Pumpkin CmoNAC1 enhances salt tolerance in grafted cucumbers. However, the potential interactions with other proteins that may co-regulate salt tolerance alongside CmoNAC1 have yet to be explored. In this study, we identified pumpkin CmoDREB2A as a pivotal transcription factor that interacts synergistically with CmoNAC1 in the co-regulation of salt tolerance. Both transcription factors were observed to bind to each other's promoters, forming a positive regulatory loop of their transcription. Knockout of CmoDREB2A in the root resulted in reduced salt tolerance in grafted cucumbers, whereas overexpression demonstrated the opposite effect. Multiple assays in our study provided evidence of the protein interaction between CmoDREB2A and CmoNAC1. Exploiting this interaction, CmoDREB2A facilitated the binding of CmoNAC1 to the promoters of CmoRBOHD1, CmoNCED6, CmoAKT1;2, and CmoHKT1;1, inducing H2O2 and ABA synthesis and increasing the K+/Na+ ratio in grafted cucumbers under salt stress. Additionally, CmoNAC1 also promoted the binding of CmoDREB2A to CmoHAK5;1/CmoHAK5;2 promoters, further contributing to the K+/Na+ homeostasis. In summary, these findings reveal a crucial mechanism of CmoNAC1 and CmoDREB2A forming a complex enhancing salt tolerance in grafted cucumbers.

中文翻译：

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南瓜 CmoDREB2A 通过与 CmoNAC1 相互作用调节 H2O2 和 ABA 信号传导以及 K+/Na+ 稳态来增强嫁接黄瓜的耐盐性

南瓜 CmoNAC1 增强嫁接黄瓜的耐盐性。然而，与其他可能与 CmoNAC1 一起共同调节耐盐性的蛋白质之间的潜在相互作用仍有待探索。在这项研究中，我们发现南瓜 CmoDREB2A 是一种关键转录因子，在共同调节耐盐性方面与 CmoNAC1 协同相互作用。观察到两个转录因子都与彼此的启动子结合，形成其转录的正调节环。根部 CmoDREB2A 的敲除会导致嫁接黄瓜的耐盐性降低，而过度表达则会产生相反的效果。我们研究中的多项测定提供了 CmoDREB2A 和 CmoNAC1 之间蛋白质相互作用的证据。利用这种相互作用，CmoDREB2A 促进 CmoNAC1 与 CmoRBOHD1、CmoNCED6、CmoAKT1;2 和 CmoHKT1;1 启动子的结合，诱导 H2O2 和 ABA 合成，并增加盐胁迫下嫁接黄瓜中 K+/Na+ 的比例。此外，CmoNAC1 还促进 CmoDREB2A 与 CmoHAK5;1/CmoHAK5;2 启动子的结合，进一步促进 K+/Na+ 稳态。总之，这些发现揭示了 CmoNAC1 和 CmoDREB2A 形成复合物增强嫁接黄瓜耐盐性的关键机制。