Active DNA Demethylation in Plant Companion Cells Reinforces Transposon Methylation in Gametes

作者：Ibarra Christian A; Feng Xiaoqi; Schoft Vera K; Hsieh Tzung Fu; Uzawa Rie; Rodrigues Jessica A; Zemach Assaf; Chumak Nina; Machlicova Adriana; Nishimura Toshiro; Rojas Denisse; Fischer Robert L^*; Tamaru Hisashi; Zilberman Daniel

来源：Science, 2012, 337(6100): 1360-1364.

DOI：10.1126/science.1224839

The Arabidopsis thaliana central cell, the companion cell of the egg, undergoes DNA demethylation before fertilization, but the targeting preferences, mechanism, and biological significance of this process remain unclear. Here, we show that active DNA demethylation mediated by the DEMETER DNA glycosylase accounts for all of the demethylation in the central cell and preferentially targets small, AT-rich, and nucleosome-depleted euchromatic transposable elements. The vegetative cell, the companion cell of sperm, also undergoes DEMETER-dependent demethylation of similar sequences, and lack of DEMETER in vegetative cells causes reduced small RNA-directed DNA methylation of transposons in sperm. Our results demonstrate that demethylation in companion cells reinforces transposon methylation in plant gametes and likely contributes to stable silencing of transposable elements across generations.

• 出版日期2012-9-14