Bypassing genomic imprinting allows seed development
Bypassing genomic imprinting allows seed development
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DOI：
10.1038/nature05770
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发表时间：
2007-05-17
期刊：
影响因子：
64.8
通讯作者：
Schnittger, Arp
中科院分区：
文献类型：
--
作者：
Nowack, Moritz K.;Shirzadi, Reza;Schnittger, Arp
在哺乳动物的发育后代中，根据印迹标记，两个亲本基因组的表达是不同的，只有一个亲本基因贡献的胚胎死亡（1-3）。在开花植物的后代中也观察到依赖原生亲本的基因表达，印迹机制的突变导致胚胎致死，主要影响胚乳的发育——胚乳是种子中滋养胚胎的结构，类似于哺乳动物胎盘的功能(4)。在这里，我们已经产生了拟南芥种子，其中胚乳是单亲的，也就是说，母系起源。我们证明了在发育中的种子可以绕过和可行的印迹，尽管较小的幼苗可以从缺乏父本对胚乳贡献的种子发育出来。只有当母亲是任何fis类基因的突变体时才有可能绕过，fis类基因编码Polycomb组染色质修饰因子。因此，这些数据提供了功能性证据，证明FIS复合体的作用平衡了父系基因组的贡献。由于开花植物进化出了一种特殊的生殖系统，即两个雌性配子和两个雄性配子平行融合，我们的研究结果支持了双受精进化过程中FIS基因的作用成为种子发育的必要条件的假设。此外，我们的数据支持开花植物胚乳的配子体起源，从而支持edward Strasburger在1900年提出的假设。
In developing progeny of mammals the two parental genomes are differentially expressed according to imprinting marks, and embryos with only a uniparental genetic contribution die(1-3). Gene expression that is dependent on the parent of origin has also been observed in the offspring of flowering plants, and mutations in the imprinting machinery lead to embryonic lethality, primarily affecting the development of the endosperm - a structure in the seed that nourishes the embryo, analogous to the function of the mammalian placenta(4). Here we have generated Arabidopsis thaliana seeds in which the endosperm is of uniparental, that is, maternal, origin. We demonstrate that imprinting in developing seeds can be bypassed and viable albeit smaller seedlings can develop from seeds lacking a paternal contribution to the endosperm. Bypassing is only possible if the mother is mutant for any of the FIS-class genes, which encode Polycomb group chromatin-modifying factors. Thus, these data provide functional evidence that the action of the FIS complex balances the contribution of the paternal genome. As flowering plants have evolved a special reproduction system with a parallel fusion of two female with two male gametes, our findings support the hypothesis that only with the evolution of double fertilization did the action of the FIS genes become a requirement for seed development. Furthermore, our data argue for a gametophytic origin of endosperm in flowering plants, thereby supporting a hypothesis raised in 1900 by Eduard Strasburger.