Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.
University of Chinese Academy of Sciences, Beijing 100049, China.
Plant Physiol. 2021 Sep 4;187(1):289-302. doi: 10.1093/plphys/kiab147.
Seed dormancy and germination are fundamental processes for plant propagation, both of which are tightly regulated by internal and external cues. Phytochrome B (phyB) is a major red/far-red-absorbing photoreceptor that senses light signals that modulate seed dormancy and germination. However, the components that directly transduce that signal downstream of phyB are mostly unknown. Here, we show that the transposase-derived transcription factor FAR-RED ELONGATED HYPOCOTYL3 (FHY3) inhibits seed dormancy and promotes phyB-mediated seed germination in Arabidopsis thaliana. FHY3 physically interacts with phyB in vitro and in vivo. RNA-sequencing and reverse transcription-quantitative polymerase chain reaction analyses showed that FHY3 regulates multiple downstream genes, including REVEILLE2 (RVE2), RVE7, and SPATULA (SPT). Yeast one-hybrid, electrophoresis mobility shift, and chromatin immunoprecipitation assays demonstrated that FHY3 directly binds these genes via a conserved FBS cis-element in their promoters. Furthermore, RVE2, RVE7, and GIBBERELLIN 3-OXIDASE 2 (GA3ox2) genetically act downstream of FHY3. Strikingly, light and phyB promote FHY3 protein accumulation. Our study reveals a transcriptional cascade consisting of phyB-FHY3-RVE2/RVE7/SPT-GA3ox2 that relays environmental light signals and thereby controls seed dormancy and germination.
种子休眠和萌发是植物繁殖的基本过程，这两个过程都受到内部和外部线索的严格调控。光敏色素 B（phyB）是一种主要的红光/远红光吸收光受体，它能感知调节种子休眠和萌发的光信号。然而，phyB 下游直接转导该信号的成分在很大程度上尚不清楚。在这里，我们表明转座酶衍生的转录因子远红光延长下胚轴 3（FHY3）抑制种子休眠并促进拟南芥中 phyB 介导的种子萌发。FHY3 在体外和体内均与 phyB 相互作用。RNA 测序和反转录定量聚合酶链反应分析表明，FHY3 调节多个下游基因，包括 REVEILLE2（RVE2）、RVE7 和 SPATULA（SPT）。酵母单杂交、电泳迁移率变动分析和染色质免疫沉淀试验表明，FHY3 通过其启动子中保守的 FBS 顺式元件直接结合这些基因。此外，RVE2、RVE7 和赤霉素 3-氧化酶 2（GA3ox2）在 FHY3 下游遗传上起作用。引人注目的是，光和 phyB 促进 FHY3 蛋白积累。我们的研究揭示了一个由 phyB-FHY3-RVE2/RVE7/SPT-GA3ox2 组成的转录级联反应，该级联反应传递环境光信号，从而控制种子休眠和萌发。
