Genotoxic Effects of Heavy Metals on Mitotic Chromosomes of Trigonella Foenum-Graecum L.

Abstract

Lead, cadmium, and copper are common environmental pollutants in most industrialized countries. Soil with heavy metal pollution has raised concern in recent years due to its possible destructive effects on plants system. In the present investigation, we studied the genotoxic effect of lead, cadmium, and copper on mitotic chromosomes of Trigonella foenum-graecum L. for the first time. The root tips of T. foenum-graecum were treated with four graded concentrations (viz. 50, 100, 150, and 200 ppm) of lead, cadmium, and copper. After hydrolyzing the root end in hydrochloric acid solution, they were stained with acetocarmine. After squashing the root end, they were studied under a microscope. To this end, the mitotic index (MI) and the total percentage of abnormality (TAP%) were analyzed. Studying of the root end of T. foenum-graecum showed that this plant is diploid and its chromosomal base number is 2x=2n=16. Cytological monitoring revealed that Pd, Cd, and Cu exhibit mitodepressive behaviors at higher concentrations. Moreover, the mitotic index decreases, but the incidence of different anomalies, such as sticky chromosome, c-mitosis, micronucleus, laggard chromosome, bridge, and precocious movement, increase through increasing heavy metal concentration. Among the mitotic abnormalities observed in all treatments, the highest percentage was related to the sticky chromosome. The highest genotoxic potential was observed in the lead, followed by cadmium and copper. The results showed that heavy metal pollution led to a significant MI reduction and TAP% increase in root tip meristems of T. foenum-graecum. This should be considered as a risk warning of the environmental pollution on plants, especially medicinal plants.