The aim of our work was to study the response of antioxidative enzymes, and antioxidants of tomato and eggplant roots to waterlogged conditions. The roots of four entries, eggplants EG117 and EG203, and tomatoes TNVEG 6 and L4422 (Lycopersicon pimpinellifolium Mill), were subjected to seven flooding treatments. A split-plot design with three replications was used. The activity of APX in roots significantly increased during the period of continuous waterlogging. Slight increases in total ASA, reduced ASA, GSH, and total glutathione contents in the roots were also observed throughout the entire waterlogging period. However, the activities of CAT, SOD and GR, and the contents of ASA, GSSG and alpha-tocopherol in the roots were unaffected by waterlogging. Entries responded differently to oxidative injury according to their various antioxidative systems. The results indicate that total ASA could be involved in flooding damage to tomato roots. Overall, following the waterlogging treatments, APX activity in the eggplants was generally higher than in the tomatoes. Our work suggests that the brownish roots of tomatoes induced by flooding may be the consequence of H2O2 scavenging possibly controlled by APX activity. The H2O2 scavenging system as represented by APX was clearly limiting or less efficient in the tomatoes, leading to an accumulation of H2O2. The ability to maintain a balance between the formation and detoxification of activated oxygen species appeared likely to increase the survival potential and the tolerance of the roots against varying oxidative stress. On the basis of our observations, we conclude that increased APX activity provides plant roots with increased waterlogged stress tolerance. (C) 2004 Elsevier Ireland Ltd. All rights reserved.
