rapid evolution of spermatogenesis genes (faster-male evolution). In contrast, we found that the genetic mechanisms underlying Haldane’s rule between the two Silene species did not follow these conventions. Dominance theory was sufficient to explain male sterility, but male rarity likely involved faster-male evolution. We also found an effect of the neo-sex chromosomes of S. diclinis on the extreme rarity of some hybrid males. Our findings suggest that the genetic architecture of Haldane’s rule in dioecious plants may differ from those commonly found in animals.

对杂种衰败（hybrid breakdown）的遗传结构进行解析，可为霍尔丹法则（Haldane’s rule）这类常见生殖隔离现象的遗传机制提供研究洞见。本研究采用杂交系分析（line-cross analysis），对两种呈现雄性不育与雄性稀有性霍尔丹法则的植物物种——白玉草（Silene latifolia）与二性麦瓶草（Silene diclinis）——的分化遗传结构展开剖析。我们共设置15类杂交组合，涵盖正反交F1代、F2代、回交群体及后续世代杂交组合，将种子培育至开花阶段，随后测定了可存活胚珠数量、有活力花粉比例与性别比例。常规观点认为，XY型动物杂种中雄性稀有性的霍尔丹法则，可通过涉及半合子状态下有害隐性X连锁等位基因的互作来解释（即显性理论），而雄性不育则可通过精子发生基因的快速进化（快雄性进化理论）得以阐释。与之形成鲜明对比的是，本研究发现这两种蝇子草属物种间霍尔丹法则的遗传机制并未遵循上述常规模式：显性理论足以解释雄性不育现象，但雄性稀有性大概率与快雄性进化相关。我们还观测到，二性麦瓶草的新性染色体（neo-sex chromosomes）对部分杂交雄性的极端稀有性存在调控效应。本研究结果表明，雌雄异株植物（dioecious plants）中霍尔丹法则的遗传结构，或与常见于动物中的模式存在显著差异。