Proline and Glycinebetaine Confer Cadmium Tolerance on Tobacco Bright Yellow-2 Cells by Increasing Ascorbate-Glutathione Cycle Enzyme Activities

Abstract

Cadmium (Cd) stress significantly decreased membrane integrity and impaired the ascorbate (ASC)-glutathione (GSH) cycle in tobacco Bright Yellow-2 cells. Exogenous application of proline and glycinebetaine (betaine) significantly restored the membrane integrity and increased the activities of ASC-GSH cycle enzymes under Cd stress without maintenance of the rich ASC or GSH pools. Moreover, proline offered more efficient protection against Cd stress than betaine.