ISHS Acta Horticulturae 692: II International Symposium on Biotechnology of Tropical and Subtropical Species
MANIPULATION OF SUPEROXIDE DISMUTASE AND CATALASE TO ENHANCE SULFUR DIOXIDE TOLERANCE IN TRANSGENIC CHINESE CABBAGE |
| Authors: | J.C. Yiu, M.J. Tseng |
| Keywords: | SOD, CAT, co-transformation, visible injury, chloroplast, transit peptide |
| DOI: | 10.17660/ActaHortic.2005.692.11 |
| Abstract:
To evaluate the feasibility of using engineered antioxidant enzymes as an approach to improve the tolerance of plants to ambient stress, we have engineered transgenic Chinese cabbage plants that overproduce superoxide dismutase (SOD) and catalase (CAT). These enzymes convert superoxide radicals into water, and are believed to play a crucial role in antioxidant defense. The SOD and/or CAT isolated from maize were targeted either to the cytosol or to the chloroplast. Hypocotyl and cotyledon explants of Chinese cabbage were infected with an Agrobacterium strain (LBA4404) carrying a distinct disarmed T-DNA containing sod and/or cat gene. Transgenic plants were confirmed by PCR, northern hybridization and enzyme activities. Besides, the sod and cat genes could co-transfer into the same plantlet, and transcribed into RNA. Enhanced SOD or CAT activity in the cytosol or chloroplast, when expressed on their own, had only a minor effect on sulfur dioxide (SO2) tolerance. However, overproduction of both SOD and CAT in the cytosol and chloroplast resulted in a 3-4 fold reduction of visible SO2 injury. These results suggest that attempts to increase stress resistance by simply raising the activity of one of the antioxidant enzymes have not always been successful presumably because of the need for a balanced interaction of protective enzymes. These results clearly indicate that alterations in the expression of enzymes involved in reactive oxygen-intermediate scavenging can have significant metabolic effects and bring about the hope that this strategy, the co-transformation system, can be used to develop plants with increasing stress tolerance. | |
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