Ascorbic acid contents in transgenic potato plants overexpressing two dehydroascorbate reductase genes

Area of Science:

• Plant Biotechnology
• Nutritional Biochemistry
• Horticultural Science

Background:

• Ascorbic acid (AsA, vitamin C) is crucial for human health and crop quality.
• Dehydroascorbate reductase (DHAR) enzymes are vital for maintaining cellular AsA levels through redox recycling.
• Potato (Solanum tuberosum) is a globally important crop where AsA content significantly impacts nutritional value.

Purpose of the Study:

• To investigate the potential of enhancing AsA content in potato.
• To characterize and overexpress cytosolic and chloroplastic DHAR isoforms in potato.
• To evaluate the impact of DHAR overexpression on AsA levels in different potato tissues.

Main Methods:

• Isolation and characterization of potato DHAR cDNA sequences.
• Development of transgenic potato lines overexpressing cytosolic and chloroplastic DHAR genes.
• Confirmation of transgene integration using PCR and real-time RT-PCR.
• Enzyme activity assays for DHAR and quantification of AsA content in leaves and tubers.

Main Results:

• Overexpression of cytosolic DHAR significantly increased DHAR activity and AsA content in both potato leaves and tubers.
• Overexpression of chloroplastic DHAR increased DHAR activity and AsA content in leaves but not in tubers.
• Transgene integration and expression were confirmed in the developed transgenic lines.

Conclusions:

• Ascorbic acid content in potato can be effectively elevated by enhancing its recycling pathway via DHAR overexpression.
• Cytosolic DHAR plays a more significant role than chloroplastic DHAR in increasing AsA content specifically in potato tubers.
• Targeting cytosolic DHAR presents a promising strategy for improving the nutritional quality of potato through increased vitamin C levels.