Department of Chromosome Biology, Max Planck Institute for Plant Breeding Research, 50829 Cologne, Germany.
Institut Jean-Pierre Bourgin, INRAE, AgroParisTech, Université Paris-Saclay, 78000 Versailles, France.
Proc Natl Acad Sci U S A. 2021 Mar 23;118(12). doi: 10.1073/pnas.2023613118.
Meiotic crossovers (COs) have intriguing patterning properties, including CO interference, the tendency of COs to be well-spaced along chromosomes, and heterochiasmy, the marked difference in male and female CO rates. During meiosis, transverse filaments transiently associate the axes of homologous chromosomes, a process called synapsis that is essential for CO formation in many eukaryotes. Here, we describe the spatial organization of the transverse filaments in (ZYP1) and show it to be evolutionary conserved. We show that in the absence of ZYP1 ( null mutants), chromosomes associate in pairs but do not synapse. Unexpectedly, in absence of ZYP1, CO formation is not prevented but increased. Furthermore, genome-wide analysis of recombination revealed that CO interference is abolished, with the frequent observation of close COs. In addition, heterochiasmy was erased, with identical CO rates in males and females. This shows that the tripartite synaptonemal complex is dispensable for CO formation and has a key role in regulating their number and distribution, imposing CO interference and heterochiasmy.
减数分裂交叉（CO）具有有趣的图案形成特性，包括 CO 干扰、CO 在染色体上良好间隔的趋势，以及雌雄 CO 率的显著差异的异配性。在减数分裂过程中，横向丝瞬时关联同源染色体的轴，这一过程称为联会，这对于许多真核生物中的 CO 形成是必不可少的。在这里，我们描述了 （ZYP1）中的横向丝的空间组织，并表明它具有进化保守性。我们表明，在没有 ZYP1（缺失突变体）的情况下，染色体成对关联，但不进行联会。出乎意料的是，在没有 ZYP1 的情况下，CO 的形成并没有被阻止，反而增加了。此外，对重组的全基因组分析表明，CO 干扰被消除，经常观察到紧密的 CO。此外，异配性被抹去，雌雄 CO 率相同。这表明三部分联会复合体对于 CO 的形成是可有可无的，并且在调节其数量和分布方面起着关键作用，施加 CO 干扰和异配性。
