Abstract
Monodehydroascorbate reductase (MDHAR, EC 1.6.5.4) is a key enzyme of the ascorbate (AsA)-glutathione cycle that maintains reduced pools of AsA and serves as an important antioxidative enzyme. Previously, we have cloned MDHAR cDNA from acerola ( Malpighia glabra), a plant that accumulates abundant amount of AsA. In this study, MDHAR cDNA from acerola was introduced into tobacco plants using an Agrobacterium-mediated gene delivery system. Transgenic tobacco plants accumulated greater amounts of AsA and showed higher MDHAR activity than the control plants. Lipid peroxidation and chlorophyll degradation, which were stimulated in control plants, were restrained in transgenic plants subjected to salt stress. These results indicate that overexpression of acerola MDHAR imparts greater tolerance to salt stress.
Highlights
Unable to move from their natural environment, higher plants undergo many unfavorable conditions such as drought, salinity, and extreme temperatures
We used DNA blot analysis with Malpighia glabra MDHAR (MgMDHAR) cDNA as a probe to verify the presence of MgMDHAR and estimate the copy-number of the transgene integrated into the isolated genomic DNA of the controls and transgenic plants
RNA blot analysis indicated that MgMDHAR mRNA was expressed in the transgenic plants, but not the control plants (Fig. 1E)
Summary
Unable to move from their natural environment, higher plants undergo many unfavorable conditions such as drought, salinity, and extreme temperatures. Salinity is a major environmental factor leading to the deterioration of agricultural land and reduction in crop productivity (Vaidyanathan et al, 2003). About one-third of the world’s cultivated land is estimated to be affected by salinity (Kaya et al, 2002). Salinity causes diverse adverse effects such as the production of reactive oxygen species (ROS). These interact with a number of cellular molecules and metabolites, thereby leading to various destructive processes and cellular damage (Ashraf, 2009). ROS can seriously damage chlorophyll, proteins, membrane lipids, and nucleic acids (Alscher et al, 1997)
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