Genomic insights into positive selection during barley domestication

Area of Science:

• Molecular evolutionary biology
• Plant genetics
• Crop domestication studies

Background:

• Cultivated barley (Hordeum vulgare) is a vital crop for feed, food, and beverages.
• Barley serves as a model organism for molecular evolutionary research.
• Limited research exists on the evolutionary trajectories of gene types during barley domestication.

Purpose of the Study:

• To investigate the evolutionary divergence between positively selected genes (PSGs) and negatively selected genes (NSGs) in barley.
• To compare the evolutionary rates, properties, expression patterns, and diversity of PSGs and NSGs.
• To identify candidate PSGs potentially involved in barley domestication and breeding.

Main Methods:

• Calculation of nonsynonymous (Ka) to synonymous (Ks) substitution rates for orthologous genes.
• Comparative analysis of evolutionary rates, gene structure, expression, and nucleotide diversity.
• Identification and characterization of positively and negatively selected genes.

Main Results:

• PSGs exhibited faster evolution, fewer exons, lower GC content, and shorter lengths compared to NSGs.
• PSGs displayed lower expression levels, higher tissue specificity, and weaker codon usage bias.
• PSGs experienced a more severe genetic bottleneck, with candidate genes linked to plant growth and development.

Conclusions:

• The study provides novel insights into the evolutionary divergence of PSGs and NSGs during barley domestication.
• Findings highlight the distinct evolutionary paths taken by different gene types in barley.
• Identified candidate PSGs offer targets for future functional studies and molecular breeding in barley.