Jing Hua, Liu Wei, Qu Gao-Ping, Niu De, Jin Jing Bo
Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China.
University of Chinese Academy of Sciences, Beijing, 100049, China.
New Phytol. 2025 Feb;245(3):1040-1055. doi: 10.1111/nph.20270. Epub 2024 Nov 19.
DELAY OF GERMINATION1 (DOG1) is a critical regulator of seed dormancy and seed thermoinhibition. However, how DOG1 expression is regulated by post-translational modifications and how seeds transmit the high-temperature signal to DOG1 remain largely unknown. ALFIN1-like 6/7 (AL6/7) was previously found to repress DOG1 expression during seed imbibition. Here, we found that AL6/7 represses seed dormancy partly by downregulating DOG1 expression. AtSIZ1, a SUMO E3 ligase, interacts with AL6 and mediates its SUMOylation mainly at the lysine 181 residue. SIZ1-mediated SUMOylation of AL6 is required for repression of DOG1 transcription and seed dormancy. SUMOylation of AL6 is required for its association with the DOG1 locus and protects it from ubiquitination and subsequent 26S proteasome-mediated protein degradation. High temperatures decrease SUMOylation levels of AL6, resulting in downregulation of AL6 protein levels and an increase in DOG1 transcription, which consequently causes reduced seed germination. Taken together, these results demonstrate that reversible SUMOylation of AL6 fine-tunes DOG1 expression, which is required for precise establishment of seed dormancy and inhibition of seed germination under high-temperature conditions in Arabidopsis thaliana.
种子萌发延迟1（DOG1）是种子休眠和种子热抑制的关键调节因子。然而，DOG1的表达如何受到翻译后修饰的调控，以及种子如何将高温信号传递给DOG1，目前仍 largely unknown。之前发现类ALFIN1 6/7（AL6/7）在种子吸胀过程中抑制DOG1的表达。在此，我们发现AL6/7部分通过下调DOG1的表达来抑制种子休眠。AtSIZ1是一种SUMO E3连接酶，与AL6相互作用并主要在赖氨酸181残基处介导其SUMO化。AL6的SIZ1介导的SUMO化是抑制DOG1转录和种子休眠所必需的。AL6的SUMO化是其与DOG1基因座结合所必需的，并保护其免受泛素化以及随后26S蛋白酶体介导的蛋白质降解。高温降低了AL6的SUMO化水平，导致AL6蛋白水平下调以及DOG1转录增加，从而导致种子萌发减少。综上所述，这些结果表明AL6的可逆SUMO化微调了DOG1的表达，这是拟南芥在高温条件下精确建立种子休眠和抑制种子萌发所必需的。
