Effect of cadmium stress on the polyphenol content, morphological, physiological, and anatomical parameters of common bean (Phaseolus vulgaris l.)

Abstract

Cadmium (Cd) is one of the most notable heavy metals because of its high mobility and toxicity towards plants. In the present study, we aimed to evaluate the effect of cadmium on growth, physiological parameters, anatomical changes and phenolic compounds content in Phaseolus vulgaris L plant. Seedlings were exposed to cadmium at 0.25; 0.5 and 1 g.l-1 for 21 days. Results indicated that cadmium significantly decreased percent seed germination, embryonic radical elongation, plant dry weight, stem/root length and numbers of leaves and lateral roots. Cadmium also induced a decrease in chlorophyll and protein content with all treatments; however, sugar and proline increased significantly with 1 g.l-1. Total phenolic content increased by around 43% and 32% in the above ground part and roots respectively. Flavonoids, flavonols, hydrolysable tannins and condensed tannins showed a significant increase with higher cadmium concentration. Cadmium also changed plant root and stem anatomy; a decrease in both number and size of xylem vessels and a delay in xylem differentiation were observed.