• 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.

中文翻译：

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AL6 的 SUMOylation 调节拟南芥的种子休眠和热抑制

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  DELAY OF GERMINATION1 （DOG1） 是种子休眠和种子热抑制的关键调节因子。然而，DOG1 表达如何受翻译后修饰的调节以及种子如何将高温信号传递到 DOG1 在很大程度上仍然未知。
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  先前发现 ALFIN1 样 6/7 （AL6/7） 在种子吸收过程中抑制 DOG1 表达。在这里，我们发现 AL6/7 部分通过下调 DOG1 表达来抑制种子休眠。AtSIZ1 是一种 SUMO E3 连接酶，与 AL6 相互作用，主要在赖氨酸 181 残基处介导其 SUMOylation。SIZ1 介导的 AL6 SUMOylation 是抑制 DOG1 转录和种子休眠所必需的。AL6 的 SUMOylation 是其与 DOG1 基因座结合所必需的，并保护其免受泛素化和随后的 26S 蛋白酶体介导的蛋白质降解。
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  高温会降低 AL6 的 SUMOylation 水平，导致 AL6 蛋白水平下调和 DOG1 转录增加，从而导致种子发芽减少。
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  综上所述，这些结果表明，AL6 的可逆 SUMOylation 微调了 DOG1 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发芽所必需的。