Chen Junlin, Zhang Minyan, Zhang Qing, Hou Xianfei, Jia Donghai, Gu Yuanguo, Wan Heping, Zhao Hu, Wen Jing, Yi Bin, Fu Tingdong, Shen Jinxiong, Zhao Lun
National Key Laboratory of Crop Genetic Improvement, National Engineering Research Center of Rapeseed, Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan, 430070, China.
Crop Research Institute, Xinjiang Academy of Agricultural Sciences, Urumqi, 830091, China.
New Phytol. 2025 Nov;248(3):1475-1490. doi: 10.1111/nph.70532. Epub 2025 Sep 6.
Heterosis holds great potential for improving yield, quality, and environmental adaptability in crop breeding, which suggests that hybrids can exhibit better performance in adapting to extreme environments. However, the epigenetic mechanisms of salt-tolerant heterosis in allopolyploid crop Brassica napus (AACC, 2n = 38), particularly chromatin accessibility, remain largely unexplored. We investigated the dynamics of chromatin accessibility and transcriptional reprogramming during a time course of salt exposure in Brassica napus hybridization. We observed the importance of epigenetic and transcriptional regulation in plant resilience. The chromatin accessibility and transcriptome rapidly changed within a short time frame of salt exposure. Hybrid possessed more accessible chromatin and more active transcriptome than that of parents driven by epigenetic aggregation and genetic complementation. Broader and more flexible genomic resources enabled hybrid preferentially unitized advantageous alleles for salt stress adaptation. Meanwhile, these salt stress-responsive genes in hybrid exerted various heterotic effects, with non-additive genetic effects, including full-dominance, partial-dominance, and overdominance effects, playing a crucial role in salt stress adaptation. Our results expanded the heterosis hypothesis from an epigenetic perspective and emphasized how the combined effects of genetic and epigenetic factors enable hybrid to better withstand salt stress.
杂种优势在作物育种中对于提高产量、品质和环境适应性具有巨大潜力，这表明杂种在适应极端环境方面可能表现出更好的性能。然而，异源多倍体作物甘蓝型油菜（AACC，2n = 38）耐盐杂种优势的表观遗传机制，尤其是染色质可及性，在很大程度上仍未得到探索。我们研究了甘蓝型油菜杂交过程中盐胁迫处理时间进程内染色质可及性和转录重编程的动态变化。我们观察到表观遗传和转录调控在植物抗性中的重要性。在盐胁迫处理的短时间内，染色质可及性和转录组迅速发生变化。由于表观遗传聚集和遗传互补作用，杂种比亲本拥有更易接近的染色质和更活跃的转录组。更广泛、更灵活的基因组资源使杂种能够优先利用有利等位基因来适应盐胁迫。同时，杂种中这些盐胁迫响应基因发挥了各种杂种优势效应，其中非加性遗传效应，包括完全显性、部分显性和超显性效应，在盐胁迫适应中起关键作用。我们的结果从表观遗传学角度扩展了杂种优势假说，并强调了遗传和表观遗传因素的综合作用如何使杂种更好地耐受盐胁迫。
