# The CLASSY family controls tissue-specific DNA methylation patterns in Arabidopsis

## TL;DR

This paper shows how CLSY proteins control tissue-specific DNA methylation patterns in Arabidopsis, especially in ovules, and how their absence can shift epigenetic landscapes.

## Contribution

The study reveals that CLSY proteins generate epigenetic diversity by combining locus-specific targeting with tissue-specific expression.

## Key findings

- CLSY3 and CLSY4 control DNA methylation at loci with a conserved DNA motif in ovules.
- Mutants lacking specific CLSYs shift the epigenetic landscape between tissues.
- CLSYs contribute to substantial epigenetic diversity during plant development.

## Abstract

DNA methylation shapes the epigenetic landscape of the genome, plays critical roles in regulating gene expression, and ensures transposon silencing. As is evidenced by the numerous defects associated with aberrant DNA methylation landscapes, establishing proper tissue-specific methylation patterns is critical. Yet, how such differences arise remains a largely open question in both plants and animals. Here we demonstrate that CLASSY1-4 (CLSY1-4), four locus-specific regulators of DNA methylation, also control tissue-specific methylation patterns, with the most striking pattern observed in ovules where CLSY3 and CLSY4 control DNA methylation at loci with a highly conserved DNA motif. On a more global scale, we demonstrate that specific clsy mutants are sufficient to shift the epigenetic landscape between tissues. Together, these findings reveal substantial epigenetic diversity between tissues and assign these changes to specific CLSY proteins, elucidating how locus-specific targeting combined with tissue-specific expression enables the CLSYs to generate epigenetic diversity during plant development.

CLASSY (CLSY) proteins regulate DNA methylation at specific loci in the Arabidopsis genome. Here the authors show that the CLSYs also control tissue-specific DNA methylation, including at siren loci in ovules, and that the lack of an individual CLSYs can shift the epigenetic landscape between tissues.