Heading date (or flowering time) is one of the most important agronomic traits in rice, influencing its regional adaptability and crop yield. Many major-effect genes for rice heading date have been identified, but in practice they are difficult to be used for rice molecular breeding because of their dramatic effects on heading date. Genes with minor effects on heading date, which are more desirable for fine-tuning flowering time without significant yield penalty, were seldom reported. In this study, we identified a new minor-effect heading date repressor, Delayed Heading Date 4 (DHD4). The dhd4 mutant shows a slightly earlier flowering phenotype without a notable yield penalty compared with wild-type plants under natural long-day conditions. DHD4 encodes a CONSTANS-like transcription factor localized in the nucleus. Molecular, biochemical, and genetic assays show that DHD4 can compete with 14-3-3 to interact with OsFD1, thus affecting the formation of the Hd3a-14-3-3-OsFD1 tri-protein FAC complex, resulting in reduced expression of OsMADS14 and OsMADS15, and ultimately delaying flowering. Taken together, these results shed new light on the regulation of flowering time in rice and provide a promising target for fine-tuning flowering time to improve the regional adaptability of rice.

抽穗期（或开花时间）是水稻最重要的农艺性状之一，影响其区域适应性和作物产量。已经确定了许多水稻抽穗期的主要影响基因，但实际上，由于它们对抽穗期的巨大影响，它们很难用于水稻分子育种。很少报道对抽穗期有较小影响的基因，这些基因对于微调开花时间而不产生明显的产量损失更为理想。在这项研究中，我们确定了一个新的次要航向日期抑制器，延迟航向日期4（DHD4）。该dhd4突变体显示没有明显的产量点球稍早开花表型与自然长日照条件下，野生型植株相比。DHD4编码CONSTANS样转录因子位于细胞核中。分子，生化和遗传检测表明DHD4可以与14-3-3竞争与OsFD1相互作用，从而影响Hd3a-14-3-3-OsFD1三蛋白FAC复合物的形成，导致OsMADS14的表达降低和OsMADS15，最终延迟开花。综上所述，这些结果为水稻开花时间的调控提供了新的思路，并为微调开花时间以提高水稻的区域适应性提供了有希望的目标。