Ketocarotenoid formation in transgenic potato

Area of Science:

• Plant Biotechnology
• Metabolic Engineering
• Carotenoid Biosynthesis

Background:

• Ketocarotenoids, such as astaxanthin, are commercially valuable compounds.
• Genetic engineering offers a pathway to enhance the production of these compounds in plants.
• Potato (Solanum tuberosum) is a staple crop with potential for metabolic engineering.

Purpose of the Study:

• To engineer potato plants for the production of ketocarotenoids, specifically astaxanthin.
• To investigate the feasibility of co-expressing genes involved in carotenoid modification.
• To assess the accumulation and impact of ketocarotenoids in transgenic potato.

Main Methods:

• Development of a transgenic potato line with inactivated zeaxanthin epoxidase to accumulate zeaxanthin.
• Co-transformation with the cyanobacterial `crtO` gene encoding beta-carotene ketolase under a constitutive promoter.
• Analysis of ketocarotenoid profiles in leaves and tubers using biochemical assays.
• Assessment of photosynthetic efficiency via variable fluorescence measurements.

Main Results:

• Transgenic potato lines successfully expressed the `crtO` gene, leading to ketocarotenoid accumulation.
• Echinenone, 3'-hydroxyechinenone, and 4-ketozeaxanthin accumulated in leaves.
• Astaxanthin, along with 3'-hydroxyechinenone and 4-ketozeaxanthin, accumulated in tubers.
• Ketocarotenoids constituted approximately 10-12% of total carotenoids in leaves and tubers.
• No negative effects on photosynthesis were observed in the presence of ketocarotenoids.

Conclusions:

• Genetic engineering of potato is effective for producing commercially important ketocarotenoids, including astaxanthin.
• Co-expression of specific genes enables the biosynthesis of desired ketocarotenoid profiles in different plant tissues.
• The accumulation of ketocarotenoids in potato does not impair photosynthetic function.