Gu Dachuan, Chen Chia-Yang, Zhao Minglei, Zhao Linmao, Duan Xuewu, Duan Jun, Wu Keqiang, Liu Xuncheng
Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China.
University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100049, China.
Nucleic Acids Res. 2017 Jul 7;45(12):7137-7150. doi: 10.1093/nar/gkx283.
Light is a major external factor in regulating seed germination. Photoreceptor phytochrome B (PHYB) plays a predominant role in promoting seed germination in the initial phase after imbibition, partially by repressing phytochrome-interacting factor1 (PIF1). However, the mechanism underlying the PHYB-PIF1-mediated transcription regulation remains largely unclear. Here, we identified that histone deacetylase15 (HDA15) is a negative component of PHYB-dependent seed germination. Overexpression of HDA15 in Arabidopsis inhibits PHYB-dependent seed germination, whereas loss of function of HDA15 increases PHYB-dependent seed germination. Genetic evidence indicated that HDA15 acts downstream of PHYB and represses seed germination dependent on PIF1. Furthermore, HDA15 interacts with PIF1 both in vitro and in vivo. Genome-wide transcriptome analysis revealed that HDA15 and PIF1 co-regulate the transcription of the light-responsive genes involved in multiple hormonal signaling pathways and cellular processes in germinating seeds in the dark. In addition, PIF1 recruits HDA15 to the promoter regions of target genes and represses their expression by decreasing the histone H3 acetylation levels in the dark. Taken together, our analysis uncovered the role of histone deacetylation in the light-regulated seed germination process and identified that HDA15-PIF1 acts as a key repression module directing the transcription network of seed germination.
光是调节种子萌发的主要外部因素。光受体phytochrome B（PHYB）在吸胀后的初始阶段促进种子萌发中起主要作用，部分原因是通过抑制phytochrome相互作用因子1（PIF1）。然而，PHYB-PIF1介导的转录调控的潜在机制仍不清楚。在这里，我们发现组蛋白去乙酰化酶15（HDA15）是PHYB依赖的种子萌发的负调控成分。在拟南芥中过表达HDA15会抑制PHYB依赖的种子萌发，而HDA15功能缺失则会增加PHYB依赖的种子萌发。遗传证据表明，HDA15在PHYB下游起作用，并抑制依赖PIF1的种子萌发。此外，HDA15在体外和体内均与PIF1相互作用。全基因组转录组分析表明，HDA15和PIF1共同调控参与黑暗中萌发种子多种激素信号通路和细胞过程的光响应基因的转录。此外，PIF1在黑暗中招募HDA15到靶基因的启动子区域，并通过降低组蛋白H3乙酰化水平来抑制它们的表达。综上所述，我们的分析揭示了组蛋白去乙酰化在光调节种子萌发过程中的作用，并确定HDA15-PIF1作为一个关键的抑制模块指导种子萌发的转录网络。
