The DTH8-Hd1 Module Mediates Day-Length-Dependent Regulation of Rice Flowering
The DTH8-Hd1 Module Mediates Day-Length-Dependent Regulation of Rice Flowering
复制标题
DTH8-Hd1 模块介导水稻开花的日长依赖性调节。
DOI：
10.1016/j.molp.2017.05.006
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发表时间：
2017-07-05
期刊：
影响因子：
27.5
通讯作者：
Ouyang, Xinhao
中科院分区：
文献类型：
--
作者：
Du, Anping;Tian, Wei;Ouyang, Xinhao
光周期开花是控制水稻开花的重要途径之一，其中抽穗期1（Heading date 1，Hd 1）是拟南芥CONSTANS基因的直系同源基因，编码一个重要的光周期开花调控因子。Hd 1通过调节水稻中的抽穗期3a（Heading date 3a，Hd 3a）（FLOWERDLOCUS T（FT）直系同源基因）的表达，在短日照条件下促进开花，而在长日照条件下抑制开花。然而，Hd 1如何改变其调节活性的分子机制在很大程度上仍然是未知的。在这项研究中，我们证明，抑制开花LD由Hd 1是依赖于转录因子天标题8（DTH 8）。DTH 8功能的丧失导致Hd 3a被Hd 1激活，导致早期开花。我们发现，Hd 1直接与DTH 8相互作用，DTH 8-Hd 1复合物的形成是必要的Hd 1在LD中的Hd 3a的转录抑制，这意味着在LD中，而不是在SD中，由DTH 8介导的Hd 1功能的开关。此外，我们发现DTH 8与Hd 3a启动子相关，以调节Hd 3a基因座处的H3 K27三甲基化（H3 K27 me 3）水平。在DTH 8-Hd 1复合物的存在下，H3 K27 me 3水平在Hd 3a处增加，而DTH 8功能的丧失导致H3 K27 me 3水平在Hd 3a处降低。综上所述，我们的研究结果表明，在响应日长，DTH 8在介导Hd 3a的转录调控Hd 1通过DTH 8-Hd 1模块塑造表观遗传修饰在光周期开花中起着至关重要的作用。
Photoperiodic flowering is one of the most important pathways to govern flowering in rice (Oryza sativa), in which Heading date 1 (Hd1), an ortholog of the Arabidopsis CONSTANS gene, encodes a pivotal regulator. Hd1 promotes flowering under short-day conditions (SD) but represses flowering under long-day conditions (LD) by regulating the expression of Heading date 3a (Hd3a), the FLOWERING LOCUS T (FT) ortholog in rice. However, the molecular mechanism of how Hd1 changes its regulatory activity in response to day length remains largely unknown. In this study, we demonstrated that the repression of flowering in LD by Hd1 is dependent on the transcription factor DAYS TO HEADING 8 (DTH8). Loss of DTH8 function results in the activation of Hd3a by Hd1, leading to early flowering. We found that Hd1 directly interacts with DTH8 and that the formation of the DTH8-Hd1 complex is necessary for the transcriptional repression of Hd3a by Hd1 in LD, implicating that the switch of Hd1 function is mediated by DTH8 in LD rather than in SD. Furthermore, we revealed that DTH8 associates with the Hd3a promoter to modulate the level of H3K27 trimethylation (H3K27me3) at the Hd3a locus. In the presence of the DTH8-Hd1 complex, the H3K27me3 level was increased at Hd3a, whereas loss of DTH8 function resulted in decreased H3K27me3 level at Hd3a. Taken together, our findings indicate that, in response to day length, DTH8 plays a critical role in mediating the transcriptional regulation of Hd3a by Hd1 through the DTH8-Hd1 module to shape epigenetic modifications in photoperiodic flowering.