Table_1_Arabidopsis Histone Methyltransferase SUVH5 Is a Positive Regulator of Light-Mediated Seed Germination.XLSX

Plant lifecycle starts from seed germination, which is regulated by various environmental cues and endogenous hormones. Light promotes seed germination mainly by phytochrome B (PHYB) during the initial phase of imbibition, which involves genome-wide light-responsive transcription changes. Recent studies indicated an involvement of multiple epigenetic factors in the control of seed germination. However, few studies have been reported about the role of a histone methyltransferase in light-mediated seed germination process. Here, we identified SUVH5, a histone H3 lysine 9 methyltransferase, as a positive regulator in light-mediated seed germination in Arabidopsis. Loss of function of SUVH5 leads to decreased PHYB-dependent seed germination. RNA-sequencing analysis displayed that SUVH5 regulates 24.6% of light-responsive transcriptome in imbibed seeds, which mainly related to hormonal signaling pathways and developmental processes. Furthermore, SUVH5 represses the transcription of ABA biosynthesis and signal transduction-related genes, as well as a family of DELAY OF GERMINATION (DOG) genes via dimethylation of histone H3 at lysine 9 (H3K9me2) in imbibed seeds. Taken together, our findings revealed that SUVH5 is a novel positive regulator of light-mediated seed germination in Arabidopsis.

植物生命周期始于种子萌发，该过程受多种环境信号与内源激素共同调控。在吸胀初始阶段，光主要通过光敏色素B（phytochrome B, PHYB）促进种子萌发，此过程涉及全基因组范围的光响应转录调控变化。已有研究表明，多种表观遗传因子参与调控种子萌发过程。然而，目前鲜有关于组蛋白甲基转移酶在光介导种子萌发过程中作用的相关报道。本研究鉴定出SUVH5——一种组蛋白H3赖氨酸9甲基转移酶——作为拟南芥光介导种子萌发的正向调控因子。SUVH5功能缺失会导致依赖PHYB的种子萌发率降低。RNA测序分析显示，SUVH5调控吸胀种子中24.6%的光响应转录组，其靶标基因主要参与激素信号通路与发育过程。进一步研究发现，SUVH5可通过在吸胀种子中对组蛋白H3赖氨酸9进行二甲基化修饰（H3K9me2），抑制脱落酸（ABA）生物合成与信号转导相关基因，以及种子萌发延迟（DELAY OF GERMINATION, DOG）基因家族的转录。综上，本研究结果表明SUVH5是拟南芥光介导种子萌发的新型正向调控因子。