Physiological Responses of Wheat (Triticum Aestivum L.) –Aegilops Sharonensis Introgression Lines to Excess Copper

Two wheat lines (TL3 and TL5) derived from selection for Cu tolerance among wheat – Aegilops sharonensis hybrids were compared when grown as hydroponics at zero (control), 10⁻⁶ and 10⁻⁵  m CuSO₄. The morphometric measurements showed that the line TL5 with a more inhibited root system under 10⁻⁶  m CuSO₄ had a less inhibited shoot growth under 10⁻⁵  m CuSO₄ as compared to TL3. The decreased maximum efficiency of photosystem II and the more pronounced trend towards increased catalase activity suggested that despite the better shoot growth, the leaves of TL5 were more functionally injured. The increased content of carotenoids at excess Cu and the higher peroxidase and catalase activities of TL3 in control plants might contribute to its better stress tolerance. While no significant changes in enzyme activities were found at 10⁻⁶  m Cu, at 10⁻⁵  m the activities tended to increase. Although the close values of free phenolics concentrations in control plants, at Cu excess their content was higher in TL5 compared to TL3. The free phenolics content in roots at 10⁻⁶  m Cu decreased, and although higher at 10⁻⁵  m Cu, it remained below the control in TL3, and above the control in TL5. From the obtained results TL3 emerged to be more tolerant to excess Cu than TL5.