PT  - JOURNAL ARTICLE
AU  - Walker, James
AU  - Zhang, Jingyi
AU  - Liu, Yalin
AU  - Vickers, Martin
AU  - Dolan, Liam
AU  - Nakajima, Keiji
AU  - Feng, Xiaoqi
TI  - Extensive N4 Cytosine Methylation is Essential for <em>Marchantia</em> Sperm Function
AID  - 10.1101/2021.02.12.428880
DP  - 2021 Jan 01
TA  - bioRxiv
PG  - 2021.02.12.428880
4099  - http://biorxiv.org/content/early/2021/02/12/2021.02.12.428880.short
4100  - http://biorxiv.org/content/early/2021/02/12/2021.02.12.428880.full
AB  - 4-methylcytosine (4mC) is an important DNA modification in prokaryotes, but its relevance, and even presence in eukaryotes have been mysterious. Here we show that spermatogenesis in the liverwort Marchantia polymorpha involves two waves of extensive DNA methylation reprogramming. First, 5-methylcytosine (5mC), a well-known eukaryotic DNA modification, expands from transposons to the entire genome. Notably, the second wave installs 4mC throughout genic regions, covering over 50% of CG sites in sperm. 4mC is catalyzed by two novel methyltransferases (MpDN4MT1a and MpDN4MT1b) specifically expressed during late spermiogenesis. Deletion of MpDN4MT1s eliminates 4mC, alters the sperm transcriptome, and produces sperm with swimming defects. Our results reveal extensive 4mC in a eukaryote and define a new family of eukaryotic methyltransferases, thereby expanding the repertoire of functional eukaryotic DNA modifications.Competing Interest StatementThe authors have declared no competing interest.