The phase transition from vegetative to reproductive growth is triggered by internal and external signals that participate in circadian clock in plants. We identified a rice floral inhibitor OsPRR73 encoding a CONSTANS protein. Overexpression of OsPRR73 resulted in late heading under both long‐day (LD) and short‐day (SD) conditions. Knockout mutants led to early heading under LD conditions but no change under SD. OsPRR73 mRNA accumulated at noon and exhibited a robust oscillation under constant light (LL) and constant darkness (DD) conditions. OsPRR73 overexpression exerted negative feedback on endogenous OsPRR73 expression and altered diurnal expressions of key flowering genes and circadian clock genes. OsPRR73 bound to the promoters of the floral gene Ehd1 and the circadian gene OsLHY, and significantly suppressed their expression at dawn. In LL and DD, the oscillatory patterns of the circadian genes OsLHY, OsTOC1, OsGI and OsELF3 were varied in OsPRR73OX and osprr73 mutants. OsPRR73 expression was decreased in osphyb mutants, and overexpression of OsPRR73 complemented the early heading date phenotype of osphyb, indicating OsPRR73 works downstream of OsPhyB. Therefore, OsPRR73 is involved in a feedback loop of the rice clock and connects the photoperiod flowering pathway by binding to the Ehd1 promoter in rice.

中文翻译：

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转录阻抑物OsPRR73连接昼夜节律和光周期途径来控制水稻的抽穗期

从营养生长到生殖生长的相变是由参与植物生物钟的内部和外部信号触发的。我们鉴定了编码CONSTANS蛋白的水稻花卉抑制剂OsPRR73。OsPRR73的过表达导致在长日（LD）和短日（SD）条件下的航向晚。敲除突变体导致LD条件下的早期抽穗，但SD条件下无变化。OsPRR73 mRNA在中午积累，并在恒定光照（LL）和恒定黑暗（DD）条件下表现出强大的振荡。OsPRR73过表达对内源性OsPRR73产生负反馈开花基因和昼夜节律基因的表达和昼夜表达变化。OsPRR73绑定到花卉基因Ehd1和昼夜节律基因OsLHY的启动子，并显着抑制它们在黎明时的表达。在LL和DD中，昼夜节律基因OsLHY，OsTOC1，OsGI和OsELF3的振荡模式在OsPRR73OX和osprr73突变体中有所不同。OsPRR73表达下降osphyb突变体和过表达OsPRR73补充的早期抽穗期表型osphyb，指示OsPRR73在OsPhyB的下游工作。因此，OsPRR73参与水稻时钟的反馈回路，并通过与水稻中的Ehd1启动子结合而连接光周期开花途径。