Shenzhen Branch, Guangdong Laboratory of Lingnan Modern Agriculture, Key Laboratory of Synthetic Biology, Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, China.
State Key Laboratory of Tibetan Plateau Earth System, Environment and Resources (TPESER), Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101, China.
Mol Biol Evol. 2024 Jul 3;41(7). doi: 10.1093/molbev/msae132.
Segregation distorters (SDs) are genetic elements that distort the Mendelian segregation ratio to favor their own transmission and are able to spread even when they incur fitness costs on organisms carrying them. Depending on the biology of the host organisms and the genetic architecture of the SDs, the population dynamics of SDs can be highly variable. Inbreeding is considered an effective mechanism for inhibiting the spread of SDs in populations, and can evolve as a defense mechanism against SDs in some systems. However, we show that inbreeding in the form of selfing in fact promotes the spread of SDs acting as pollen killers in a toxin-antidote system in hermaphroditic plants by two mechanisms: (i) By reducing the effective recombination rate between killer and antidote loci in the two-locus system and (ii) by increasing the proportion of SD alleles in individual flowers, rather than in the general gene-pool. We also show that in rice (Oryza sativa L.), a typical hermaphroditic plant, all molecularly characterized SDs associated with pollen killing were involved in population hybridization and have introgressed across different species. Paradoxically, these loci, which are associated with hybrid incompatibility and can be thought of as Bateson-Dobzhansky-Muller incompatibility loci are expected to reduce gene-flow between species, in fact cross species boundaries more frequently than random loci, and may act as important drivers of introgression.
分离干扰因子（SDs）是一类遗传因子，它们能改变孟德尔分离比，使其有利于自身的传递，即便在携带它们的生物身上会产生适应性代价，它们也能传播。根据宿主生物的生物学特性和 SDs 的遗传结构，SDs 的种群动态可能高度多变。近交被认为是抑制 SDs 在种群中传播的有效机制，在某些系统中，它可以作为针对 SDs 的防御机制进化而来。然而，我们发现，自交形式的近交实际上促进了作为毒素-解毒剂系统中花粉杀手的 SDs 的传播，这是通过两种机制实现的：（i）通过降低双基因座系统中杀手和解毒基因座之间的有效重组率，（ii）通过增加个体花朵中 SD 等位基因的比例，而不是在一般基因库中。我们还表明，在典型的雌雄同体植物水稻（Oryza sativa L.）中，所有与花粉杀伤有关的分子特征明确的 SDs 都参与了种群杂交，并在不同物种间渗入。矛盾的是，这些与杂种不育相关的基因座，可被视为贝茨on-Dobzhansky-Muller 不相容性基因座，它们预计会减少物种间的基因流动，但实际上比随机基因座更频繁地跨越物种界限，并且可能是基因渗入的重要驱动因素。
