Cytogenetic and biochemical investigations to study the response of Vigna radiata to cadmium stress

Abstract

A study was carried out on root tips and leaves of Vigna radiata, 15 days old plantlets grown in nutrient Hoagland media were exposed to various levels of cadmium chloride (0.05, 0.10 and 0.50 mM) for 48 and 72 h. The plant tissues were analyzed for mitotic index, chromosomal variations, root-shoot ratio, leaf area, chlorophyll estimation, and the activity of nitrate content, nitrate reductase (NR), soluble protein and proline content. A number of chromosomal variations such as laggard chromosomes, anaphasic bridges, and unidistribution of chromatin material were observed in root tips. A reduction in mitotic index, root-shoot ratio, area of leaf and chlorophyll estimation was observed at all concentrations of cadmium. Moreover, activity of nitrate reductase (NR), nitrate content and soluble protein content was also found to be decreased. However, rate of proline content was found to be increased on increasing the concentration of cadmium. An increase in the levels of proline suggests its possible incorporation in synthesis of the phytochelatins and metallothioneins to sequester and combat Cd-stress. Key words: Vigna radiata, phytochelatins, cytogenetics, cadmium.