University Program in Ecology Duke University, Durham, NC 27705, USA.
Center for Agricultural Synthetic Biology, University of Tennessee, Knoxville, TN 37996, USA.
Ann Bot. 2022 Dec 16;130(6):883-899. doi: 10.1093/aob/mcac125.
Environments experienced by both parents and offspring influence progeny traits, but the epigenetic mechanisms that regulate the balance of parental vs. progeny control of progeny phenotypes are not known. We tested whether DNA methylation in parents and/or progeny mediates responses to environmental cues experienced in both generations.
Using Arabidopsis thaliana, we manipulated parental and progeny DNA methylation both chemically, via 5-azacytidine, and genetically, via mutants of methyltransferase genes, then measured progeny germination responses to simulated canopy shade in parental and progeny generations.
We first found that germination of offspring responded to parental but not seed demethylation. We further found that parental demethylation reversed the parental effect of canopy in seeds with low (Cvi-1) to intermediate (Col) dormancy, but it obliterated the parental effect in seeds with high dormancy (Cvi-0). Demethylation did so by either suppressing germination of seeds matured under white-light (Cvi-1) or under canopy (Cvi-0), or by increasing the germination of seeds matured under canopy (Col). Disruption of parental methylation also prevented seeds from responding to their own light environment in one genotype (Cvi-0, most dormant), but it enabled seeds to respond to their own environment in another genotype (Cvi-1, least dormant). Using mutant genotypes, we found that both CG and non-CG DNA methylation were involved in parental effects on seed germination.
Parental methylation state influences seed germination more strongly than does the progeny's own methylation state, and it influences how seeds respond to environments of parents and progeny in a genotype-specific manner.
父母和后代所经历的环境会影响后代的特征，但调节亲代与后代控制后代表型平衡的表观遗传机制尚不清楚。我们测试了亲代和/或后代中的 DNA 甲基化是否介导了在两代中经历的环境线索的反应。
我们使用拟南芥，通过 5-氮杂胞苷化学处理和亲本甲基转移酶基因突变体遗传处理，同时改变亲代和后代的 DNA 甲基化，然后测量了亲代和后代世代中模拟树冠遮荫对后代发芽的反应。
我们首先发现，后代的发芽反应受亲代而非种子去甲基化的影响。我们进一步发现，亲代去甲基化在低（Cvi-1）到中（Col）休眠的种子中逆转了树冠的亲代效应，但在高休眠（Cvi-0）的种子中消除了亲代效应。去甲基化通过抑制在白光（Cvi-1）或树冠下成熟的种子的发芽，或者通过增加在树冠下成熟的种子的发芽来实现。亲代甲基化的破坏也阻止了种子对自身光环境的反应，在一种基因型（Cvi-0，休眠最多）中，但它使种子能够对另一种基因型（Cvi-1，休眠最少）的自身环境做出反应。使用突变体基因型，我们发现 CG 和非 CG DNA 甲基化都参与了亲代对种子发芽的影响。
亲代甲基化状态比后代自身的甲基化状态更能强烈影响种子的发芽，并且它以特定于基因型的方式影响种子对亲代和后代环境的反应。
