Summary Transcription factors of the CYCLING DOF FACTOR (CDF) family activate in potato the SP6A FT tuberization signal in leaves. In modern cultivars, truncated StCDF1.2 alleles override strict SD control by stabilizing the StCDF1 protein, which leads to StCOL1 suppression and impaired activation of the antagonic SP5G paralog. By using DAP‐seq and RNA‐seq studies, we here show that StCDF1 not only acts as an upstream regulator of the day length pathway but also directly regulates several N assimilation and transport genes. StCDF1 directly represses expression of NITRATE REDUCTASE (NR/NIA), which catalyses the first reduction step in nitrate assimilation, and is encoded by a single potato locus. StCDF1 knock‐down lines performed better in N‐limiting conditions, and this phenotype correlated with derepressed StNR expression. Also, deletion of the StNR DAP‐seq region abolished repression by StCDF1, while it did not affect NLP7‐dependent activation of the StNR promoter. We identified multiple nucleotide polymorphisms in the DAP‐seq region in potato cultivars with early StCDF1 alleles, suggesting that this genetic variation was selected as compensatory mechanism to the negative impact of StCDF1 stabilization. Thereby, directed modification of the StCDF1‐recognition elements emerges as a promising strategy to enhance limiting StNR activity in potato.

中文翻译：

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StCDF1：“万事通”时钟输出，在调节马铃薯硝酸盐还原活性中起着核心作用


摘要： 循环多夫因子 （CDF） 家族的转录因子在马铃薯中激活了叶片中的 SP6A FT 块茎化信号。在现代品种中，截短的 StCDF1.2 等位基因通过稳定 StCDF1 蛋白来覆盖严格的 SD 控制，从而导致 StCOL1 抑制和拮抗 SP5G 旁系同源物的激活受损。通过使用 DAP-seq 和 RNA-seq 研究，我们在这里表明 StCDF1 不仅作为日长通路的上游调节因子，而且还直接调节多个 N 同化和转运基因。StCDF1 直接抑制硝酸还原酶 （NR/NIA） 的表达，该酶催化硝酸盐同化的第一步还原步骤，由单个马铃薯基因座编码。StCDF1 敲低系在 N 限制条件下表现更好，并且这种表型与去抑制的 StNR 表达相关。此外，StNR DAP-seq 区域的缺失消除了 StCDF1 的抑制，而它不会影响 StNR 启动子的 NLP7 依赖性激活。我们在具有早期 StCDF1 等位基因的马铃薯品种的 DAP-seq 区域鉴定了多个核苷酸多态性，表明这种遗传变异被选为 StCDF1 稳定负面影响的补偿机制。因此，StCDF1 识别元件的定向修饰成为增强马铃薯中限制 StNR 活性的一种有前途的策略。