Transcriptional repression specifies the central cell for double fertilization
Transcriptional repression specifies the central cell for double fertilization
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DOI：
10.1073/pnas.1909465117
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发表时间：
2020-03
期刊：
影响因子：
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通讯作者：
Meng-Xia Zhang;Shanshan Zhu;Yong-Chao Xu;Ya-long Guo;Wei-cai Yang;Hong-Ju Li
中科院分区：
文献类型：
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作者：
Meng-Xia Zhang;Shanshan Zhu;Yong-Chao Xu;Ya-long Guo;Wei-cai Yang;Hong-Ju Li
意义双受精是显花植物的一项重要创新。中央细胞是第二个雌配子，它的受精作用产生胚乳，胚乳是种子的养育者。然而，这种细胞如何在被子植物中被指定和进化仍然未知。本研究揭示了一种转录抑制机制，以指定在拟南芥的中央细胞，并提供了深入了解这种机制在拟南芥科的起源。双受精是被子植物进化成功的关键创新，通过双受精，两个受精的雌配子，卵细胞和中央细胞，分别产生胚胎和胚乳。孢子体中的雌配子体（胚囊）来自单细胞的单倍体细胞谱系。它经历了连续的有丝分裂、细胞化和细胞特化的事件，以产生成熟的胚囊，胚囊包含两个雌性配子，伴随着两种类型的辅助细胞，即助细胞和反足细胞。中央细胞的细胞命运如何被指定长期以来一直是模棱两可的，并进一步复杂化的结构多样性的雌配子体在植物类群。在这里，MADS盒蛋白AGL 80被证实为直接抑制辅助细胞特异性基因的表达以指定中央细胞的转录阻遏物。进一步的遗传拯救和系统发育分析的AGL80直向同源物揭示了一个可能的保守机制，在菊科。本研究的结果为进一步探讨菊科植物第二雌配子细胞的分子决定机制提供了理论依据。
Significance Double fertilization is a key innovation of flowering plants. The central cell is the second female gamete, and its fertilization gives rise to the endosperm, the nurse of a seed. However, how this cell is specified and evolved in angiosperm remains unknown. This study reveals a transcriptional repression mechanism to specify the central cell in Arabidopsis and provides insight into the origination of this mechanism in Brassicaceae. Double fertilization is a key innovation for the evolutionary success of angiosperms by which the two fertilized female gametes, the egg cell and central cell, generate the embryo and endosperm, respectively. The female gametophyte (embryo sac) enclosed in the sporophyte is derived from a one-celled haploid cell lineage. It undergoes successive events of mitotic divisions, cellularization, and cell specification to give rise to the mature embryo sac, which contains the two female gametes accompanied by two types of accessory cells, namely synergids and antipodals. How the cell fate of the central cell is specified has long been equivocal and is further complicated by the structural diversity of female gametophyte across plant taxa. Here, MADS-box protein AGL80 was verified as a transcriptional repressor that directly suppresses the expression of accessory cell-specific genes to specify the central cell. Further genetic rescue and phylogenetic assay of the AGL80 orthologs revealed a possible conserved mechanism in the Brassicaceae family. Results from this study provide insight into the molecular determination of the second female gamete cell in Brassicaceae.