The activities of antioxidant enzymes in response to oxidative stresses and hormones in paraquat-tolerant Rehmannia glutinosa plants.
All members of R. glutinosa show the unique characteristic of intrinsic tolerance to paraquat (PQ). Antioxidant enzymes have been proposed to be the primary mechanism of PQ resistance in several plant species. Therefore, the antioxidant enzyme systems of R. glutinosa were evaluated by comparatively analyzing cellular antioxidant enzyme levels, and their responses of oxidative stresses and hormones. The levels of ascorbate peroxidase (APX), glutathione reductase (GR), non-specific peroxidase (POX), and superoxide dismutase (SOD) were 7.3-, 4.9-, 2.7- and 1.6-fold higher in PQ-tolerant R. glutinosa than in PQ-susceptible soybeans. However, the activity of catalase (CAT) was about 12-fold higher in the soybeans. The activities of antioxidant enzymes reduced after PQ treatment in the two species, with the exception of POX and SOD in R. glutinosa, which increased by about 40 %. Interestingly, the activities of APX, SOD and POX in R. glutinosa, relative to those in soybeans, were further increased by 49, 67 and 93 % after PQ treatment. The considerably higher intrinsic levels, and increases in the relative activities of antioxidant enzymes in R. glutinosa under oxidative stress support the possible role of these enzymes in the PQ tolerance of R. glutinosa. However, the relatively lower levels of SOD versus PQ tolerance, and the mixed responses of antioxidant enzymes to stresses and hormones, suggest a possible alternative mechanism(s) for PQ tolerance in R. glutinosa.
Department of Horticulture, Jeollabuk-do Agricultural Research and Extension Services, Iksan 570-704, Korea.
Dong Geun
DG
Choi
Nam Hee
NH
Yoo
Chang Yeon
CY
Yu
Benildo
B
de Los Reyes
Song Joong
SJ
Yun
D000975:Antioxidants / Q000378:metabolism*; D060387:Ascorbate Peroxidases; D002374:Catalase / Q000378:metabolism; D004351:Drug Resistance; D005980:Glutathione Reductase / Q000378:metabolism; D006540:Herbicides / Q000494:pharmacology; D018384:Oxidative Stress / Q000502:physiology*; D010269:Paraquat / Q000494:pharmacology*; D010544:Peroxidases / Q000378:metabolism; D010937:Plant Growth Regulators / Q000494:pharmacology*; D018515:Plant Leaves / Q000187:drug effects / Q000201:enzymology; D032267:Rehmannia / Q000187:drug effects / Q000201:enzymology* / Q000378:metabolism; D013025:Glycine max / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D013482:Superoxide Dismutase / Q000378:metabolism
D000975:Antioxidants; D006540:Herbicides; D010937:Plant Growth Regulators; D010544:Peroxidases; D060387:Ascorbate Peroxidases; D002374:Catalase; D013482:Superoxide Dismutase; D005980:Glutathione Reductase; D010269:Paraquat