Cadmium-induced physiological and genotoxic alterations in bryophyllum daigremontianum

Abstract

When evaluating the negative impacts of heavy metals in the environment, plants can be used as biological indicators in assessing damage done by bio-accumulation of heavy metals. For detecting the genotoxic effects of heavy metals, the RAPD-PCR technique is applied in plants. In this study, Blyophyllum daigremontianum was used as a bio-indicator for Cadmium (Cd) pollution. B. daigremontianum plantlets were obtained from bulbiliferous spurs. They were grown singly in standard pots and each of the experimental groups of 5 replicates were watered daily with Hoagland solution (20 ml) containing 0, 50, 100, 200 and 400 mu M Cd for two months. Plantlets were harvested at the end of the two-month experimental period and photosynthetic pigment (chlorophyll a, chlorophyll b, total chlorophyll, chlorophyll a/b and carotenoids) contents of B. daigremontianum in response to Cd stress were investigated. The comparison between unexposed and exposed B. daigremontianum groups revealed gradual reductions of photosynthetic pigment contents (-40.57% for chlorophyll a, -37.63% for chlorophyll b, -36.27% for total chlorophyll, -20.58% for chlorophyll a/b and -37.66% for carotenoids) at 400 pM and a genomic instability as Cd concentration increases. The results indicated that changes in RAPD-PCR profiles following Cd treatments included a variation in band intensities, a loss of normal bands, and the appearance of new bands compared to unexposed plantlets. Cd concentrations of the collected samples were measured by employing ICP-OES during the study. The concentrations of Cd at 400 mu M Cd treatment were increased significantly in leaves (-5.03 fold), stems (-6.28 fold) and roots (-3.90 fold) of B. daigremontianum. The present study evidences that as an investigation tool for environmental toxicology, the RAPD technique can be useful and can be applied as a suitable biomarker assay for the detection of genotoxic effects of Cd pollution on plants.