Genetius

The study characterizes all seven malic enzyme genes in tomato, analyzing their tissue-specific expression, temperature and ethylene responsiveness, and linking specific isoforms to metabolic processes such as starch and lipid biosynthesis during fruit development. Phylogenetic, synteny, recombinant protein biochemical assays, and promoter analyses were used to compare tomato enzymes with Arabidopsis counterparts, revealing complex evolutionary dynamics that decouple phylogeny from functional orthology.

The study investigates the regulation and function of mitochondrial alternative oxidase (AOX) during tomato fruit ripening, revealing that AOX activity peaks at the breaker stage and becomes the dominant pathway for climacteric respiration, driven by increased TCA cycle intermediates rather than gene expression. Using CRISPR‑Cas9 aox1a mutants, the authors show that loss of AOX disrupts ripening‑related metabolite profiles, underscoring AOX’s critical role in supporting ethylene and carotenoid biosynthesis.