Tuber-specific cphA expression to enhance cyanophycin production in potatoes

Area of Science:

• Plant Biotechnology
• Biopolymer Production
• Metabolic Engineering

Background:

• Developing biodegradable polymers from transgenic plants is crucial for replacing petrochemicals.
• Plant metabolic engineering often faces challenges with reduced plant fitness and abnormal phenotypes.

Purpose of the Study:

• To engineer potato tubers for enhanced biodegradable polymer (cyanophycin) production.
• To mitigate phenotypic abnormalities by restricting polymer accumulation to tubers.
• To compare cytosolic versus plastidic expression of cyanophycin synthetase in potato tubers.

Main Methods:

• Utilized the cyanophycin synthetase gene (cphA(Te)) from Thermosynechococcus elongatus BP-1.
• Employed tuber-specific class 1 promoter (B33) for controlled gene expression.
• Investigated both tuber-specific cytosolic (pB33-cphA(Te)) and plastidic (pB33-PsbY-cphA(Te)) expression strategies.

Main Results:

• Significant cyanophycin accumulation was achieved exclusively in potato tubers under both expression strategies.
• Plastidic expression (pB33-PsbY-cphA(Te)) yielded up to 7.5% cyanophycin of dry weight with normal tuber size.
• Cytosolic expression (pB33-cphA(Te)) resulted in lower yields (2.3%) and smaller, deformed tubers.
• Plastidic expression showed stable cyanophycin content during storage, despite increased stress symptoms.

Conclusions:

• Tuber-specific expression of cyanophycin synthetase is effective for biodegradable polymer production in potatoes.
• Plastidic targeting enhances polymer yield and avoids detrimental effects on tuber morphology.
• This approach holds potential for sustainable biopolymer production in plants.