Morphoanatomy and Phenoplasticity of Cardamine hupingshanensis (Brassicaceae) Under Cadmium Stress

Using a soil culture method, this study investigated the morphoanatomical responses and phenotypic plasticity of Cardamine hupingshanensis (Brassicaceae) under different cadmium (Cd) concentrations. Root morphological indices initially increased at low Cd levels but decreased as Cd concentrations rose, exhibiting a low-promoting and high-inhibiting effect. Leaf morphology and biomass peaked at 5 or 10 mg kg-1 Cd before decreasing at higher concentrations but were still significantly higher than the control (P < 0.05). Anatomical structure analysis revealed no significant difference at 5 mg kg-1 Cd; however, at ≥ 100 mg kg-1 Cd, epidermal and spongy tissue thickness differed significantly from the control. Correlation analysis indicated a significant positive correlation between Cd concentration and epidermal and spongy tissue thickness but a negative correlation with palisade tissue thickness. The mean phenotypic plasticity index of C. hupingshanensis under Cd stress was 0.73, with root morphology exhibiting greater plasticity. These findings show the adaptability of C. hupingshanensis in cadmium-contaminated environments and its resilience under heavy metal stress.