Protective role of gallic acid against cadmium-induced toxicity in snapdragon (Antirrhinum majus L.)

Abstract

This study aims to evaluate the anatomical adaptive strategies of Antirrhinum majus under cadmium (Cd) toxicity in the presence of exogenous gallic acid (GA). The experiment was designed as a CRD (completely randomized design) to assess the morphological and anatomical traits under different concentrations of Cd toxicity (0 mM, 20 mM, 40 mM, 60 mM, and 80 mM) along with two levels of GA (10 mM and 20 mM). It was hypothesized that A. majus developed structural adaptations to overcome Cd stress with exogenous GA. Morpho-anatomical attributes of A. majus were negatively affected due to Cd toxicity by disrupting nutrient uptake, inducing oxidative damage, inhibiting photosynthesis, and altering tissue structure. The results of this study showed that at 80 mM Cd, root length was reduced by 44%, and a 22% decline was assessed in shoot length. A decrease was observed in plant height by 57%, leaf area by 42%, and dry weight by 77% in the 80 mM Cd compared to the control group. Gallic acid at 10 mM improved growth attributes under Cd stress, and 20 mM GA offered the maximum resistance. Plant height, leaf area, and biomass were improved, and they followed similar trends. Anatomical parameters were also adversely affected under Cd stress. At 80 mM Cd, maximum reductions were noted in the thicknesses of epidermis (36%), cortex (22%), xylem (12%), phloem (79%), and pith (14%) compared to the control group. Conclusively, Cd stress alone severely impaired snapdragon’s morphology and anatomical structures, whereas 20 mM gallic acid application mitigated these adverse effects.