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Background <p>Whole-genome duplication (polyploidy) is a primary driver of plant evolution, yet its impact on the co-evolving mitochondrial genome remains poorly understood. The genus <i>Camellia</i>, with its diverse ploidy levels, offers an ideal system to investigate the resulting structural and molecular evolution of the mitogenome.</p> Results <p>Comparative mitogenomic analysis across a ploidy gradient (2×, 4×, 6×) revealed that mitochondrial genome size (900&#xa0;kb) and core gene content remained highly conserved despite significant nuclear genome expansion. However, polyploid species exhibited extensive genomic rearrangements compared to their diploid relatives, indicating substantial structural evolution. Lineage-specific selection was identified in metabolic genes, such as <i>sdh3</i>, suggesting molecular diversification of energy-related pathways. RNA editing patterns were independent of ploidy, maintaining a stable frequency and distribution of editing sites across all species, with Leucine being the most frequent conversion product. Additionally, we identified 17–22 chloroplast-to-mitochondrion DNA transfers (MTPTs), including 3–7 tRNA genes with intact structures. The retention of these fragments varied between lineages, reflecting neutral genomic flux rather than ploidy-dependent functional selection.</p> Conclusions <p>Our findings demonstrate that while core mitogenomic features are robust to polyploidization, structural flux and lineage-specific molecular shifts are prominent. This study highlights the role of neutral processes and structural turnover in mitogenome evolution following whole-genome duplication, providing insights into cytonuclear coordination in polyploid <i>Camellia</i>.</p>

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Polyploidy drives structural and functional evolution in Camellia mitochondrial genomes

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年1月28日

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  • Jianbin Gao,
  • Yuan Zeng,
  • Boyong Liao,
  • Zuoyun Yin,
  • Wei Wu,
  • Yongquan Li

摘要

Background

Whole-genome duplication (polyploidy) is a primary driver of plant evolution, yet its impact on the co-evolving mitochondrial genome remains poorly understood. The genus Camellia, with its diverse ploidy levels, offers an ideal system to investigate the resulting structural and molecular evolution of the mitogenome.

Results

Comparative mitogenomic analysis across a ploidy gradient (2×, 4×, 6×) revealed that mitochondrial genome size (900 kb) and core gene content remained highly conserved despite significant nuclear genome expansion. However, polyploid species exhibited extensive genomic rearrangements compared to their diploid relatives, indicating substantial structural evolution. Lineage-specific selection was identified in metabolic genes, such as sdh3, suggesting molecular diversification of energy-related pathways. RNA editing patterns were independent of ploidy, maintaining a stable frequency and distribution of editing sites across all species, with Leucine being the most frequent conversion product. Additionally, we identified 17–22 chloroplast-to-mitochondrion DNA transfers (MTPTs), including 3–7 tRNA genes with intact structures. The retention of these fragments varied between lineages, reflecting neutral genomic flux rather than ploidy-dependent functional selection.

Conclusions

Our findings demonstrate that while core mitogenomic features are robust to polyploidization, structural flux and lineage-specific molecular shifts are prominent. This study highlights the role of neutral processes and structural turnover in mitogenome evolution following whole-genome duplication, providing insights into cytonuclear coordination in polyploid Camellia.