The induction of C‐repeat binding factors (CBFs) is crucial for plant survival at low temperatures. Therefore, understanding the mechanisms that regulate CBF transcription is vital for the future development of crops with increased cold tolerance. Here, we provide evidence for the existence of a LONG HYPOCOTYL 5 (HY5)‐MYB15‐CBFs transcriptional cascade that plays a crucial role in the cold response in tomato. The exposure of tomato plants to cold (4°C) increased the levels of HY5, MYB15 and CBFs transcripts. Moreover, mutations in HY5 or MYB15 decreased the levels of CBF transcripts. In contrast, overexpression of HY5 or MYB15 increased CBF transcript abundance. Crucially, the HY5 transcription factor activated the expression of MYB15 by directly binding to the promoter region, while both HY5 and MYB15 activated the expression of CBF1, CBF2 and CBF3. Taken together, these data show that HY5 can directly regulate CBF transcript levels, and also influence CBF expression indirectly via MYB15. The coordinated action of HY5 and MYB15 allows precise regulation of CBF expression and subsequent cold tolerance. These findings provide an improved understanding of the molecular mechanisms affording transcriptional regulation of CBFs, which can be exploited in the future to enhance cold tolerance in crops.

中文翻译：

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HY5和MYB15转录因子通过CBF途径正调控番茄的耐寒性。

C-重复结合因子（CBF）的诱导对于低温下植物的存活至关重要。因此，了解调节CBF转录的机制对于提高耐寒性的作物的未来发展至关重要。在这里，我们提供了证据表明存在长的hypocotyyl 5（HY5）‐MYB15‐CBFs转录级联反应，该转录级联反应在番茄的冷反应中起着至关重要的作用。番茄植物暴露于冷（4°C）下会增加HY5，MYB15和CBFs转录本的水平。此外，HY5或MYB15中的突变降低了CBF转录本的水平。相反，HY5或MYB15增加了CBF转录本的丰度。至关重要的是，HY5转录因子活化的表达MYB15通过直接结合到启动子区，而HY5和MYB15两个激活的表达CBF1，CBF2和CBF3。总之，这些数据表明HY5可以直接调节CBF转录水平，也可以通过MYB15间接影响CBF表达。HY5和MYB15的协同作用可精确调节CBF表达和随后的耐寒性。这些发现提供了对提供CBFs转录调控的分子机制的更好理解，可在将来被利用来增强作物的耐寒性。