Oxidative stress response and glutathione linked enzymes in relation to growth of sugarcane plants exposed to hexavalent chromium

Abstract

Effect of hexavalent chromium (Cr6+) was seen onSaccharum species hybrid (cv. CoSe 92423) grown for 27 days in sand culture supplemented with 30,60 and 90 ppm of chromium. The inhibitory response of Cr6+ on shoot and root growth was concentration dependent. The stimulation in germination per cent was observed at 30 ppm which did not sustain at higher concentrations. Despite reduction in growth, dry matter production increased substantially with increase in Cr concentration after 27 days exposure to Cr6+. Significant increase in lipid peroxidation and tissue concentration of H2O2 occurred in plants exposed to 30, 60 and 90 ppm Cr6+. Effect of Cr6+ on Glutathione reductase (GSSG-R) and ascorbate peroxidase (APX) activity in roots and leaves was differential. Glutamyl cysteine synthetase activity increased up to 60 ppm treatment but it decreased slightly at 90 ppm, nevertheless, it remained higher than the control. The results suggested that Cr6+ induced depression in plant growth of sugarcane to be a function of increased cellular accumulation of Cr, despite increase in the activities of some of the antioxidative enzymes. One positive effect was observed in the form of increased germination per cent of the sugarcane buds at 30 ppm, possibly due to increased antioxidative enzyme activities and operation of glutathione-ascorbate cycle to scavenge H2O2.