海南大学Jing Li研究小组发现，两个印记基因在中心细胞中由DME启动并在胚乳中由WRKY10激活。这一研究成果于2024年4月8日在线发表在国际学术期刊《遗传学报》上。

研究人员引入了两个早期胚乳表达的ICF1和ICF2，作为母本表达的印记基因（MEG）。虽然这些基因在中心细胞中也会被DEMETER（DME）去甲基化，但它们的激活不同于FIS基因等经典MEG中DME介导的直接激活。相反，ICF母本等位基因的启动子中预先形成了低甲基化，使它们在胚乳中被WRKY10转录因子激活。相反，父本等位基因主要受到CG甲基化的抑制。

此外，研究人员还证明，ICF基因在一定程度上导致了iku突变体种子体积小。这些发现揭示了一种两步调控机制，突出了常规转录因子在激活印记基因中的重要作用，而这一作用以前并未得到充分认识。因此，该机制为理解植物繁殖和发育中印记的转录调控提供了一个新的维度。

研究人员表示，胚乳的早期发育对于平衡母体营养物质对后代的分配至关重要。这一过程在演化过程中被认为与基因组印记有关，从而导致亲本偏向等位基因的表达。除了FIS（Fertilization Independent Seed）基因外，参与早期胚乳发育和种子大小决定的印记基因数量仍然有限。

附：英文原文

Title: Two imprinted genes primed by DME in the central cell and activated by WRKY10 in the endosperm

Author: Jing Li b c d

Issue&Volume: 2024/04/08

Abstract: The early development of the endosperm is crucial for balancing the allocation of maternal nutrients to offspring. This process is believed to be evolutionarily associated with genomic imprinting, resulting in parentally biased allelic gene expression. Beyond FIS (Fertilization Independent Seed) genes, the number of imprinted genes involved in early endosperm development and seed size determination remains limited. This study introduces two early endosperm-expressed ICF1 and ICF2, as maternally expressed imprinted genes (MEGs). Although these genes are also demethylated by DEMETER (DME) in the central cell, their activation differs from the direct DME-mediated activation seen in classical MEGs such as the FIS genes. Instead, ICF maternal alleles carry pre-established hypomethylation in their promoters, priming them for activation by the WRKY10 transcription factor in the endosperm. On the contrary, paternal alleles are predominantly suppressed by CG methylation. Furthermore, we demonstrated that ICF genes partially contribute to the small seed size observed in iku mutants. Our discovery reveals a two-step regulatory mechanism that highlights the important role of conventional transcription factors in the activation of imprinted genes, which was previously not fully recognized. Therefore, the mechanism provides a new dimension to understanding the transcriptional regulation of imprinting in plant reproduction and development.

DOI: 10.1016/j.jgg.2024.04.003

Source: https://www.sciencedirect.com/science/article/abs/pii/S1673852724000729