The study tests whether heavy‑metal stress contributed to maize domestication by exposing teosinte (Zea mays ssp. parviglumis) and the Palomero toluqueno landrace to sublethal copper and cadmium, then analysing genetic diversity, selection signatures, and transcriptomic responses of three chromosome‑5 heavy‑metal response genes (ZmHMA1, ZmHMA7, ZmSKUs5). Results reveal strong positive selection on these genes, heavy‑metal‑induced phenotypes resembling modern maize, and up‑regulation of Tb1, supporting a role for volcanic‑derived metal stress in early maize evolution.

The study investigated the evolution of the rubisco large subunit (RbcL) across four plant clades using rbcL gene sequences, codon models, and protein structure predictions, finding widespread positive selection and convergent amino‑acid changes affecting side‑chain polarity. Phylogenetic comparative analyses linked higher protein stability to warmer growing‑season temperatures, though this relationship weakened after accounting for phylogeny.