Mitochondrial Splicing Efficiency Is Lower in Holoparasites Than in Free-Living Plants.

This article focuses on the splicing efficiency (SEf) of mitochondrial group II introns in free-living and holoparasitic angiosperms, examining how these differences relate to mitochondrial gene expression and plant lifestyle. The study analyzed 25 group II introns across 15 species, finding that holoparasitic plants exhibit significantly lower SEf compared to free-living plants, which may be linked to their loss of photosynthesis and parasitic lifestyle rather than horizontal gene transfer (HGT). Despite frequent HGT events in holoparasites, no correlation was found between foreign gene origin and reduced SEf, and nuclear-encoded splicing factors remained native. These findings suggest that relaxed selection pressure associated with the holoparasitic lifestyle influences mitochondrial intron splicing, providing insights into the molecular evolution of parasitic plants and organelle gene regulation.