Li Xiaoying, Liu Yue, Xie Zhengqing, Tian Baoming, Datta Tanusree, Yuan Yuxiang, Wei Xiaochun, Wei Fang, Shi Gongyao
Henan International Joint Laboratory of Crop Gene Resources and Improvements, School of Agricultural Sciences, Zhengzhou University, Zhengzhou, 450001, China.
Institute of Vegetables, Henan Academy of Agricultural Sciences, Zhengzhou, 450002, Henan, China.
Plant Cell Rep. 2025 Jun 28;44(7):158. doi: 10.1007/s00299-025-03533-7.
Varying rates in chromosome pairing, chromosomal fragmentation and chromosome loss during meiosis, indicates homologous recombination pathway of DNA damage repair was challenged to different degrees in three Brassica hybrid allodiploids. Sequence similarity of combined genomes in plant hybrid species can shape chromosome pairing and synapsis during meiosis, but the extent remains unclear. The present study investigated meiotic chromosomal behaviors in three typical Brassica hybrid allodiploids (AB, AC and BC) as models with the evolutionarily related genomes from B. rapa (AA), B. nigra (BB) and B. oleracea (CC). The results showed that chromosome allosyndesis occurred at the pachytene with the varying rate and led to different frequencies of univalents, bivalents, and multivalents, and finally caused the imbalanced segregation with retard chromosomes in daughter cells during meiosis in allodiploids AB, AC and BC. Notably, allodiploid AC displayed an increased incidence of bivalent formation, chromosome bridges, and chromosomal fragmentation. Conversely, allodiploid BC was prone to chromosome loss, particularly within the C genome, and exhibited the highest frequency of lagging chromosomes, resulting in micronuclei and spindle disarray. Transcriptomic analysis revealed that in allodiploid AC the up-regulated genes were predominantly involved in synapsis (ASY1, RBR1), microtubule assembly (AUG4, AUG5, AUG6), and DNA damage repair (BRCA1, BRCA2, FAS1) pathways. In contrast, genes related to DNA damage repair (PMS1, LIG4, ALT2) were mostly transcription-deficient in allodiploids AB and BC, predisposing these hybrids to extensive DNA damage and chromosome lag. Collectively, these findings underscore the profound impact of genomic combinations with sequence divergence on chromosom pairing during meiosis in plant hybrid species.
减数分裂过程中染色体配对、染色体片段化和染色体丢失的速率各不相同，这表明在三个芸薹属杂交异源二倍体中，DNA损伤修复的同源重组途径受到了不同程度的挑战。植物杂交物种中组合基因组的序列相似性可影响减数分裂过程中的染色体配对和联会，但具体程度尚不清楚。本研究以三个典型的芸薹属杂交异源二倍体（AB、AC和BC）为模型，研究其减数分裂染色体行为，这些异源二倍体的基因组与来自白菜（AA）、黑芥（BB）和甘蓝（CC）的基因组具有进化相关性。结果表明，染色体异源联会在粗线期以不同速率发生，导致单价体、二价体和多价体的频率不同，最终导致异源二倍体AB、AC和BC在减数分裂过程中，子细胞出现染色体分离不平衡和染色体滞后现象。值得注意的是，异源二倍体AC中二价体形成、染色体桥和染色体片段化的发生率增加。相反，异源二倍体BC容易发生染色体丢失，尤其是在C基因组内，并且滞后染色体的频率最高，导致微核和纺锤体紊乱。转录组分析表明，在异源二倍体AC中，上调基因主要参与联会（ASY1、RBR1）、微管组装（AUG4、AUG5、AUG6）和DNA损伤修复（BRCA1、BRCA2、FAS1）途径。相比之下，与DNA损伤修复相关的基因（PMS1、LIG4、ALT2）在异源二倍体AB和BC中大多转录不足，使这些杂交种易发生广泛的DNA损伤和染色体滞后。总的来说，这些发现强调了序列差异的基因组组合对植物杂交物种减数分裂过程中染色体配对的深远影响。
