Influence of selenium on metallothionein gene expression and physiological characteristics of sugarcane plants

Abstract

Selenium (Se), one of the most widely distributed elements of the earth’s crust, is required in trace amounts for normal growth and development of biological activity but its increasing level in soil poses productivity problems in many crops including sugarcane. In the present investigation, a promising line of sugarcane (CoLk 94184) was used to assess the impact of selenium on growth, physio-biochemical attributes vis-a-vis expression of metallothionein (MT) gene. Single bud setts of sugarcane (Saccharum spp. hybrids) was planted with differential levels of selenium (sodium selenite) viz., 0, 10, 50 and 100 ppm under soil tray culture conditions. At higher concentrations (50 and 100 ppm Se), symptoms of metal toxicity as stunted growth, reduced plant height, vigor, root, shoot weight and leaf chlorosis were observed. Biochemical analysis revealed reduction in content of chlorophylls, carotenoids, proline and induction of lipid peroxidation in terms of malondialdehyde content and higher activity of peroxidase enzyme. qRT-PCR analysis indicated increase in expression of MT gene in leaf tissue with an increase in Se supply and highest expression was observed at 50 ppm Se. At 100 ppm supply, adverse effect of Se was very severe and a minor increase in expression of MT gene was observed. Results suggest that MT gene is related to the Se homeostasis which in turn helps in tolerance to Se toxicity in sugarcane.