Evolution of gene expression in seasonal environments

Area of Science:

• Plant biology
• Evolutionary biology
• Genomics

Background:

• Biological activities are strongly influenced by seasonality.
• Phenology, the timing of biological events, is regulated by gene expression.
• Evolutionary dynamics of seasonal gene expression are not well understood.

Purpose of the Study:

• To investigate the evolutionary dynamics of seasonal gene expression.
• To compare genome-wide expression dynamics (molecular phenology) in four dominant Asian evergreen Fagaceae species.

Main Methods:

• Assembled high-quality reference genomes for four Fagaceae species.
• Performed seasonal transcriptomic profiling of 11,749 single-copy orthologous genes in leaf and bud tissues over two seasonal cycles.
• Analyzed gene expression patterns for conserved and rhythmic expression, including periodicity and seasonal peaks.

Main Results:

• Highly conserved gene expression was observed across species during winter (temperatures below ~10 °C).
• Rhythmic gene expression was more prevalent in buds (51.9%) than leaves (40.6%), with most exhibiting annual periodicity.
• Seasonal peaks of rhythmic genes were synchronized in winter but diverged during the growing season, reflecting species-specific phenological events.

Conclusions:

• Four Asian Fagaceae species share a conserved molecular calendar in winter.
• This conserved winter gene expression constrains the evolution of seasonal expression patterns.
• Divergence in growing season expression reflects species-specific adaptations to seasonal environments.