Epigenetic reprogramming drives the annual growth-dormancy cycle in Populus

Area of Science:

• Plant biology
• Epigenetics
• Molecular ecology

Background:

• Perennial plants in temperate and boreal regions rely on a seasonal growth-dormancy cycle for winter survival.
• This cycle is controlled by gene activity in the shoot apex, influenced by environmental cues and chromatin states.
• The precise epigenetic mechanisms governing seasonal responses in trees are not well understood.

Purpose of the Study:

• To characterize chromatin dynamics in Populus (poplar) shoot meristems throughout the annual growth-dormancy cycle.
• To investigate the role of Polycomb Repressive Complex 2 (PRC2) and LIKE HETEROCHROMATIN PROTEIN 1 (PtLHP1) in regulating seasonal transitions.
• To provide a comprehensive epigenetic landscape of seasonal growth regulation in trees.

Main Methods:

• Integration of data on chromatin accessibility, histone modifications (H3K27me3), and transcriptomic dynamics across five key seasonal stages.
• Analysis of chromatin reprogramming events in relation to transcriptomic changes.
• Manipulation of PtLHP1 expression in hybrid poplar to assess its impact on dormancy and bud break.

Main Results:

• Identified stage-specific and proximal-distal chromatin reprogramming events that correlate with transcriptomic shifts.
• Demonstrated that H3K27me3 deposition by PRC2 is crucial for regulating growth-dormancy transitions.
• Showed that manipulating PtLHP1 affects dormancy release and bud break, with PtLHP1 co-localizing with H3K27me3 regions.

Conclusions:

• The study elucidates the epigenetic landscape governing seasonal growth and dormancy in trees.
• PtLHP1 plays a role in maintaining H3K27me3 homeostasis during seasonal transitions.
• These findings offer molecular targets for understanding and potentially manipulating phenological plasticity in trees.