GM cassava to “double” production of African crops

Claims

The potential of genetic engineering to massively boost the production of cassava – a staple food in Africa – by defeating a devastating virus has been heavily promoted since the 1990s.

In an article published in the LA Times in 1997, Claude M. Fauquet, a French plant virologist, predicted that a food crisis was coming in the years between 2020 and 2030. He said, “We need to improve production. [With some crops], biotech is our only hope.” One of the named crops was cassava.¹⁷ At the time, Fauquet was leading a team at the International Laboratory for Tropical Agricultural Biotechnology, or ILTAB, then based at the Scripps Research Institute, California,² which was working on producing a cassava genetically modified to resist the devastating cassava mosaic virus (CMV), which causes cassava mosaic disease (CMD).

GM, claimed Fauquet, “could double, triple, quadruple production of African crops”. In the case of cassava, Fauquet told the LA Times, the typical yield in Africa was four tons per acre. But “Fauquet maintains that resistance to viruses could boost that tenfold. A mere doubling of production, he added, ‘would represent food independence for the African continent.’” ¹

The first GM cassava plant was developed in 1995 and field testing was originally planned for 1999.¹⁸ By 2000 Fauquet had moved to the Donald Danforth Plant Science Center, ¹⁹ which took over the hosting of his cassava research. The Danforth Center had been launched in 1998 with a $70 million pledge from Monsanto, which also donated the Center’s 40-acre tract of land, near Monsanto’s home town of St Louis, Missouri.⁹

The Danforth Center’s 2004 annual report stated that Fauquet’s team had “developed plants with good [virus] resistance in the greenhouse”, which now needed to be tested in field trials in Africa.²⁰

In late 2005 the St Louis Post-Dispatch reported that although millions were starving in Africa, “The Donald Danforth Plant Science Center says it can feed the continent with cassava, a potato-like crop that a virus has decimated”.³

The Post-Dispatch also reported that although this life-sustaining GM cassava was ready to be field tested, it was not being taken up by African countries in the way the Danforth Center would like: “The center, in Creve Coeur, has leafy, virus resistant plants ready to give away. But no one in Africa is taking them. Field test approvals are stalled in Kenya, Malawi and Nigeria.” The article blamed “the politics of biotechnology in Africa”. According to Lawrence Kent, the Center’s then director of international programmes, these “politics” consisted of “confusion and fear” about GMOs propagated within African countries. According to Kent, “One delay could mean that a million people are going to be hungry for six months… this is serious and we have to fight to make it happen.” ³

In 2005, according to a separate article in the St Louis Post-Dispatch, the Danforth Centre was part of a consortium that received a $7.5 million grant from the Gates Foundation to work on cassava virus resistance as well as biofortification. And in 2006 Monsanto gave the Center $7.5 million more for cassava work.²¹

Results

In July 2006 the Center quietly admitted that its GM cassava varieties had lost their resistance to the virus.⁴

In September 2006 the Danforth Center announced it had received a $15 million gift from the Monsanto Fund, “the philanthropic arm of the Monsanto company”, to fund its Campaign for a Green Future and its efforts “to develop high-yield crops, including virus-resistant cassava, for Africa”.²² An article in the St Louis Post-Dispatch reported, “Danforth Center scientists have engineered a virus-resistant cassava, but have not yet surmounted political hurdles that have kept them from field testing the engineered cassava”.²³

Re-engineering the cassava

In 2011 the Danforth Center received another $11.9 million to research cassava resistant to CMD and to cassava brown streak disease (CBSD). This total included $5.6 million from the Bill & Melinda Gates Foundation, $5.4 million from the Monsanto Fund, and $860,000 from the Howard Buffett Foundation.

Fauquet was quoted as saying, “Our team is confident that the cassava we develop will improve the lives of millions of people, allowing them to not only grow adequate food, but also to increase productivity so they might have enough money left over to educate their children and afford good medical care for malaria and other diseases they face.”¹⁰

In 2016 researchers from the Danforth Center, this time in collaboration with scientists from Uganda, admitted that another GM virus-resistant cassava had lost resistance to CMV. This was due to the effects of the tissue culture process that has to be used with all commonly used genetic engineering methods in cassava. ²⁴

The cassava variety that they were trying to engineer, TME 204, belonged to a naturally CMV-resistant class called CMD2‐type cultivars. However, the GM version lost even this resistance during field cultivation: “The data… show that the CMD2 resistance mechanism was negated in plants of transgenic lines of TME 204 cultivated under field conditions.” ²⁴

Genetic engineer warns against GM gene-edited cassava mutant virus risk

In 2018 plant genetic engineer Devang Mehta, who had been working on developing GM virus-resistant cassava at ETH Zurich under Prof Wilhelm Gruissem, quit GMO research, blaming public “backlash and criticism” of GM technology.²⁵

Two months later, Mehta and his co-researchers published a pre-print paper describing attempts to engineer CMV resistance into cassava by engineering the CRISPR-Cas9 gene-editing tool into the plant together with a guide RNA targeting two viral genes, AC2 and AC3, which code for crucial viral protein functions. The idea was that the engineered cassava would express a gene-altering CRISPR-Cas9, which would knock out these two viral genes. So when the virus infected the cassava, it would be unable to spread in the plant.

However, the engineered CRISPR virus resistance failed and the approach also led to the emergence of a novel mutant virus. The authors wrote, “We have not yet tested the ability of the evolved virus to replicate independently. However, this mutant may also be an intermediate step towards the development of a truly pathogenic novel virus.” They concluded, “Our study highlights the potential for virus escape from this technology. Care should be taken to design CRISPR-Cas9 experiments that minimize the risk of virus escape.” ²⁶

A lesson learned?

In 2022 the Danforth Center announced that its scientists and their collaborators had identified a genetic mutation that confers resistance to CMD, in research part-funded by the Bill & Melinda Gates Foundation. In its press release the Center did not mention any new attempts to use this finding to genetically engineer cassava,²⁷ though the research paper reporting the finding leaves the door open for GM, by calling the genetic mutation “an important genetic resource for resistance breeding and/or genome editing, and elucidating mechanisms of resistance to geminiviruses”.²⁸

While the Danforth Center scientists were still investigating exactly how the resistance works, they stated that non-GM “CMD-resistant cassava varieties exist and are thought to have been originally identified and selected by farmers many decades ago. Many of these varieties are still widely grown and used by breeders as sources of resistance to create new, improved varieties of cassava.” ²⁹

GM cassava engineered for resistance to cassava brown streak disease (CBSD) in field trials

A 2023 review of biotechnology approaches to developing virus-resistant cassava said that RNAi gene disruption technology “represents an important approach to tackling the problem of CMD and CBSD”, but added, “Unfortunately, loss of CMD resistance in these transgenic plants has been reported in the field.” The authors note that rapid evolution of the virus is a challenge to establishing sustained resistance in cassava. However, “Success in obtaining resistance to CBSV using RNAi technology has been achieved. Cassava with resistance to CBSD using RNAi technology has undergone field trials in Uganda and Kenya, and very high levels of resistance were demonstrated.” The review authors recommend using marker assisted selection (a breeding technique that does not result in a GMO) in addition to breeding or genetic engineering to accelerate development of resistant varieties.³⁰

In 2021 Kenya’s National Biosafety Authority greenlighted national performance field trials of a GM cassava engineered using RNAi gene disruption technology for resistance to cassava brown streak disease (CBSD).³¹ In 2023 the National Environment Management Authority (NEMA) issued an environmental impact assessment licence permitting the trials to go ahead. At that time, commercial release was projected to be 5-6 years in the future.⁸ The GM cassava was developed under the Virus Resistant Cassava for Africa Plus (VIRCA Plus) project, a collaborative programme between KALRO, the National Crops Resources Research Institute of Uganda, and the Danforth Center.³²

Conventionally bred virus-resistant cassava

Boy with cassava stems, in a village in the district of Kisarawe, Tanzania, south of Dar es Salaam. Kisarawe is a collection point for cassava roots brought in by local farmers. From there it is trucked to a processing plant in Dar es Salaam. Photo by the late Wally Menne, Timberwatch.org, reproduced with permission.

In 2008 the IITA (International Institute of Tropical Agriculture) announced that it had developed a cassava through conventional breeding which has a high level of resistance to several diseases, including cassava bacterial blight (CBB) and CMD. This cassava was also drought resistant, increasing yield under drought 6- to 10-fold.³³

The FAO (Food and Agriculture Organisation of the United Nations) reported in the same year that farmers were harvesting healthy virus-resistant cassava throughout the Great Lakes region of central Africa, where the cassava mosaic virus was particularly virulent. The FAO said: “By the last planting season, virus-free cassava planting material had been distributed to some 330,000 smallholders in countries struck by the virus – Burundi, the Democratic Republic of Congo, Rwanda and Uganda. The improved crop now benefits a total of some 1.65 million people.” ³⁴

Michael Farrelly, programme officer for the Tanzania-based Alliance for Food Sovereignty in Africa, said in 2018, “A lot of the problem in Africa comes from diseased planting materials. The practical solution is not GM but improved access to quality planting material, coupled with better disease management practices. 

“Cassava is not planted from a seed, but from cuttings, and it doesn’t store well, so commercial seed dealers tend not to sell it. It is generally traded less formally. The Chambezi agricultural station at Bagamoyo in Tanzania is doing a great job of setting up access to clean and disease-resistant planting material, initially from the station and then increasingly produced by local farmers under controlled conditions to ensure quality.” ³⁵

The Food and Agriculture Organisation (FAO) agreed: “Strict quarantine procedures during international exchange of cassava germplasm and the use of resistant/tolerant varieties and virus-free planting material are key for the control of both CMD and CBSD in Africa.” ³⁶

Companies

Research into GM virus-resistant cassava has been led by research institutes, notably the Danforth Center and its research partner ETH Zurich. However, the Danforth Center has strong links with Monsanto (see “Claims”, above). Funding for the research has been dominated by the Monsanto Fund and the Bill & Melinda Gates Foundation (see “Results”, above).

Biotech company Precigen, initially a subsidiary of Intrexon, is owner of an active patent covering genetic engineering methods to inhibit cassava mosaic virus infection.¹¹ In early 2020, the company decided to focus on human healthcare,¹² suggesting it will no longer be involved in GM cassava research.

Patents

A patent search for “cassava mosaic virus resistance” produces several thousand records,³⁷ only some of which are relevant to engineering cassava plants for resistance to the virus. Other records relate to the use of the virus’s promoter for more general genetic engineering purposes and are not relevant to engineering resistance to the disease.

Patent holders, applicants, and inventors on relevant records include the Scripps Research Institute, Claude Fauquet,¹³ North Carolina State University,¹⁴ and the biotech companies Precigen (a subsidiary of Intrexon – Intrexon is now called Precigen; see “Companies”),¹⁵ and Pebble Labs.¹⁶

Author and updated research: Claire Robinson. Original research and review: Jonathan Matthews. Scientific reviewers: Dr Jonathan Latham; Dr Angelika Hilbeck

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1. Groves M (1997). Plant researchers offer bumper crop of humanity. Los Angeles Times, 26 Dec. https://www.latimes.com/archives/la-xpm-1997-dec-26-mn-2352-story.html [↩][↩][↩]
2. LinkedIn (2024). Claude Fauquet. https://www.linkedin.com/in/claude-fauquet-5b7b603b/ [↩][↩]
3. Hand E (2005). Hungry African nations balk at biotech cassava: the politics of biotechnology. St Louis Post-Dispatch, 22 Sept. Archived by newspapers.com: https://www.newspapers.com/image/152005963/?match=1&terms=African%20biotech%20cassava[↩][↩][↩][↩]
4. Donald Danforth Plant Science Center (2006). Danforth Center cassava viral resistance update. 30 Jun, Archived by Wayback Machine 12 Jul 2006. https://web.archive.org/web/20060712221627/http://www.danforthcenter.org/newsmedia/NewsDetail.asp?nid=121[↩][↩]
5. Mehta D et al (2018). CRISPR-Cas9 interference in cassava linked to the evolution of editing- resistant geminiviruses. BioRxiv, 4 May. Preprint doi: https://doi.org/10.1101/314542  The paper was subsequently published in a peer-reviewed journal as: Mehta D et al (2019). Linking CRISPR-Cas9 interference in cassava to the evolution of editing-resistant geminiviruses. Genome Biol. 20(1):80. doi: 10.1186/s13059-019-1678-3. https://pubmed.ncbi.nlm.nih.gov/31018865/ ; Devang Mehta on Twitter/X @drdevangm (2018). 5 May. https://twitter.com/drdevangm/status/992765598475210752 [↩]
6. IITA (2008). Farmers get better yields from new drought-tolerant cassava. 3 Nov. Archived by Wayback Machine 22 Jan 2010. https://web.archive.org/web/20100122004438/http://www.iita.org/cms/details/print-article.aspx?articleid=1897&zoneid=342 ; FAO (2008). Cassava’s comeback: On the plate of over 1,5 million people in Africa. 13 Nov. Archived by Wayback Machine 5 Mar 2009. https://web.archive.org/web/20090305073040/http://www.fao.org/news/story/en/item/8490/icode/ ; Farrelly M (2018). Personal communication with Claire Robinson of GMWatch. Quoted in: Robinson C (2018). Is the public to blame for collapse of the GMO venture? – Part 2. GMWatch, 8 May. https://gmwatch.org/en/106-news/latest-news/18266 ; Food and Agriculture Organization (FAO) (2013). Managing cassava virus diseases in Africa: The Regional Cassava Initiative. http://www.fao.org/fileadmin/user_upload/emergencies/docs/RCI%20Cassava%20brochure_ENG_FINAL.pdf ;  Hilbeck A (2018). Personal communication with Claire Robinson of GMWatch. Quoted in: Robinson C (2018). Is the public to blame for collapse of the GMO venture? – Part 2. GMWatch, 8 May. https://gmwatch.org/en/106-news/latest-news/18266 [↩]
7. Kenya National Biosafety Authority (2021). Press release: NBA board approves environmental release application for GM cassava. 22 Jun. https://www.biosafetykenya.go.ke/images/NBA-Board-Approves-application-for-Genetically-Modified-Cassava-FINAL.pdf [↩]
8. Food Safety Africa (2023). NEMA permits National Performance Trials on GMO cassava, paving way for commercialization. 24 Feb. https://www.foodsafetyafrica.net/nema-permits-national-performance-trials-on-gmo-cassava-paving-way-for-commercialization/[↩][↩]
9. Sharpe VA, Gurian-Sherman D (2003). Competing interests. Nature Biotechnology 21(1131). https://www.nature.com/articles/nbt1003-1131a[↩][↩]
10. Philanthropy News Digest (2011). Danforth Center receives $11.9 million to develop virus resistant crops for Africa. 11 Sept. https://philanthropynewsdigest.org/news/danforth-center-receives-11.9-million-to-develop-virus-resistant-crops-for-africa ; Donald Danforth Plant Science Center (2011). Danforth Center Collaborative Research Program receives funding to improve crop yield in Africa. Eurekalert, 6 Sept. https://www.eurekalert.org/news-releases/772958[↩][↩]
11. Lens.org https://www.lens.org/lens/patent/002-714-085-435-342/fulltext Search performed 22 April 2024.[↩][↩]
12. Keown A (2020). Intrexon begins 2020 with a new CEO and name change. BioSpace, 2 Jan. https://www.biospace.com/article/intrexon-changes-name-to-precigen-taps-new-ceo/[↩][↩]
13. Lens.org https://www.lens.org/lens/patent/194-589-565-021-918/frontpage?l=en ; https://www.lens.org/lens/patent/159-133-552-330-792/fulltext?l=en  Search performed 16 April 2024.[↩][↩]
14. Lens.org https://www.lens.org/lens/patent/111-494-090-553-271/frontpage?l=en  Search performed 16 April 2024.[↩][↩]
15. Lens.org https://www.lens.org/lens/patent/002-714-085-435-342/frontpage?l=en  Search performed 16 April 2024.[↩][↩]
16. Lens.org https://www.lens.org/lens/patent/171-869-891-872-103/frontpage?l=en  Search performed 16 April 2024.[↩][↩]
17. Groves M (1997). Plant researchers offer bumper crop of humanity. Los Angeles Times, 26 Dec. https://www.latimes.com/archives/la-xpm-1997-dec-26-mn-2352-story.html  Note that ILTAB, which hosted Fauquet’s cassava research at this time, ceased to exist in 2012 – see UIA Global Civil Society Database (2022). International Laboratory for Tropical Agricultural Biotechnology (ILTAB). https://uia.org/s/or/en/1100064316 [↩]
18. Groves M (1997). Plant researchers offer bumper crop of humanity. Los Angeles Times, 26 Dec. https://www.latimes.com/archives/la-xpm-1997-dec-26-mn-2352-story.html  [↩]
19. LinkedIn (2024). Claude Fauquet. https://www.linkedin.com/in/claude-fauquet-5b7b603b/[↩]
20. Donald Danforth Plant Science Center Annual Report 2004. Archived by Wayback Machine 3 Mar 2006. https://web.archive.org/web/20060303181458/http://www.danforthcenter.org/media/scireport/annual_report_2004.pdf [↩]
21. Hand E (2006). St Louis team fights crop killer in Africa. St Louis Post-Dispatch, 9 Dec. Archived by GMWatch, 9 Dec: https://gmwatch.org/en/news/archive/2006/5580 [↩]
22. Philanthropy News Digest (2006). Danforth Plant Science Center receives $15 million. 8 Sept. https://philanthropynewsdigest.org/news/danforth-plant-science-center-receives-15-million [↩]
23. Hand E (2006). Monsanto gives $15 million to Danforth Plant Science Center. St Louis Post-Dispatch, 5 Sept. Archived by SayNotoGMOs.org, https://www.saynotogmos.org/ud2006/usept06a.php [↩]
24. Beyene G et al (2016). Loss of CMD2-mediated resistance to cassava mosaic disease in plants regenerated through somatic embryogenesis. Mol Plant Pathol. 17(7):1095-1110. doi:10.1111/mpp.12353. https://pubmed.ncbi.nlm.nih.gov/26662210/[↩][↩]
25. Mehta D (2018). Why I’m quitting GMO research. Massive Science, 27 Mar. https://massivesci.com/articles/gmo-gm-plants-safe/[↩]
26. Mehta D et al (2018). CRISPR-Cas9 interference in cassava linked to the evolution of editing- resistant geminiviruses. BioRxiv, 4 May. Preprint doi: https://doi.org/10.1101/314542  The paper was subsequently published in a peer-reviewed journal as: Mehta D et al (2019). Linking CRISPR-Cas9 interference in cassava to the evolution of editing-resistant geminiviruses. Genome Biol. 20(1):80. doi: 10.1186/s13059-019-1678-3. https://pubmed.ncbi.nlm.nih.gov/31018865/[↩]
27. Danforth Center (2022). New research reveals mutation responsible for disease resistance in cassava. 13 Jun. https://www.danforthcenter.org/news/new-research-reveals-mutation-responsible-for-disease-resistance-in-cassava/[↩]
28. Lim Y-W et al (2022). Mutations in DNA polymerase δ subunit 1 co-segregate with CMD2-type resistance to Cassava Mosaic Geminiviruses. Nature Communications 13:3933. https://doi.org/10.1038/s41467-022-31414-0 [↩]
29. Danforth Center (2022). New research reveals mutation responsible for disease resistance in cassava. 13 Jun. https://www.danforthcenter.org/news/new-research-reveals-mutation-responsible-for-disease-resistance-in-cassava/[↩]
30. Ntui VO et al (2024). Cassava molecular genetics and genomics for enhanced resistance to diseases and pests. Molecular Plant Pathology 25(1). Jan. e13402. https://doi.org/10.1111/mpp.13402[↩]
31. Kenya National Biosafety Authority (2021). Press release: NBA board approves environmental release application for GM cassava. 22 Jun. https://www.biosafetykenya.go.ke/images/NBA-Board-Approves-application-for-Genetically-Modified-Cassava-FINAL.pdf [↩]
32. KALRO (2021). Kenya National Biosafety Authority approves genetically modified cassava. ISAAA, 23 Jun. https://www.isaaa.org/blog/entry/default.asp?BlogDate=6/23/2021[↩]
33. IITA (2008). Farmers get better yields from new drought-tolerant cassava. 3 Nov. Archived by Wayback Machine 22 Jan 2010. https://web.archive.org/web/20100122004438/http://www.iita.org/cms/details/print-article.aspx?articleid=1897&zoneid=342[↩]
34. FAO (2008). Cassava’s comeback: On the plate of over 1,5 million people in Africa. 13 Nov. Archived by Wayback Machine 5 Mar 2009. https://web.archive.org/web/20090305073040/http://www.fao.org/news/story/en/item/8490/icode/ [↩]
35. Farrelly M (2018). Personal communication with Claire Robinson of GMWatch. Quoted in: Robinson C (2018). Is the public to blame for collapse of the GMO venture? – Part 2. GMWatch, 8 May. https://gmwatch.org/en/106-news/latest-news/18266[↩]
36. Food and Agriculture Organization (FAO) (2013). Managing cassava virus diseases in Africa: The Regional Cassava Initiative. http://www.fao.org/fileadmin/user_upload/emergencies/docs/RCI%20Cassava%20brochure_ENG_FINAL.pdf[↩]
37. Lens.org https://www.lens.org/lens/search/patent/list?q=CMV%20resistance%20cassava Search performed 16 April 2024.[↩]