A natural variation is found to enhance provitamin A in cassava roots employing transgenic or conventional methods.
Professor Peter Beyer from Freiberg University in Germany, together with researchers at the International Center for Tropical Agriculture (CIAT) in Colombia studied a naturally arising variant of cassava with yellow roots in order to understand the synthesis of provitamin A carotenoids, dietary precursors of vitamin A.
The scientists compared different cassava cultivars with white, cream, or yellow roots - more yellow corresponding to more carotenoids - in order to determine the underlying causes of the higher carotenoid levels found in the rare yellow-rooted cassava cultivar.
They tracked the difference down to a single amino acid change in the enzyme phytoene synthase and showed that the analogous change in phytoene synthases from other species also results in increased carotenoid synthesis.
Furthermore, they were able to turn a white-rooted cassava cultivar into a yellow-rooted plant that accumulates beta-carotene (provitamin A) using a transgenic approach that increased the enzyme phytoene synthase in the root.
"It paves the way for using transgenic or conventional breeding methods to generate commercial cassava cultivars containing high levels of provitamin A carotenoids, by the exchange of a single amino acid already present in cassava" said Beyer.
The article is published in The Plant Cell.