德国马克斯·普朗克植物育种研究所André Marques研究组取得一项新突破。他们提出了无杂交的性模拟了舌孢虫的无性系繁殖。相关论文于2026年9月16日发表在《自然》杂志上。

减数分裂重组通过在同源染色体之间产生交叉互换，确保染色体准确分离并促进遗传多样性。尽管在大多数有性生殖生物中必不可少，但重组受到不同程度的调控，并可能在某些谱系中缺失，这种情况称为无交叉互换。然而，一个有性物种雌雄双方均专性无交叉互换尚未被记录。在此，研究人员研究了 Rhynchospora tenuis，一种已知染色体数目最低且具有反向减数分裂的开花植物。结合基因组学与分子实验，研究人员表明，R. tenuis 在雄性和雌性减数分裂中均发生专性的全基因组无交叉互换。尽管早期减数分裂轴形成正常，但联会失败，细胞学和遗传学上均检测不到交叉互换，单价体在中期I持续存在。转座子的单倍型特异性积累产生分离扭曲，有利于较大、重复丰富的染色体的传递。尽管如此，有性生殖仍被保留：只有当易位兼容的配子相遇时，受精才产生可育种子，表明存在强烈的减数分裂后选择，淘汰不兼容的纯合组合。结果，所有存活后代在遗传上相同，通过有性生殖并恢复亲本基因型，有效维持了杂合性，模拟了克隆繁殖。研究人员提出，重组丧失、低染色体数目、反向减数分裂以及对兼容配子组合的选择共同使得尽管存在有性生殖，仍能实现忠实分离和类克隆遗传。这些发现模糊了性与克隆性之间的界限，将基因组结构、重组丧失和传递偏倚联系起来。

附：英文原文

Title: Sex without crossovers mimics clonal reproduction in Rhynchospora tenuis

Author: Zhang, Meng, Castellani, Marco, Steckenborn, Stefan, Majka, Maciej, Tsipas, Georgios, Nascimento, Thiago, Neumann, Ulla, Thangavel, Gokilavani, Robledillo, Laura A., Lux, Thomas, Debern, Lorraine, Pfordt, Ursula, Campoy, Jos A., Vijayan, Athul, Timmers, Ton, Sargheini, Nafiseh, Marek, Magdalena, Sun, Hequan, Hofstatter, Paulo G., Huettel, Bruno, Dreissig, Steven, Mayer, Klaus F. X., Figueiredo, Duarte D., Vanzela, Andr L. L., Schneeberger, Korbinian, Marques, Andr

Issue&Volume: 2026-09-16

Abstract: Meiotic recombination ensures accurate chromosome segregation and promotes genetic diversity by generating crossovers between homologous chromosomes1. Although essential in most sexually reproducing organisms, recombination is variably regulated and can be absent in some lineages, a condition known as achiasmy2. However, obligate achiasmy in both sexes of a sexual species has not been documented. Here we investigate Rhynchospora tenuis, a flowering plant with the lowest known chromosome number and inverted meiosis3. Combining genomics with molecular experiments, we show that R. tenuis undergoes obligate, genome-wide achiasmy in both male and female meiosis. Despite normal early meiotic axis formation, synapsis fails, crossovers are undetectable cytologically and genetically, and univalents persist at metaphase I. Haplotype-specific accumulation of transposable elements generates segregation distortion favouring the transmission of larger, repeat-rich chromosomes. Sexual reproduction is nevertheless retained: fertilization yields viable seeds only when translocation-compatible gametes meet, indicating strong post-meiotic selection against incompatible homozygous combinations. As a result, all surviving offspring are genetically identical, effectively maintaining heterozygosity by sexual reproduction with parental genotype restitution mimicking clonal reproduction. We propose that recombination loss, a low chromosome number, inverted meiosis and selection for compatible gamete combinations together enable faithful segregation and clonal-like inheritance despite sexual reproduction. These findings blur the boundary between sex and clonality, linking genome architecture, recombination loss and transmission bias.

DOI: 10.1038/s41586-026-11057-7

Source: https://www.nature.com/articles/s41586-026-11057-7