Ultrastructural deformation of plant cell under heavy metal stress in Gram seedlings

Nowadays, heavy metal pollution has become a serious environmental problem on global scale. The heavy metals are non-biodegradable in nature, which can easily accumulate in the organisms of lower trophic level, and enter to the human body system through food chain. From this backdrop, the present experiment highlighted the effect of three heavy metals (Cr, Pb, and Mn) in different concentrations (25, 50, and 75 ppm) on Cicer arietinum in terms of growth physiology, metal uptake, biochemistry, and ultrastructural deformation. The results showed that with increasing metals (Cr and Pb) concentrations from 25 ppm to 75 mg/L both root and shoot length decreased along with root and shoot biomass. However, Mn showed little improvement in all growth physiological parameters at 50 ppm concentration. Biochemical parameters also revealed that both Cr and Pb reduced 64.94 and 69.61% total chlorophyll, respectively, with respect to control. Chlorophyll a to b ratio was highest in Mn followed by Cr and Pb at higher concentration (75 ppm). Metal accumulation pattern indicated that Cr is less accumulated in root shoot and leaf compared to Mn and Pb in all the studied concentrations. However, accumulation of Mn in shoot was always higher compared to Pb in all studied concentrations. Ultrastructural damage was recorded highest for Cr in root, shoot and leaf at both 25 and 50 ppm concentration. However, at 75 ppm Pb showed highest deformation in root and leaf was observed.