Table_2_Genome-Wide Identification of DNA Methylases and Demethylases in Kiwifruit (Actinidia chinensis).xlsx

DNA methylation plays an important role in a wide range of developmental and physiological processes in plants. It is primarily catalyzed and regulated by cytosine-5 DNA methyltransferases (C5-MTases) and a group of DNA glycosylases that act as demethylases. To date, no genome-scale analysis of the two kiwifruit (Actinidia chinensis) families has been undertaken. In our study, nine C5-MTases and seven DNA demethylase genes were identified in the kiwifruit genome. Through selective evolution analysis, we found that there were gene duplications in C5-MTases and demethylases, which may have arisen during three genome doubling events followed by selection during evolution of kiwifruit. Expression analysis of DNA methylases (C5-MTases) and demethylases identified changes in transcripts of DNA methylation and demethylation genes during both vegetative and reproductive development. Moreover, we found that some members of the two methylase/demethylase families may also be involved in fruit ripening and the regulation of softening. Our results help to better understand the complex roles of methylation/demethylation in plants and provide a foundation for analyzing the role of DNA methylation modification in kiwifruit growth, development and ripening.

DNA甲基化在植物广泛的发育与生理过程中发挥着关键作用。其催化与调控主要由胞嘧啶-5 DNA甲基转移酶（cytosine-5 DNA methyltransferases，C5-MTases）以及一类充当去甲基化酶的DNA糖苷酶完成。迄今为止，尚未针对中华猕猴桃（Actinidia chinensis）的这两个基因家族开展全基因组尺度的分析。在本研究中，我们从猕猴桃基因组中鉴定出9个C5-MTases基因与7个DNA去甲基化酶基因。通过选择性进化分析，我们发现C5-MTases家族与去甲基化酶家族均存在基因复制事件，此类复制事件可能起源于三次基因组加倍过程，并在猕猴桃的进化历程中受到选择作用。对DNA甲基化酶（C5-MTases）与去甲基化酶的表达分析显示，在营养发育与生殖发育阶段，DNA甲基化与去甲基化相关基因的转录水平均发生显著变化。此外，我们还发现这两个甲基化酶/去甲基化酶家族中的部分成员可能也参与了果实成熟与软化的调控过程。本研究结果有助于我们更深入地理解植物中甲基化与去甲基化的复杂生物学功能，并为解析DNA甲基化修饰在猕猴桃生长、发育及成熟过程中的作用奠定了重要基础。