Authors: Soon Lim YunHee Kim SunHyung Kim SukYoon Kwon HaengSoon Lee JinSeog Kim KwangYun Cho KeeYoeup Paek SangSoo Kwak
Publish Date: 2007/01/13
Volume: 19, Issue: 3, Pages: 227-239
Abstract
Oxidative stress is one of the major factors causing injury to plants exposed to environmental stress Transgenic sweetpotato Ipomoea batatas L Lam cv Yulmi plants with an enhanced tolerance to multiple environmental stresses were developed by expressing the genes of both CuZn superoxide dismutase CuZnSOD and ascorbate peroxidase APX under the control of an oxidative stressinducible SWPA2 promoter in the chloroplasts of sweetpotato plants referred to as SSA plants SSA plants were successfully generated by the particle bombardment method and confirmed by PCR analysis When leaf discs of SSA plants were subjected to 5 μM methyl viologen MV they showed approximately 45 less damage than nontransformed NT plants When 200 μM MV was sprayed onto the whole plants SSA plants showed a significant reduction in visible damage compared to leaves of NT plants which were almost destroyed The expression of the introduced CuZnSOD and APX genes in leaves of SSA plants following MV treatment was significantly induced thereby reflecting increased levels of SOD and APX in the chloroplasts APX activity in chloroplast fractions isolated from SSA plants was approximately 15fold higher than that in their counterparts from NT plants SSA plants treated with a chilling stress consisting of 4°C for 24 h exhibited an attenuated decrease in photosynthetic activity Fv/Fm relative to NT plants furthermore after 12 h of recovery following chilling the Fv/Fm of SSA plants almost fully recovered to the initial levels whereas NT plants remained at a lower level of Fv/Fm activity These results suggest that SSA plants would be a useful plant crop for commercial cultivation under unfavorable growth conditions In addition the manipulation of the antioxidative mechanism in chloroplasts can be applied to the development of various other transgenic crops with an increased tolerance to multiple environmental stressesThis research was supported by grants from the BioGreen21 Program Rural Development Administration Korea from the Environmental Biotechnology National Core Research Center KOSEF/MOST Korea and from the International Collaboration Project Ministry of Science and Technology MOST Korea We are grateful to Prof Ray A Bressan Purdue University for his valuable comments to the manuscript
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