Lepri Andrea, Kazmi Hira, Bertolotti Gaia, Longo Chiara, Occhigrossi Sara, Quattrocchi Luca, De Vivo Mirko, Scintu Daria, Svolacchia Noemi, Tarkowska Danuse, Tureckova Veronika, Strnad Miroslav, Del Bianco Marta, Di Mambro Riccardo, Costantino Paolo, Sabatini Sabrina, Dello Ioio Raffaele, Vittorioso Paola
Department of Biology and Biotechnology Charles Darwin, University of Rome, Sapienza, P. le Aldo Moro 5, 00185 Rome, Italy.
Department of Biology and Biotechnology Charles Darwin, Sapienza, via dei Sardi, 70, 00185 Rome, Italy.
Plant Commun. 2025 Apr 14;6(4):101262. doi: 10.1016/j.xplc.2025.101262. Epub 2025 Jan 28.
Plants have evolved several strategies to cope with the ever-changing environment. One example of this is given by seed germination, which must occur when environmental conditions are suitable for plant life. In the model system Arabidopsis thaliana seed germination is induced by light; however, in nature, seeds of several plant species can germinate regardless of this stimulus. While the molecular mechanisms underlying light-induced seed germination are well understood, those governing germination in the dark are still vague, mostly due to the lack of suitable model systems. Here, we employ Cardamine hirsuta, a close relative of Arabidopsis, as a powerful model system to uncover the molecular mechanisms underlying light-independent germination. By comparing Cardamine and Arabidopsis, we show that maintenance of the pro-germination hormone gibberellin (GA) levels prompt Cardamine seeds to germinate under both dark and light conditions. Using genetic and molecular biology experiments, we show that the Cardamine DOF transcriptional repressor DOF AFFECTING GERMINATION 1 (ChDAG1), homologous to the Arabidopsis transcription factor DAG1, is involved in this process functioning to mitigate GA levels by negatively regulating GA biosynthetic genes ChGA3OX1 and ChGA3OX2, independently of light conditions. We also demonstrate that this mechanism is likely conserved in other Brassicaceae species capable of germinating in dark conditions, such as Lepidium sativum and Camelina sativa. Our data support Cardamine as a new model system suitable for studying light-independent germination studies. Exploiting this system, we have also resolved a long-standing question about the mechanisms controlling light-independent germination in plants, opening new frontiers for future research.
植物已经进化出多种策略来应对不断变化的环境。种子萌发就是一个例子，它必须在环境条件适合植物生长时发生。在模式植物拟南芥中，种子萌发是由光诱导的；然而，在自然界中，几种植物的种子无论有无这种刺激都能萌发。虽然光诱导种子萌发的分子机制已得到充分了解，但控制黑暗中种子萌发的机制仍然模糊不清，主要是由于缺乏合适的模式系统。在这里，我们利用与拟南芥亲缘关系较近的碎米荠作为一个强大的模式系统，来揭示光不依赖型种子萌发的分子机制。通过比较碎米荠和拟南芥，我们发现维持促进萌发的激素赤霉素（GA）水平能促使碎米荠种子在黑暗和光照条件下都能萌发。利用遗传学和分子生物学实验，我们发现与拟南芥转录因子DAG1同源的碎米荠DOF转录抑制因子DOF影响萌发1（ChDAG1）参与了这一过程，它通过独立于光照条件负调控GA生物合成基因ChGA3OX1和ChGA3OX2来降低GA水平。我们还证明，这种机制可能在其他能够在黑暗条件下萌发的十字花科物种中保守，如独行菜和亚麻荠。我们的数据支持碎米荠作为一个适合研究光不依赖型种子萌发的新模型系统。利用这个系统，我们还解决了一个关于植物光不依赖型种子萌发控制机制的长期问题，为未来的研究开辟了新的前沿领域。
