Comparative Analysis of Araceae Mitochondrial Genomes: Implications for Adaptation to Ecological Transitions in...

Background/Objectives: Plant mitogenomes display remarkable variation in size, structure, and gene content, yet their evolutionary causes remain unclear. Araceae, the most significant family within Alismatales, encompasses both aquatic and terrestrial lineages, providing an excellent system for studying how ecological shifts influence mitogenome evolution. Methods: We assembled and annotated four new mitogenomes using both short- and long-read sequencing, including three aquatic taxa (Pistia stratiotes L., Spirodela intermedia W. Koch, Wolffia australiana (Benth.) Hartog & Plas) and one terrestrial species (Amorphophallus konjac K. Koch). Along with five previously published mitogenomes, we performed comparative analyses across nine Araceae species. Results: These mitogenome sizes varied from ~178 kb to ~877 kb, consisting of one to 19 circular molecules, with aquatic species generally having smaller and simpler structures. Plastid-derived sequences (MTPTs) contributed 1.2-10.6% of genome content, peaking in Zantedeschia aethiopica (L.) Spreng. Despite significant structural heterogeneity, all species maintained core respiratory genes under strong purifying selection, while ribosomal protein-coding genes showed lineage-specific loss. RNA editing ranged from 363 to 772 sites per mitogenome, with the number of sites independent of mitogenome size. Conclusions: Overall, this study uncovers the dynamic evolutionary patterns of Araceae mitogenomes and offers a framework for understanding how habitat shifts between aquatic and terrestrial environments influence mitogenome diversity in plants.