Biased Gene Introgression and Adaptation in the Face of Chloroplast Capture in Aquilegia amurensis.

This article investigates the mechanisms and evolutionary consequences of chloroplast capture—a process where a plant species acquires the plastid genome of another through hybridization and introgression—using three Aquilegia (columbine) species from Northeast China: A. amurensis, A. parviflora, and A. japonica. The study demonstrates that A. amurensis captured the plastome of A. parviflora, supported by cytonuclear discordance and gene flow analyses, and that nuclear genes encoding cytonuclear enzyme complexes (CECs), which interact with organelles, are preferentially retained from the chloroplast donor species during introgression. Functional enrichment revealed overrepresentation of terpene synthase activity genes among introgressed loci, correlating with similarities in floral terpene profiles between A. amurensis and A. parviflora, suggesting a role for chloroplast capture in adaptive divergence. Overall, the findings clarify how cytonuclear coevolution following chloroplast capture can drive species differentiation and functional adaptation in plants.