Conserved genes, discordant structure: a pangenomic view of plant mitochondrial genome evolution

Plant mitochondrial genomes show highly conserved gene content but sharply discordant structure: synteny collapses almost entirely in vascular plants despite genome sizes spanning ~66 kb to over 19 Mb.

• Why it matters: Extreme size and structural heterogeneity across land plants has blocked a comparable, phylogeny-wide view of mitochondrial evolutionary dynamics.
• What they did: The study analyzed over 300 de-novo assembled and annotated plant mitochondrial genomes, using assembly-graph complexity metrics, recombination potential, and a hyper pangenome across the land plant phylogeny.
• The result: Phylogenetic mixed models identify genome size and interspersed repeat fraction as the strongest predictors of structural complexity, while nuclear-to-mitochondrial transfer (roughly three times more frequent than plastid-to-mitochondrial) does not drive genome expansion.