GM cassava plants with unusually big roots were promoted as a super-sizing breakthrough that "could help alleviate hunger in developing countries", but it turned out that plant breeders had already produced cassava roots that were many times larger than the GM ones, at very low cost and without genetic engineering.

When researchers genetically modified cassava plants to produce roots that were "dramatically bigger" than normal, this was press released as a super-sizing breakthrough that "could help alleviate hunger in developing countries".[1]

A team led by Richard Sayre, a professor of plant cellular and molecular biology at Ohio State University, had inserted into the cassava's DNA a bacterial gene that affects starch production. The modified plants' roots were said to be more numerous and up to 2.6 times larger than in normal plants.[2] Sayre leads a multi-institution programme to improve cassava funded by the Bill and Melinda Gates Foundation to the tune of $7.5 million.[3]

But Nagib Nassar, Professor of genetics at the University of Brasilia, responded to an article about the super-sized cassava ("GM cassava has 'super size' roots") by pointing out that he and his colleagues had produced cassava "with roots that are ten times the normal size without resorting to genetic modification." He also noted, "The cost of our research was extremely low. We simply hybridised cassava (Manihot esculenta) with the related wild species Manihot caerulescens. No foreign genes were inserted."[4]

An image of the University of Brasilia researchers' cassava roots, which are around four times the size of the "dramatically bigger" GM super-sized roots, is available online here.[5]


[1] Wagdy Sawahel, "GM cassava has 'super size' roots",, 15 May 2006

[2] "Super-sized cassava may help fight hunger in Africa", Ohio State University, 24 May 2006

[3] "Research Team Receives $7.5 Million To Study Cassava", Ohio State University, 28 June 2005

[4] "Boosting cassava roots the non-GM way", Nagib Nassa, SciDev.Net, 31 May 2006

[5] Photo gallery UNB 120, Gene Conserve website