A dynamic signaling path to chromatin-level control of plant drought response

As sessile organisms, plants display a high capacity for phenotypic adaptations allowing them to meet the constraints of a changing local environment. This plasticity notably originates from the aptitude of plants to adjust their development and physiology throughout their lifetime to reach an optimal trade-off between growth and fitness. As in all eukaryotes, dynamic control of plant gene expression in different cell types is dependent on multiple regulatory layers that often converge onto chromatin-based mechanisms. Dynamic control of chromatin composition and organization has a strong impact on the cellular transcriptional program, notably contributing to selective modulation of gene expression in a reversible manner. Chromatin state changes generally involve remodeling of nucleosome positioning, incorporation of nucleosomal and linker histone variants, and DNA and histone modifications recognized by cognate readers. Together, these processes modulate the access and activity of transacting factors such as transcription factors and RNA polymerases. Temporary shifts between transcriptionally permissive and repressive chromatin states rely on various mechanisms , among which is the rapid reversion of a ''responsive'' chro-matin status through active erasure of newly established features.