Conserved imprinting associated with unique epigenetic signatures in the Arabidopsis genus.
Conserved imprinting associated with unique epigenetic signatures in the Arabidopsis genus.
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DOI：
10.1038/nplants.2016.145
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发表时间：
2016-09-19
期刊：
影响因子：
18
通讯作者：
Gehring M
中科院分区：
文献类型：
--
作者：
Klosinska M;Picard CL;Gehring M
在植物中，印迹基因表达发生在胚乳种子组织中，有时与母本和父本等位基因之间的差异DNA甲基化有关。印记理论上是由于后代中亲本基因组之间的冲突而被选择的，但大多数印记研究都是在拟南芥中进行的，拟南芥是一种近交的主要自交物种，应该有有限的亲本冲突。我们研究了野生异交种琴叶拟南芥的胚和胚乳等位基因特异性表达和全基因组DNA甲基化。在这里，我们证明了大多数A。琴琴印迹基因在A. thaliana，这表明在基因印迹中存在进化保守性。令人惊讶的是，我们发现了与父系表达的印迹基因（PEG）相关的甲基化特征的实质性物种间差异。与A. thaliana，许多A. lyrata PEG在CHG背景下被高甲基化。母亲等位基因CHG甲基化增加与有利于父亲等位基因的表达偏倚增加相关。我们认为CHG甲基化维持或加强了PEG的母体等位基因的抑制。这些数据表明，虽然受印记的基因在很大程度上是保守的，但在密切相关的物种之间采用的表观遗传机制中存在灵活性，以维持单等位基因表达。这支持了特定基因的印记是一种功能现象的观点，而不仅仅是种子表观基因组重编程的副产品。
In plants, imprinted gene expression occurs in endosperm seed tissue and is sometimes associated with differential DNA methylation between maternal and paternal alleles. Imprinting is theorized to have been selected for because of conflict between parental genomes in offspring, but most studies of imprinting have been conducted in Arabidopsis thaliana, an inbred primarily self-fertilizing species that should have limited parental conflict. We examined embryo and endosperm allele-specific expression and DNA methylation genome-wide in the wild outcrossing species Arabidopsis lyrata. Here we show that the majority of A. lyrata imprinted genes also exhibit parentally-biased expression in A. thaliana, suggesting that there is evolutionary conservation in gene imprinting. Surprisingly, we discovered substantial interspecies differences in methylation features associated with paternally expressed imprinted genes (PEGs). Unlike in A. thaliana, the maternal allele of many A. lyrata PEGs was hypermethylated in the CHG context. Increased maternal allele CHG methylation was associated with increased expression bias in favor of the paternal allele. We propose that CHG methylation maintains or reinforces repression of maternal alleles of PEGs. These data suggest that while the genes subject to imprinting are largely conserved, there is flexibility in the epigenetic mechanisms employed between closely related species to maintain monoallelic expression. This supports the idea that imprinting of specific genes is a functional phenomenon, and not simply a byproduct of seed epigenomic reprogramming.