多倍体植物的表观遗传现象

表观遗传现象是指基因表达发生改变但不涉及DNA序列的变化, 它存在于许多植物的多倍体化过程中，而且能够在代与代之间传递。表观遗传变异包括基因沉默、DNA甲基化、核仁显性、休眠转座子激活和基因组印记等方面。这种现象可能是由于基因组间的相互作用直接诱发基因沉默或基因表达改变所致；也可能由DNA甲基化之外的组蛋白编码的改变引起；或者与甲基化不足、染色质重组或转座子激活等有关。表观遗传变异在提高基因表达的多样性，引起遗传学和细胞学上的二倍化，以及促进基因组间的相互协调等方面起着重要作用。文章综述了植物多倍体化过程中的表观遗传现象及其在多倍体植物基因组进化中的作用，并在此基础上提出了今后在这方面的研究途径。

Epigenetic Phenomena of Plant Polyploids

Epigenetic phenomena, heritable changes in phenotype, and hence in gene regulation, but not in DNA sequence, occur in the process of polyploidization in many plants. These phenomena include gene silencing, DNA methylation, nucleolar dominance, transposable elements activation and genomic imprinting. Epigenetic phenomena might be caused by gene silencing or alternative gene expression from intergenomic interaction. These could also be induced from the changes of histone coding, without DNA methylation. Furthermore, hypomethylation, chromatin reconstitution or transposable element activation could contribute to epigenetic phenomena. These modifications may give rise to the diversification of gene expressing, to the genetic and cytological diploidization, as well as to intergenomic coordnation. This paper reviews epigenetic phenomena in many plants and their influence on evolution of plant genome, thus hint the likely pathway of research in this field.