Investigating adaptation to environmental variability in forest trees through molecular phylogenetic analysis

Area of Science:

• Molecular Evolution
• Plant Biology
• Genomics

Background:

• Abiotic stresses significantly impact forest ecosystems and tree survival.
• Understanding the molecular basis of abiotic stress adaptation is crucial for predicting forest resilience.

Purpose of the Study:

• To investigate the evolutionary dynamics of abiotic stress response genes in 13 key European forest species.
• To identify factors driving distinct adaptation pathways in angiosperms and conifers.

Main Methods:

• Molecular phylogenetic analysis of 616 abiotic stress-related genes across 13 European forest species.
• Reconstruction of phylogenetic relationships using the maximum likelihood method.
• Calculation of synonymous (Ks) and nonsynonymous (Ka) substitution rates to assess evolutionary pressures.

Main Results:

• Angiosperms (347 genes) possess more stress-responsive genes than conifers (269 genes).
• Drought stress involved more shared genes than freezing stress.
• Conifers showed a higher Ka/Ks ratio, suggesting stronger adaptive evolution, despite lower substitution rates.

Conclusions:

• Distinct evolutionary patterns exist in molecular responses to abiotic stress between angiosperms and conifers.
• Lower substitution rates in conifers may be linked to larger genomes and ancient divergence.
• Conserved stress response mechanisms are evident across diverse lineages, indicated by Ka/Ks values below unity.