Precise expression patterns of genes in time and space are essential for proper 
development of multicellular organisms. Dynamic chromatin conformation and 
spatial organization of the genome constitute a major step in this regulation to 
modulate developmental outputs. Polycomb repressive complexes (PRCs) mediate 
stable or flexible gene repression in response to internal and environmental 
cues. In Arabidopsis thaliana, LHP1 co-localizes with H3K27me3 epigenetic marks 
throughout the genome and interacts with PRC1 and PRC2 members as well as with a 
long noncoding RNA. Here, we show that LHP1 is responsible for the spreading of 
H3K27me3 towards the 3' end of the gene body. We also identified a subset of 
LHP1-activated genes and demonstrated that LHP1 shapes local chromatin topology 
in order to control transcriptional co-regulation. Our work reveals a general 
role of LHP1 from local to higher conformation levels of chromatin configuration 
to determine its accessibility to define gene expression patterns.