Medium salt strength induced changes in growth, physiology and secondary metabolite content in adventitious roots of Morinda citrifolia: the role of antioxidant enzymes and phenylalanine ammonia lyase.
In an attempt to improve growth and secondary metabolite production, and to understand the possible mechanism involved in relation to the changes in physiology and activities of antioxidant enzymes, we cultured Morinda citrifolia adventitious roots in different strength (0.25, 0.50, 0.75, 1.0, 1.5 and 2.0) of Murashige and Skoog (MS) medium supplemented with 5 mg l(-1) indole butyric acid and 30 g l(-1) sucrose. Quarter-strength MS medium was proven suitable for the production of both root biomass and secondary metabolites [anthraquinone (AQ), phenolics and flavonoids]. With the increasing salt strength, root growth and AQ accumulation decreased significantly. Higher (1.5 and 2 MS) salt strength provoked osmotic stress resulted in more than twofold free proline accumulation than lower salt strength treated roots and induced free radical scavenging activity. Phenylalanine ammonia lyase activity showed a positive correlation in relation to salt strength that leads to an increase in phenol biosynthesis in expense of AQ formation. The elevated catalase (CAT), guaiacol peroxidase (G-POD) and superoxide dismutase activities and decreased ascorbate peroxidase (APX) activities were observed in roots treated with 2.0 MS. On the other hand, APX activity was strongly activated along with considerable increase in CAT activity at 0.25 MS treated culture. However, the joint functions of CAT, G-POD and APX at 0.25 MS treated cultures were efficient to eliminate the potential danger of hydrogen peroxide (H(2)O(2)) as evidenced from low H(2)O(2) accumulation and low level of lipid peroxidation.
Abdullahil Baque
Md
M
Research Center for the Development of Advanced Horticultural Technology, Chungbuk National University, Cheong-ju, 361-763, Republic of Korea.
Lee
Eun-Jung
EJ
Paek
Kee-Yoeup
KY
D002374:Catalase / Q000378:metabolism / Q000502:physiology; D003470:Culture Media / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D032066:Morinda / Q000201:enzymology* / Q000254:growth & development* / Q000378:metabolism; D009997:Osmotic Pressure / Q000187:drug effects / Q000502:physiology*; D018384:Oxidative Stress / Q000187:drug effects / Q000502:physiology*; D009195:Peroxidase / Q000378:metabolism / Q000502:physiology; D010650:Phenylalanine Ammonia-Lyase / Q000378:metabolism / Q000502:physiology*; D018517:Plant Roots / Q000201:enzymology* / Q000254:growth & development* / Q000378:metabolism; D012492:Salts / Q000494:pharmacology*; D013482:Superoxide Dismutase / Q000378:metabolism / Q000502:physiology
D003470:Culture Media; D012492:Salts; C121048:guaiacol peroxidase; D002374:Catalase; D009195:Peroxidase; D013482:Superoxide Dismutase; D010650:Phenylalanine Ammonia-Lyase
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