Influence of copper ions on growth, lipid peroxidation, and proline and polyamines content in carrot rosettes obtained from anther culture

Effect of Cu (0.1, 1, 10, and 100 μM) on the regeneration of carrot (Daucus carota L.) androgenic embryos of var. Feria and 1014 breeding line as well as on polyamines (PAs), proline contents, lipid peroxidation and Cu accumulation after 16 and 24 weeks was studied. Generally, growth of Feria rosettes was better than that of the 1014 line. Significant increase in Cu content in tissues was observed in both cultures grown at the highest Cu concentration (100 μM). The dose-dependent increase in proline in the 16-week-old culture of Feria was observed, while in 1014 its level increased only at the highest applied Cu concentration. On the contrary, in the 24-week-old culture, significant increase in the proline content were observed at 100 and 10 μM Cu in Feria and in 1014 breeding lines, respectively. The decline in proline content and decrease in embryogenic ability in the line 1014 grown in the presence of the highest Cu concentration for 24 weeks may indicate that a certain threshold of intracellular Cu was crossed. Both in Feria and 1014 line, putrescine and spermidine were the most abundant free PAs. The increased content of proline and higher contents of the constitutive free putrescine and spermidine in Feria cultivated for 24 weeks at the highest Cu concentration point to better protection of this cultivar. Thus, it seems that the higher tolerance of Feria to oxidative stress (characterized by lower thiobarbituric acid reactive substances value) may result from higher constitutive level of PAs. These data confirm the suggestion that variations in PA levels depend not only on the concentrations of metals tested, but also on plant species and cultivars. The role of PAs and proline in the carrot cultures treated with Cu is discussed.