Origin and evolution of the octoploid strawberry genome

Area of Science:

• Genomics
• Plant Biology
• Evolutionary Biology

Background:

• Cultivated strawberry (Fragaria × ananassa) is an octoploid hybrid, originating from the ancient hybridization of two wild species.
• These wild ancestors trace back to four diploid progenitor species that merged over a million years ago.

Purpose of the Study:

• To generate a high-quality, chromosome-scale genome assembly for cultivated octoploid strawberry.
• To elucidate the evolutionary history and origin of this complex allopolyploid.
• To investigate subgenome dynamics and identify the dominant subgenome influencing traits.

Main Methods:

• Chromosome-scale genome assembly of Fragaria × ananassa.
• Phylogenetic analysis to identify extant relatives of diploid progenitor species.
• Comparative genomics to examine subgenome composition and evolutionary dynamics.
• Gene expression and pathway analysis to determine subgenome functional contributions.

Main Results:

• A near-complete chromosome-scale assembly of the octoploid strawberry genome was achieved.
• Evidence supports a North American origin for cultivated strawberry.
• A single dominant subgenome was identified, characterized by higher gene content, expression, and biased homoeologous exchanges.
• The dominant subgenome significantly influences metabolomic and disease-resistance pathways.

Conclusions:

• The reference genome provides a foundational resource for understanding strawberry evolution.
• The identified dominant subgenome offers targets for improving desirable traits in cultivated strawberry.
• This work enables advanced molecular breeding strategies for enhanced strawberry varieties.