Phenylpropanoid Pathway Response to Cadmium and Lead Stress in Phaselous vulgaris Roots and Leaves

Abstract

Phenylpropanoid Pathway Response to Cadmium and Lead Stress in Phaselous vulgaris Roots and Leaves Heavy metals induce diverse morphological and physiological changes in plants, but the actual mechanisms leading to integrated responses are not well understood. For better understanding, the metabolic adaptation to Cd and Pb stress in Phaseolus vulgaris, the alterations in the phenylpropanoid pathway related enzymes, shikimate dehydrogenase (SKDH) and phenylalanine ammonia lyase (PAL), and also total phenolics and flavonoid contents were studied in the roots and leaves. It was found that Cd and Pb treatments caused an increase in the activities of SKDH and PAL, and in the content of total phenolics and flavonoids. In the roots and leaves of Cd-treated plants, SKDH activities were induced by low concentrations, while the highest activities were observed in the roots treated with Pb and in contrast, were inhibited in the leaves. PAL activity showed similar alterations in a dose-dependent way both Cd and Pb-treated roots and leaves of P. vulgaris. After the 3rd day, the decreases in the enzyme activities, and total phenolics and flavonoids content suggest that the stricter mechanism than phenolics, lignin synthesized from the accumulated phenolics to overcome metal-induced stress. Taking all the data together, it was demonstrated in this work that phenylpropanoid pathway was actively regulated by P. vulgaris plants in response to heavy metal stress.