Paramutation is a form of non-Mendelian inheritance in which the expression of a paramutable allele changes when it encounters a paramutagenic allele. This change in expression of the paramutable alleles is stably inherited even after segregation of both alleles. While the discovery of paramutation and studies of its underlying mechanism were made with alleles that change plant pigmentation, paramutation-like phenomena are known to modulate the expression of other traits and in other eukaryotes, and many cases have probably gone undetected. It is likely that epigenetic mechanisms are responsible for the phenomenon, as paramutation forms epialleles, genes with identical sequences but different expression states. This could account for the intergenerational inheritance of the paramutated allele, providing profound evidence that triggered epigenetic changes can be maintained over generations. Here, we use a case of paramutation that affects a transgenic selection reporter gene in tetraploid Arabidopsis thaliana. Our data suggest that different types of small RNA are derived from paramutable and paramutagenic epialleles. In addition, deletion of a repeat within the epiallele changes its paramutability. Further, the temperature during the growth of the epiallelic hybrids determines the degree and timing of the allelic interaction. The data further make it plausible why paramutation in this system becomes evident only in the segregating F2 population of tetraploid plants containing both epialleles. In summary, the results support a model for polyploidy-associated paramutation, with similarities as well as distinctions from other cases of paramutation.

中文翻译：

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拟南芥中与多倍体相关的突变是由小RNA，温度和等位基因结构决定的

变异是非孟德尔遗传的一种形式，其中，可变异等位基因的表达在遇到副致突变等位基因时会发生变化。即使在两个等位基因分离之后，该可变异等位基因表达的这种变化也被稳定地遗传。虽然通过改变植物色素沉着的等位基因进行了突变发现及其潜在机理的研究，但已知类似突变的现象可以调节其他性状和其他真核生物的表达，而且许多病例可能未被发现。表观遗传机制可能是造成这种现象的原因，因为突变形成了等位基因，即具有相同序列但表达状态不同的基因。这可以解释突变等位基因的代际遗传，提供了触发的表观遗传变化可以世代相传的深刻证据。在这里，我们使用一个影响四倍体拟南芥中转基因选择报告基因的变异突变案例。我们的数据表明，不同类型的小RNA来源于可突变的和可突变的表位等位基因。另外，删除等位基因内的重复序列会改变其超变异性。此外，在等位基因杂种的生长过程中的温度决定了等位基因相互作用的程度和时间。数据进一步证明了为什么该系统中的突变仅在包含两个等位基因的四倍体植物的分离F2群体中才变得明显。总而言之，结果支持多倍体相关的变异模型，