CAS Center for Excellence in Molecular Plant Sciences, School of Life Sciences, University of Science & Technology of China, Hefei, Anhui, 230027, China.
School of Life Sciences, Anhui Agricultural University, Hefei, Anhui, 230036, China.
New Phytol. 2018 Jul;219(1):422-435. doi: 10.1111/nph.15122. Epub 2018 Apr 3.
Flowering time (heading date) in rice (Oryza sativa) is an important agronomic trait that determines yield. The levels of histone H3 lysine 4 trimethylation (H3K4me3) modulated by TRITHORAX-like proteins regulate gene transcription, flowering time and environmental stress responses. However, plant TRITHORAX-like proteins have no known DNA-binding domain, and therefore the mechanism that gives sequence specificity to these proteins remains unclear. Here, we show that the rice TRITHORAX-like protein OsTrx1 is recruited to its target, Early heading date 1 (Ehd1), by the C2H2 zinc finger protein SDG723/OsTrx1/OsSET33 Interaction Protein 1 (SIP1). SIP1 binds to the promoter of Ehd1 and interacts with OsTrx1. Mutations in SIP1 led to a late heading date under long-day and short-day conditions. Defects in OsTrx1 or SIP1 led to reduced H3K4me3 levels at Ehd1, thus reducing Ehd1 expression. Together, our results show that the transcription factor SIP1 interacts with OxTrx1, allowing OsTrx1 to specifically target Ehd1, altering H3K4me3 levels, increasing Ehd1 expression and thereby promoting flowering.
开花时间（抽穗期）是决定水稻（Oryza sativa）产量的一个重要农艺性状。三突花矩相关蛋白（TRITHORAX-like proteins）调节的组蛋白 H3 赖氨酸 4 三甲基化（H3K4me3）水平调控基因转录、开花时间和环境胁迫响应。然而，植物 TRITHORAX-like 蛋白没有已知的 DNA 结合域，因此这些蛋白赋予序列特异性的机制尚不清楚。在这里，我们表明，水稻 TRITHORAX-like 蛋白 OsTrx1 被 C2H2 锌指蛋白 SDG723/OsTrx1/OsSET33 互作蛋白 1（SIP1）募集到其靶基因 Early heading date 1（Ehd1）。SIP1 结合到 Ehd1 的启动子上并与 OsTrx1 相互作用。SIP1 突变导致长日和短日条件下抽穗期延迟。OsTrx1 或 SIP1 的缺陷导致 Ehd1 处的 H3K4me3 水平降低，从而降低 Ehd1 的表达。总之，我们的结果表明，转录因子 SIP1 与 OxTrx1 相互作用，允许 OsTrx1 特异性地靶向 Ehd1，改变 H3K4me3 水平，增加 Ehd1 的表达，从而促进开花。
