Enhanced tolerance of transgenic sweetpotato plants that express both CuZnSOD and APX in chloroplasts to methyl viologen-mediated oxidative stress and chilling
- 532 Downloads
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 stress-inducible 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 non-transformed (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 15-fold 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 stresses.
KeywordsAscorbate peroxidase Chilling stress Chloroplast Oxidative stress Superoxide dismutase Sweetpotato
CuZn superoxide dismutase
Sweetpotato peroxidase anionic 2
This 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.
- Kimura T, Otani M, Noda T, Ideta O, Shimada T, Saito A (1999) Decrease of amylase content in transgenic sweetpotato. Breed Res 1:142Google Scholar
- Kwon EJ, Kwon SY, Kim MZ, Lee JS, Ahn YS, Jeong BC, Kwak SS, Lee HS (2002a) Plant regeneration of major cultivars of sweetpotato (Ipomoea batatas) in Korea via somatic embryogenesis. Korean J Plant Biotechnol 29:189–192Google Scholar
- Li Y, Deng XP, Kwak SS, Tanaka K (2006) Drought tolerance of transgenic sweetpotato expressing both Cu/Zn superoxide dismutase and ascorbate peroxidase. J Plant Physiol Mol Biol 32:451–457Google Scholar
- Nakano Y, Asada K (1981) Hydrogen peroxidase is scavenged by ascorbate-specific peroxidase in spinach chloroplasts. Plant Cell Physiol 22:867–880Google Scholar
- Otani M, Shimada T, Kimura T, Saito A (1998) Transgenic plants production from embryogenic callus of sweetpotato (Ipomoea batatas (L.) Lam.) using Agrobacterium tumefaciens. Plant Biotechnol 15:11–16Google Scholar
- Prakash CS (1994) Sweet potato biotechnology: progress and potential. Biotechnol Dev Mon 18:19–22Google Scholar
- Sanford JC, Smith FD, Russell JA (1992) Optimizing the biolistic process for different biological applications. Methods Enzymol 217:485–509Google Scholar
- Yun BW, Huh GH, Lee HS, Kwon SY, Jo JK, Kim JS, Cho KY, Kwak SS (2000) Differential resistance to methyl viologen in transgenic tobacco plants that express sweetpotato peroxidase. J Plant Physiol 156:504–509Google Scholar