A bacterial mannitol-1-phosphate dehydrogenase (mtlD) gene driven by the constitutive cauliflower mosaic virus (CaMV) 35S promoter was transferred into tomato plants using an Agrobacterium tumefaciens-mediated transformation protocol in an attempt to improve abiotic stress tolerance in the transformed plants. Transgene integration was confirmed by PCR analysis and Southern blot analysis, and transgene expression was confirmed by reverse transcription (RT)-PCR and direct mtlD (EC 1.1.1.17) activity. Upon exposure to low temperature stress (4°C) in a cold chamber, transgenic plants survived up to 48 h, while nontransformed plants were unable to survive and gradually died. Transgenic plants subjected to the chilling stress showed a significant decrease in electrolyte leakage and increased lipid peroxidation, as assessed by measuring malondialdehyde (MDA) content. Under the cold condition, transgenic plants also showed a significant increase in the activities of antioxidant enzymes (superoxide dismutase and catalase) and in relative water content (RWC) in comparison to non-transformed plants. Drought (polyethylene glycol in medium) and salinity (sodium chloride in medium) tolerance tests revealed that transgenic lines exhibited a higher tolerance for abiotic stresses than non-transformed plants. These findings indicate that the introduction of a bacterial mtlD gene into tomato conferred tolerance to abiotic stresses to the transformed tomato plants.
Background:Free radicals or highly reactive oxygen species are capable of inducing oxidative damage to human body. Antioxidants are the compounds which terminate the attack of reactive species and reduce the risk of diseases. Both Baccopa monnieri and Centella asiatica are used in treatment of brain disorders in humans and have almost similar effects.Objective:The study was conducted to determine the antioxidant properties of two well-known memory enhancer medicinal plants Baccopa monnieri and Centella asiatica.Results:The antioxidant activity of these two medicinal plants was evaluated by measuring reducing ability, free radical scavenging activity by DPPH and hydrogen peroxide methods. The antioxidants compounds like ascorbic acid, total phenols and tannins were also evaluated in these plants. Baccopa monnieri and Centella asiatica exhibited significant differences (P<0.05) in their antioxidant values. The methanolic extract of whole leaf powder of Baccopa monnieri exhibited significantly higher antioxidant activity than the Centella asiatica. The antioxidant components viz. ascorbic acid, total phenols and tannins were also found in a higher concentration in Baccopa monnieri as compared to Centella asiatica.Conclusion:It can be concluded from the study that regular use of Baccopa monnieri as a supplement could be more helpful compared to Centella asiatica in treatment of neurological disorders caused by free radical damage.
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