Flowering time (heading date) is a critical agronomic trait that determines the yield and regional adaptability of crops. Heading date 1 (Hd1) is a central regulator of photoperiodic flowering in rice (Oryza sativa). However, how the homeostasis of Hd1 protein is achieved is poorly understood. Here, we report that the nuclear autophagy pathway mediates Hd1 degradation in the dark to regulate flowering. Loss of autophagy function results in an accumulation of Hd1 and delays flowering under both short-day and long-day conditions. In the dark, nucleus-localized Hd1 is recognized as a substrate for autophagy and is subjected to vacuolar degradation via the autophagy protein OsATG8. The Hd1-OsATG8 interaction is required for autophagic degradation of Hd1 in the dark. Our study reveals a new mechanism by which Hd1 protein homeostasis is regulated by autophagy to control rice flowering. Our study also indicates that the regulation of flowering by autophagic degradation of Hd1 orthologs may have arisen over the course of mesangiosperm evolution, which would have increased their flexibility and adaptability to the environment by modulating flowering time.

开花期（抽穗期）是决定作物产量和区域适应性的关键农艺性状。抽穗期 1 (Hd1) 是水稻光周期开花的中心调节因子 ( Oryza sativa）。然而，人们对如何实现 Hd1 蛋白的稳态知之甚少。在这里，我们报告说，核自噬途径在黑暗中介导 Hd1 降解以调节开花。自噬功能的丧失导致 Hd1 的积累，并在短日照和长日照条件下延迟开花。在黑暗中，核定位的 Hd1 被认为是自噬的底物，并通过自噬蛋白 OsATG8 进行液泡降解。Hd1-OsATG8 相互作用是在黑暗中自噬降解 Hd1 所必需的。我们的研究揭示了一种新的机制，通过这种机制，自噬调节 Hd1 蛋白稳态以控制水稻开花。我们的研究还表明，通过 Hd1 直系同源物的自噬降解对开花的调节可能在中被植物进化过程中出现，