SummaryThe interaction dynamics of homologous chromosomes during meiosis, such as recognition, pairing, synapsis, recombination, and segregation are vital for species fertility and genetic diversity within populations. Meiotic crossover (CO), a prominent feature of meiosis, ensures the faithful segregation of homologous chromosomes and enriches genetic diversity within a population. Nevertheless, visually distinguishing homologous chromosomes and COs remains an intractable challenge in cytological studies, particularly in non‐model or plants with small genomes, limiting insights into meiotic dynamics. In the present study, we developed a robust and reliable enhanced haplotype oligo‐painting (EHOP) technique to image small amounts of oligos, enabling visual discrimination of homologous chromosomes. Using EHOP developed based on sequence polymorphisms and reconstructed oligonucleotides, we visually distinguished parental and most recombinant chromosomes in cucumber F1 hybrids and F2 populations. Results from EHOP revealed that meiotic CO events preferentially occur in the 30–60% intervals of chromosome arms with lower sequence polymorphisms and significant recombination bias exists between cultivated and ancestral chromosomes. Due to the occupation of extensive heterochromatin occupancy, it is not yet possible to precisely identify the meiotic COs present in the central portion of chr2 and chr4. Notably, CO accessibility was universally detected in the cytological centromere region in F2 populations, a feature rarely observed in crops with large genomes. EHOP demonstrated exceptional performance in distinguishing homologous chromosomes and holds significant potential for broad application in studying homologous chromosome interactions.

中文翻译：

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使用增强的单倍型寡核苷酸绘画对黄瓜中的同源染色体进行差异可视化，揭示减数分裂交叉


摘要减数分裂过程中同源染色体的相互作用动力学，如识别、配对、突触、重组和分离，对于种群内的物种繁殖和遗传多样性至关重要。减数分裂交叉 （CO） 是减数分裂的一个突出特征，可确保同源染色体的忠实分离并丰富种群内的遗传多样性。然而，在细胞学研究中，视觉区分同源染色体和 CO 仍然是一个棘手的挑战，尤其是在非模型或基因组较小的植物中，限制了对减数分裂动力学的了解。在本研究中，我们开发了一种强大而可靠的增强型单倍型寡核苷酸绘画 （EHOP） 技术来对少量寡核苷酸进行成像，从而能够对同源染色体进行视觉区分。使用基于序列多态性和重建寡核苷酸开发的 EHOP，我们在黄瓜 F1 杂交种和 F2 群体中直观地区分了亲本和大多数重组染色体。EHOP 的结果表明，减数分裂 CO 事件优先发生在序列多态性较低的染色体臂的 30-60% 区间内，并且培养染色体和祖先染色体之间存在显着的重组偏倚。由于占据了广泛的异染色质，目前还无法精确识别存在于 chr2 和 chr4 中心部分的减数分裂 CO。值得注意的是，在 F2 种群的细胞学着丝粒区域中普遍检测到 CO 可及性，这一特征在具有大基因组的作物中很少观察到。EHOP 在区分同源染色体方面表现出卓越的性能，在研究同源染色体相互作用方面具有广泛的应用潜力。