Alleviation of Copper-and Cadmium-Induced Suppression of Barley (Hordeum Vulgare L.) Seedling Growth by Proline

In the present study, it was examined whether proline could alleviate the suppression of copper-or cadmium-induced suppression of seedling growth in barley (Hordeum vulgare L.). Both Cu and Cd, applied in a range of 0–500 μM, inhibited the seedling growth of H. vulgare in terms of root length, shoot length and seedling fresh weight. Distinct organ-as well as metal-specific differences in the response were evident. The pretreatment of caryopses with proline (1, 10 mM) led to partial alleviation of Cu-or Cd-induced suppression of seedling growth; the magnitude of alleviation was greater at 10 mM proline. Furthermore, proline was found to be more effective in reverting the inhibitory effects of Cu as compared to those of Cd. Such difference could inter alia be ascribed to the fact that Cu, a redox element, imposes oxidative stress more strongly that could be countered by proline. The findings are consistent with a role of proline in HM detoxification.