AUTHOR=Huang Kerui , Xu Wenbo , Hu Haoliang , Jiang Xiaolong , Sun Lei , Zhao Wenyan , Long Binbin , Fan Shaogang , Zhou Zhibo , Mo Ping , Jiang Xiaocheng , Tian Jianhong , Deng Aihua , Xie Peng , Wang Yun 

TITLE=Super-large record-breaking mitochondrial genome of Cathaya argyrophylla in Pinaceae

JOURNAL=Frontiers in Plant Science

VOLUME=Volume 16 - 2025

YEAR=2025

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2025.1556332

DOI=10.3389/fpls.2025.1556332

ISSN=1664-462X

ABSTRACT=IntroductionMitochondrial genomes (mitogenomes) in Pinaceae are notable for their large size and complexity. This study investigates the mitogenome of the critically endangered Cathaya argyrophylla to understand the drivers of its exceptional genome expansion.MethodsWe sequenced, assembled, and annotated the C. argyrophylla mitogenome. Comparative analyses were performed against other Pinaceae species and gymnosperms, examining repeat sequences, transposable elements (LINEs, LTRs), RNA editing events, chloroplast-derived sequence transfers (mtpts), and nuclear genome homology.ResultsThe C. argyrophylla mitogenome is a record-breaking 18.99 Mb. While C. argyrophylla and other extremely large Pinaceae mitogenomes possess substantial repeats and elevated transposon activity, these factors alone do not explain their size. Significant incorporation of mtpts was observed. Additionally, large mitogenomes exhibited distinct RNA editing patterns and reduced nuclear homology compared to smaller genomes.DiscussionMassive Pinaceae mitogenomes are characterized by a combination of features: substantial repeat content, elevated transposon activity, extensive plastid sequence integration, and distinct RNA editing and nuclear homology patterns. This comprehensive analysis enhances our understanding of plant mitogenome evolution and provides a genomic foundation for C. argyrophylla conservation and potential applications.