Key Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes, Institute of Plant and Food Science, Department of Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen 518055, China.
National Key Laboratory for Crop Genetics and Germplasm Enhancement, Bioinformatics Center, Jiangsu Collaborative Innovation Center for Modern Crop Production, Nanjing Agricultural University, Nanjing 210095, China.
Plant Cell. 2022 Jul 30;34(8):2871-2891. doi: 10.1093/plcell/koac134.
Seed germination represents a major developmental switch in plants that is vital to agriculture, but how this process is controlled at the chromatin level remains obscure. Here we demonstrate that successful germination in Arabidopsis thaliana requires a chromatin mechanism that progressively silences 9-CIS-EPOXYCAROTENOID DIOXYGENASE 6 (NCED6), which encodes a rate-limiting enzyme in abscisic acid (ABA) biosynthesis, through the cooperative action of the RNA-binding protein RZ-1 and the polycomb repressive complex 2 (PRC2). Simultaneous inactivation of RZ-1 and PRC2 blocked germination and synergistically derepressed NCEDs and hundreds of genes. At NCED6, in part by promoting H3 deacetylation and suppressing H3K4me3, RZ-1 facilitates transcriptional silencing and also an H3K27me3 accumulation process that occurs during seed germination and early seedling growth. Genome-wide analysis revealed that RZ-1 is preferentially required for transcriptional silencing of many PRC2 targets early during seed germination, when H3K27me3 is not yet established. We propose RZ-1 confers a novel silencing mechanism to compensate for and synergize with PRC2. Our work highlights the progressive chromatin silencing of ABA biosynthesis genes via the RNA-binding protein RZ-1 and PRC2 acting in synergy, a process that is vital for seed germination.
种子萌发代表着植物发育的一个主要转变，对农业至关重要，但这个过程如何在染色质水平上被控制仍然不清楚。在这里，我们证明了拟南芥成功萌发需要一个染色质机制，通过 RNA 结合蛋白 RZ-1 和多梳抑制复合物 2 (PRC2) 的协同作用，该机制逐渐沉默编码脱落酸 (ABA) 生物合成中限速酶的 9-CIS-环氧类胡萝卜素双加氧酶 6 (NCED6)。RZ-1 和 PRC2 的同时失活阻止了萌发，并协同去抑制 NCEDs 和数百个基因。在 NCED6 上，部分通过促进 H3 去乙酰化和抑制 H3K4me3，RZ-1 促进转录沉默，并在种子萌发和早期幼苗生长过程中发生 H3K27me3 积累过程。全基因组分析表明，RZ-1 优先需要在种子萌发早期许多 PRC2 靶基因的转录沉默，此时 H3K27me3 尚未建立。我们提出 RZ-1 赋予了一种新的沉默机制，以补偿和协同 PRC2。我们的工作强调了通过 RNA 结合蛋白 RZ-1 和 PRC2 的协同作用，对 ABA 生物合成基因进行渐进性染色质沉默的过程，这对种子萌发至关重要。
