Altered Antioxidant Physiology and Cadmium Partitioning in Arabidopsis F2 Descendants of Chromium-Exposed Ancestors

Ancestral environmental stress can influence descendant phenotypes, yet the physiological traits underlying such effects remain poorly understood, particularly in response to heterologous stress. We investigated whether chronic chromium (Cr) exposure in the parental generation is associated with persistent physiological differences in Arabidopsis thaliana F2 descendants. Wild-type plants were exposed to 2.5 μM hexavalent chromium [Cr(VI)] supplied as potassium dichromate (K₂Cr₂O₇) from the seedling stage until seed set. The resulting F2 lineage derived from chromium-exposed ancestors (2.5F2) was subsequently grown under control conditions or challenged with salinity (25 mM NaCl) or cadmium stress (25 μM Cd). Growth traits, biomass allocation, antioxidant enzyme activities, total soluble proteins, and elemental composition were assessed at the flowering stage. Significant lineage × treatment interactions were observed for root growth, APX activity, and cadmium partitioning. Under cadmium stress, 2.5F2 plants maintained longer roots and higher shoot biomass than wild-type plants. The most pronounced lineage-specific difference was observed for ascorbate peroxidase (APX) activity: whereas wild-type plants exhibited strong stress-induced APX activation, the 2.5F2 lineage maintained elevated APX activity across all treatments in both shoots and roots. Elemental analysis further revealed altered metal homeostasis, with 2.5F2 plants accumulating less cadmium in roots but more in shoots, resulting in a higher shoot-to-root cadmium ratio, while root iron concentrations remained consistently higher across treatments. These findings indicate that descendants of chromium-exposed ancestors exhibit persistent physiological differences characterized by elevated antioxidant activity, altered cadmium partitioning, and improved maintenance of root growth under cadmium stress.