Heritable changes of epialleles near genes in maize can be triggered in the absence of CHH methylation
Heritable changes of epialleles near genes in maize can be triggered in the absence of CHH methylation
复制标题
DOI：
10.1093/plphys/kiad668
复制
发表时间：
2023-12
期刊：
影响因子：
7.4
通讯作者：
Beibei Liu;Diya Yang;Dafang Wang;Chun Liang;Jianping Wang;D. Lisch;Meixia Zhao
中科院分区：
文献类型：
--
作者：
Beibei Liu;Diya Yang;Dafang Wang;Chun Liang;Jianping Wang;D. Lisch;Meixia Zhao
摘要跨染色体相互作用导致杂交过程中DNA甲基化的变化已在几种植物中观察到。然而，人们对这些相互作用的原因或后果知之甚少。在这里，我们比较了DNA甲基化的F1杂种的突变体的小RNA生物发生基因，Mop 1（介体paramutation1），与他们的父母，野生型兄弟姐妹，和回交后代的玉米（玉米）。我们的数据显示，杂交触发了跨染色体甲基化（TCM）和跨染色体去甲基化（TCdM）的全局变化，其中大部分涉及CHH甲基化的变化。在超过60%的这些TCM差异甲基化区域（DMR）中，小RNA是可用的，没有观察到小RNA的数量的显着变化。在CHH TCM DMR的甲基化在mop 1突变体中大部分丢失，尽管该突变体的影响根据这些DMR的位置而变化。有趣的是，TCM DMR中CHH的增加与高表达基因子集的表达增强和少量低表达基因的表达抑制相关。对回交植株甲基化水平的检测表明，TCM和TCdM都可以在后代中保持，但TCdM比TCM更稳定。令人惊讶的是，尽管F1植物中大多数TCM DMR中CHH甲基化的增加需要Mop 1，但这些DMR的新表观遗传状态的启动并不需要该基因的功能拷贝，这表明这些变化的启动独立于RNA指导的DNA甲基化。
Abstract Trans-chromosomal interactions resulting in changes in DNA methylation during hybridization have been observed in several plant species. However, little is known about the causes or consequences of these interactions. Here, we compared DNA methylomes of F1 hybrids that are mutant for a small RNA biogenesis gene, Mop1 (Mediator of paramutation1), with that of their parents, wild-type siblings, and backcrossed progeny in maize (Zea mays). Our data show that hybridization triggers global changes in both trans-chromosomal methylation (TCM) and trans-chromosomal demethylation (TCdM), most of which involved changes in CHH methylation. In more than 60% of these TCM differentially methylated regions (DMRs) in which small RNAs are available, no significant changes in the quantity of small RNAs were observed. Methylation at the CHH TCM DMRs was largely lost in the mop1 mutant, although the effects of this mutant varied depending on the location of these DMRs. Interestingly, an increase in CHH at TCM DMRs was associated with enhanced expression of a subset of highly expressed genes and suppressed expression of a small number of lowly expressed genes. Examination of the methylation levels in backcrossed plants demonstrates that both TCM and TCdM can be maintained in the subsequent generation, but that TCdM is more stable than TCM. Surprisingly, although increased CHH methylation in most TCM DMRs in F1 plants required Mop1, initiation of a new epigenetic state of these DMRs did not require a functional copy of this gene, suggesting that initiation of these changes is independent of RNA-directed DNA methylation.