Polyploidy drives structural and functional evolution in Camellia mitochondrial genomes.

Area of Science:

• Plant evolutionary biology
• Genomics
• Mitochondrial DNA evolution

Background:

• Whole-genome duplication (polyploidy) significantly impacts plant evolution.
• The co-evolving mitochondrial genome's response to polyploidy is understudied.
• The genus Camellia provides a model system due to its varied ploidy levels.

Purpose of the Study:

• Investigate the structural and molecular evolution of the mitochondrial genome in response to polyploidy.
• Understand the impact of whole-genome duplication on mitogenome size, gene content, and rearrangements.
• Explore molecular diversification and RNA editing patterns in polyploid Camellia.

Main Methods:

• Comparative mitogenomic analysis across a ploidy gradient (2×, 4×, 6×).
• Assessment of mitochondrial genome size, core gene content, and structural rearrangements.
• Identification and analysis of lineage-specific selection in metabolic genes and RNA editing patterns.

Main Results:

• Mitochondrial genome size and core gene content were conserved across ploidy levels.
• Polyploid Camellia species showed extensive genomic rearrangements compared to diploids.
• Lineage-specific selection was observed in metabolic genes; RNA editing was ploidy-independent.
• Numerous chloroplast-to-mitochondrion DNA transfers (MTPTs) were identified, with variable retention.

Conclusions:

• Core mitochondrial genome features are robust to polyploidization in Camellia.
• Structural flux and lineage-specific molecular evolution are key outcomes of polyploidy.
• Neutral processes and structural turnover significantly influence mitogenome evolution post-duplication.