PROFILE

Defeating late blight disease of potato
in sub-Saharan Africa
Three academic experts, including Richard E. Goodman from the Food Allergy Research andResource Program, shed light on defeating late blight disease of potato in sub-Saharan Africa,
starting with a brief introduction to the crop in question

Potatoes have been grown in$150/tonne of potatoes, the annual

Organisation (NARO) with CIP collab-

South America for over 7,000

cost of LBD is estimated to be $500 tooration in Uganda since 2015 under$800 million for the 14 potato producing

full regulatory compliance by thecountries in SSA.

National Biosafety Committee (NBC).

years. Spanish explorers broughtthem to Europe in the 16th century
where it took almost two centuries tobecome a widely grown staple food.

Up to 15 transgenic events were

Breeding for resistance tolate blight in potato

tested from two varieties at the main

Breeding for resistance has trans-

western Uganda. Remarkably, all 3R

Africa in the 18th century. Now inferred resistant R genes from wild

potato transgenic events grew with-

Sub-Saharan Africa (SSA), potato ispotato relatives to food grade pota-out being affected by LBD without

cultivated on 1.7 million hectares in 14

toes. However, since potato is afungicides whereas the non-trans-countries at mid to high elevations. It

tetraploid and highly heterozygous, it

genic varieties were devastated. Twois grown by about 7 million farmers

is virtually impossible to combine

transgenic events from the prominent

for food and income. It brings a higher

multiple R genes from wild relatives by

Ugandan variety Victoria were grownamount of carbohydrate, and protein

traditional breeding while keeping allin three locations and resulted in fullper ha compared to cereals and is aqualities of an elite variety. It took 45

control of the disease at all locations.

good source of vitamin C, B12, potas-years to transfer a single resistance R

The 3R Victoria transgenic events havesium and fibres.

gene from Solanum bulbocastanum

been grown successfully without

into a modern variety by conventional

fungicides in more than a dozen field

Impact of late blight disease(LBD) on potato production

breeding.

trials over the last five years.

Phytophthora infestans is a water

Genetic transformation techniques in

3R potatoes have been developed andmould (Oomycetes) that infects pota-

the last 30 years provide a more direct

field-tested over the last decade in atoes and tomatoes. It caused the Irish

transfer mechanism into existing elite

wide diversity of environments in The

potato famine that killed more thanvarieties lacking resistance to LBD.

Netherlands, Belgium, Ireland, United

one million people from 1845 to 1849

The 3R potato was developed by theKingdom, Sweden, U.S., Indonesia

and led another two million to emi-International Potato Center (CIP) byand Bangladesh. At all locations, thegrate. Infection of potatoes causes

transferring three R genes chosentransgenic potatoes were grown

wilting of the leaves and eventuallyfor their ability to recognise a broad

without fungicides and yielded very

the whole plant while tubers rot after

spectrum of strains of P. infestans into

well without any negative impact onstorage. The LBD remains the main

farmers’ preferred varieties lacking

the environment.

threat to potato production globally

resistance to LBD.

Today, it ranks third after rice andwheat. The potato was introduced inwith a 15-30% production reduction.

potato research institute in South-The stability of resistance to LBD isUsing an average cost of fungicide

Confined field trials were conducted

expected to be long lasting because

per ha of $100 and average price ofby the National Agriculture Research

additional

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resistancegenes

arePROFILE

Devastation by late blight disease - Confined field trial at Kachwekano research station in 2019 inUganda under natural infestation by late blight with plots planted with either 3R Victoria or Victoria.

available (Vleeshouwers et al., 2011).

fragments of wild Solanum bulbocas-toxins using proven methodologies

The rotation of transgenic varieties

tanum, and Solanum venturii, the sameand results indicate no need for addi-with different sets of resistance genes

as those breeders could introduce

tional testing (Goodman et al., 2008).

will ensure long-term resistance to LBD.

by crossing (Ghislain et al., 2019). Thegenes

areThe nptII selectable marker gene wasSafety of 3R Victoria tohuman healthinducible locally by the presence ofencoding

introduced with the 3R-gene stack andthe pathogen and the R proteins are

as in other released transgenic crops,

The safety of many R genes has been

expressed in potato tubers at concen-

the concentration of NPTII protein isdemonstrated through the consump-

trations

levelsvery low. It has also a history of safetion of common natural potato(Habig et al., 2018). The R proteins areuse with 122 transgenic varieties

varieties although not in a systematic

not toxins that directly kill pathogens.

approved for cultivation, food, or feedway. They belong to a large gene

They cause a localised reaction inuses (EFSA 2009; Nicolai et al. 2014;

family of at least 3,000 members inpotato, causing the death of potato

http://www.isaaa.org/gmapproval-each potato variety to provide resis-

cells, depriving the pathogen ofdatabase/default.asp, accessed July 7,

tance and immunity against a wide

nutrients. Potential allergenicity and2019). Tuber samples from the trans-

range of pests and pathogens (Jupe ettoxicity of these proteins were evalu-

genic potato and the non-transgenical., 2013). The three R genes in Victoria

ated by comparing their amino acidvariety (parental line) were analysed

were selected from unmodified DNA

sequences to known allergens andfor the essential five components

belowRproteinsdetectable

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Yield gain of 3R Victoria - Potato harvest from the transgenic potato 3R Victoria (left) and the conventional
potato Victoria (right) grown without fungicide at Kachwekano research station in 2019 in Uganda.

recommended by the OECD. Moisture,years in Uganda have confirmed thecopper-based fungicides, have somesugars (especially reducing sugars),absence of impacts on non-target

negative impacts on the environment,

vitamin C, ash, protein, and glycoalka-organisms (NTO). We commonlyin particular, the soil eco-systems. The

loid contents were mostly identicalobserved above ground organisms

3R Victoria potato offers advantages

and all values were within the range

such as arthropods, with no obvious

of no environmental disturbancereported in the literature for potato

reduction in abundance. There were no

while lowered energy and resource

tubers (OECD 2015; AFSI 2019).

statisticallycosts needed for LBD control.

significant

differences

between plots with the 3R Victoria andEnvironmental safety oftransgenic potatoes withLBD resistancethose with Victoria and those with Victoria

In SSA, the cost of LBD is severe wherefor whiteflies, leaf miner flies, beetles,

farms are commonly only one quarter

aphids, red ants, and spiders whichof a hectare and losses of 30-60% are

There is no plausible risk hypothesis

were the only NTO observed in thecommon. In Uganda, we estimatedfor environmental damage from thefields. Though still limited, our observa-

the benefits of adoption of the 3R

3R Victoria event. Field studies oftions confirm that the 3R Victoria does

Victoria by the small-farm holders toother transgenic potatoes expressing

not pose an environmental hazard.

increase their profit by at least 40%.

R proteins have not shown differencesin arthropod abundance compared
to conventional potato lines in two
locations over two seasons (van derAlso, the 3R potato is beneficial in

The ethics of approving theLBD resistant potato

Farmers currently use fungicides toterms of reduction in fungicide use
and carbon emissions (Haverkort etal., 2008; Kessel et al., 2018).

Voet et al., 2019). Similar field studies

control LBD and partially resistantconducted with the 3R Victoria potato

potato varieties with limited success.

The 3R Victoria potato is, therefore, aby the NARO and CIP over the last fiveFungicides, including organic certified

huge value gain for the sustainability

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PROFILE
Allergenicity assessment of genetically modified crops - what makes
sense? Nat Biotech 26(1):73-81.
Habig, J. W., Rowland, A., Pence, M. G., & Zhong, C. X. (2018).
Food safety evaluation for R-proteins introduced by biotechnology:
a case study of VNT1 in late blight protected potatoes. Regulatory
Toxicology and Pharmacology, 95, 66-74.
Haverkort, A. J., Boonekamp, P. M., Hutten, R., Jacobsen, E., et al.
(2008). Societal costs of late blight in potato and prospects ofdurable resistance through cisgenic modification. Potato research,
51(1), 47-57.

Marc Ghislain

Alex Barekye

technology fees. There will, however,be a need to continue developing
and maintaining high-quality potato
varieties to maintain resistance tonew strains of Phytophthora infestans.
If we do so, we will eventually defeat
LBD and its dramatic consequenceson the fragile economy of small-farmholders in SSA.

Jupe, F., Witek, K., Verweij, W., Śliwka, J., et al. (2013). Resistancegene enrichment sequencing (RenSeq) enables reannotation of theNB-LRR gene family from sequenced plant genomes and rapid
mapping of resistance loci in segregating populations. The Plant
Journal, 76(3), 530-544.
Kessel, G. J., Mullins, E., Evenhuis, A., Stellingwerf, J., et al. (2018).
Development and validation of IPM strategies for the cultivation ofcisgenically modified late blight resistant potato. European Journalof Agronomy, 96, 146-155.
Nicolia, A., Manzo, A., Veronesi, F., & Rosellini, D. (2014). An
overview of the last 10 years of genetically engineered crop safety
research. Critical reviews in biotechnology, 34(1), 77-88.
OECD (2015), “Potato (Solanum tuberosum ssp. tuberosum)”, inSafety Assessment of Foods and Feeds Derived from TransgenicAuthors

Crops, Volume 1, OECD Publishing, Paris. DOI: http://dx.doi.org/Marc Ghislain1 (M.Ghislain@cgiar.org)

10.1787/9789264180147-7-en

Rick Goodman2 (rgoodman2@unl.edu)
Alex Barekye3 (alexbarekye@yahoo.com)

of potato production, food security,

Affiliation:

income generation, and environmen-1tal protection. Wide-spread adoptionof 3R potato varieties will contribute2

to both Africa and the U.S. in terms of
Sustainable Development and Climate

International Potato Centre, P.O. Box 25171,
Nairobi 00603, Kenya

van der Voet, H., Goedhart, P. W., Lazebnik, J., Kessel, G. J., et al.
(2019). Equivalence analysis to support environmental safetyassessment: Using nontarget organism count data from fieldtrials with cisgenically modified potato. Ecology and evolution, 9(5),2863-2882.
Vleeshouwers, V.G., Finkers, R., Budding, D., Visser, M., Jacobs,M.M., van Berloo, R., Pel, M., Champouret, N., Bakker, E., Krenek,
P. and Rietman, H., 2011. SolRgene: an online database to explore
disease resistance genes in tuber-bearing Solanum species. BMC
plant biology, 11(1), p.116.

Food Allergy Research and Resource Program,
University of Nebraska, Lincoln, NE U.S.

3

Kachwekano Zonal Agricultural Research andChange goals. Delaying its adoption

Development Institute, P. O. Box 421, Kabale,by potato farmers will cause theUganda

continued use of pesticides andproduction losses affecting the mostvulnerable farmers and consumers.

Commercialisation of 3R
potatoes once approved

The 3R Victoria potato is currently infield tests for regulatory approvals in
SSA. Once approved, good stewardship practices are needed to ensure
quality seeds are available for farmers.
Since the 3R potato was produced

References
AFSI (Agriculture and Food Systems Institute), 2019. Crop
Composition Database, Version 6, www.cropcomposition.org.
EFSA (European Food Safety Authority) (2009). Consolidated
presentation of the joint Scientific Opinion of the GMO and BIOHAZ
Panels on the “Use of Antibiotic Resistance Genes as Marker Genesin Genetically Modified Plants” EFSA Journal, 1108: 1–8.
Ghislain M, Byarugaba A, Magembe E, Njoroge A, et al. (2019).
Stacking three late blight resistance genes from wild species directly
into African highland potato varieties confers complete fieldresistance to local blight races. Plant Biotech J 17:1119–1129,

entirely by public research organisa-

doi:10.1111/pbi.13042.

tions, there is no need for payment ofGoodman RE, Vieths S, Sampson HA, Hill D, et al. (2008).

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Richard E. Goodman, PhD, FAAAAI
Research Professor, Food Science& Technology
Food Allergy Research and Resource Program
Rgoodman2@un.edu
Mobile +1(402) 417 5549
www.allergenonline.org