The ICAR-Central Tuber Crops Research Institute (CTCRI) in Thiruvananthapuram has embarked on a ₹4 crore research project for developing tapioca varieties with waxy or high-amylose starches that are useful in industry with the help of CRISPR-Cas9 genome editing technology.
Waxy starch has uses in food products, adhesives, textile and pharmaceuticals, the CTCRI said.
Tapioca (cassava) varieties available in India have limited scope in industry owing to their starch composition, which, on an average, is 20% amylose and 80% amylopectin.
“If we can develop varieties wherein the starch composition is altered as 0-10% amylose and 90-100% amylopectin, it becomes waxy starch. When the starch composition is altered as 70% amylose and 30% amylopectin, it becomes high amylose starch. High amylose starch has applications in the functional food industry, has low glycemic index and also acts as a gut protectant prebiotic, feeding the gut bacteria, thereby improving colon health,” the CTCRI said. It is also used in low-calorie food products and in biofilms, coatings, textiles and paper.
This is where CRISPR-Cas9 comes in.
The technology hinges on the inherent ability of DNA to repair itself after a double-stranded break in it. The gene is altered during the repair, with loss or gain of function. CTCRI plans to release tapioca varieties with waxy starch by silencing granule-bound starch synthase gene (GBSS) and high amylose starch by silencing starch branching enzyme (sbe) I and IIb, according to Krishna Radhika N., senior scientist and component principal investigator of the project.
The development of waxy and resistant starch tapioca varieties will serve to address the lack of industry-suited tapioca varieties in India, CTCRI director G. Byju said. This shortage had resulted in a need to import modified tapioca starch into the country.
