Andrew Kiggundu Abstract Late blight (LB) of potato, caused by Phytophthora infestans, is one of the most devastating diseases of potato (Solanum tuberosum L.) in Africa and in many parts of the world. Conventional cross-breeding to develop resistance has met with challenges of length of breeding time and durability of resistance in the hybrids developed. Three resistance genes (RB, Rpi-blb2, and Rpi-vnt1.1) previously cloned from two wild potatoes, S. bulbocastanum and S. venturii, and the availability of a potato transformation system allowed us to introduce all three genes into cultivated varieties in order to develop durable resistance. The genes were introduced into two cultivated potato varieties ‘Desiree’ and ‘Victoria’. The genetically modified (GM) potatoes generated were field-evaluated in Uganda at the Kachwekano Zonal Agricultural Research and Development Institute in Kabale. Twelve transgenic events of the variety ‘Desiree’ and one of the variety ‘Victoria’ were tested in three replications, each consisting of randomised complete block design of plots of 15 plants each. The results indicate that all 13 transgenic events are completely resistant to LB disease. These GM potatoes, if incorporated into the seed potato system for uptake by farmers in Africa and elsewhere, offer a great opportunity for durable, cost-effective, and environmentally friendly solution to the management of LB disease in potato. Consequently, farmers could discontinue their current practice of spraying toxic chemicals to control the disease. The next steps for further development of these lines into commercial varieties for Africa and the associated deregulation challenges are discussed

1. Towards Zero-
Fungicide Genetically
Modified Potatoes for
Africa
Andrew Kiggundu et. al.

2. Mechanisms of Plant Defense
• Structural resistance; cuticle, wax, cell wall
strengthening
• Hypersensitive response; cell death
• Production of reactive oxygen species
• Production of microbial products (enzymes,
phenolics toxins etc)
• Defense signal transduction

3. Gene to gene resistance in potato
Pathogen (Avr genes)
Elicitors – Avirulence molecules
Recognized by R-proteins of R-genes in Plants
Signaling throughout the plants
Resistance response
• This integration is highly variety/cultivar/pathogen race specific
• One R-gene may respond to more than one pathogen Avr
• More than one R-gene may respond to one pathogen Avr

4. Solanum bulbocastanum
Southern Illinois University (http://www.phytoimages.siu.edu/)
• R genes from wild relatives:
• RB (Rpi-blb1)
• Rpi-blb2
• Dr. Jiming Jiang
• University of Wisconsin–
Madison

5. Centre for Genetic Resources, The Netherlands (CGN), Potato collection
Solanum venturii
• R genes from wild relatives:
• Rpi-vnt1.1
• Prof. Jonathan Jones
Sainsbury Lab (UK)

6. pC IP 68
20413 bp
nptII
nptIII
RB IS1
nos terminator
nos promoter
oriV
ColE1
RB
LB
pC IP 95
14683 bp
KanR
hptII
CDS
Intron
Intron
RB
STA
bom site
LB
p35S
pVS1-REP
pBR322 ori
t35S
Rpi-blb2
pC IP93
13058 bp
Kan
nptII
Rpi-vnt1.1
pVS1 sta
bom
LB
RB
35S term
Promoter Rpi-vnt1.1
35 S
Promoter P 2
pVS1 rep
Ori
Terminator Rpi-vnt1.1
Cloning the genes and vectors…
3R gene stack [RB, Rpi-blb2, Rpi-vnt1.1] by
Agrobacterium-mediated transformation and
selectable marker gene nptII-KanR

7. Genetic transformation
Agrobacterium-mediated transformation of potato

8. Popular Varieties in East Africa
TigoniVictoria/Asante Shangi
Desiree
(POC)
• 74% of farmers
• Short Dormancy
• 3-4 Mon Maturity
• 30-40/ha Yield
• Mashing, Boiling,
Roasting & Chips
• Short cooking time
• Tasty
• 20.7% of Farmers
• Short Dormancy
• 3 Mon Maturity
• 35-45/ha Yield
• Mashing, Baking,
Roasting & Chips
• 17% of Farmers
• Short Dormancy
• 3-4 Mon Maturity
• 35-45/ha Yield
• Mashing, Baking,
Boiling, Roasting
& Chips
• 10.2% of Farmers
• Long Dormancy
• 4-4.8 Mon Maturity
• 35-45/ha Yield
• Boiling, Mashing &
Chips
• Wide adaptability

9. PCR and Southern Blot for Detection of Transgenes in Victoria

10. In-vitro and whole plant assays with P. infestans

11. Extreme resistance to Pi
blb2
3R
Stack gene increased frequency of resistant lines - Durability

12. Lines Selected for Confined Field trial in Uganda
• Kachwekano Zonal Agricultural
Research and development
Institute), National Agricultural
Research Organization (NARO),
P.O. Box 421, Kabale
• 12 transgenic events from
Desiree Extremely Resistant
(ER), Highly R (HR),
Moderately R (MR) based on
whole plant bioassays.
• 1 Transgenic event from
Victoria, ER
• Susceptible (S) Victoria used
as spreader

13. CFT Application and Regulatory Process
NARO
NARO/IBC
NCST /NBC
NCST
MAAIF/CP
CFT Trial
Application forms
Additional literature
Application forms
Additional literature
Additional information
Defense presentation
Decision document
CFT guidelines
Trial mangers hand book
Decision document
Application forms (President’s Office) all researchers
Decision document
Research permit
Request letter
Import permit
UNCST/MAAIF
Reporting and Inspection

14. CFT Location & Design

16. 6 weeks after planting 7 weeks after planting

17. 9 weeks after planting 10 weeks after planting

18. 0
500
1000
1500
2000
2500
Des.1
Des.14
Des.16
Des.21
Des.245
Des.25
Des.254
Des.255
Des.259
Des.260
Des.262
Des.6
Vic.1
Cruz.Control
Vic.Control
Des.Control
AvarageAUDPCValues
Genotypes/Events
Amount of late blight disease Computed as AUDPC
on different genotypes

19. Media and stakeholder visits
Farmers (Uganda Seed Potato Producers
Association, Farmers Forum), the District
Agricultural Officer, Resident district
commissioner (politician), NBC members,
and a journalist from local based radio
station (VOAK).

20. Multi-location Confined Trials

21. Status of GM technology, production, research and
Stewardship in Africa
Under Cultivation
1. Cotton
2. Maize
3. Soybean
Under Field Trials
1. Banana
2. Cassava
3. Cotton
4. Rice
5. Sweet Potato
6. Irish Potato
7. Sugarcane
8. Canola
9. Strawberries
Stewardship in Biotechnology Countries
Malawi, Kenya, Uganda, Nigeria, Ghana & Burkina Faso

22. Perceptions of GMOs in Africa
• If they offer promised benefit
• Disease/pest resistance
• Drought resistance
• 80% would adopt, 90% of which were women
• Regulatory frameworks vary in different countries,
Zambia, Tanzania and Ethiopia extremely restrictive
• Precaution
• Mandatory labeling
• Strict liability provisions
• Tanzania and Ethiopia have amended the law
• Uganda and Kenyan laws more supportive but most
resisted by civil society
• Ban in Kenya
• Delayed enactment in Uganda

23. Potential adoption of GM BBW
Willingness to adopt
GMB-BXW
Projected adoption rate of GM BXW
resistant banana

24. Conclusions
• Gene technology can benefit Africa
• sustain productivity, food and nutritional security
• move agriculture forward to sustain income
• while conserving consumption preferences in Africa
• Farmer’s the beneficiaries will make intelligent
adoption choices; options need to be provided
• Regulatory frameworks will continue to evolve and be
more science based and as more and more
technologies and products are developed.

25. LBr potato team:
• Magembe E., Makoko I., Ghislain M. @ BecA-CIP, Kenya
• Rivera C., Roman, M., Gamboa S., Lindqvist-Kreuze H., Kreuze J. @ ABL-CIP, Peru
• Njoroge A., Forbes G. @ CIP, Uganda, China
• Arinaitwe A., Kiggundu A., Barekye, A., Baguma, G. @ KaZARDI-NARO, Uganda
Partners:
• USAID award ‘Feed the Future Biotechnology Potato Partnership for Indonesia
and Bangladesh’
• MSU-Simplot-CIP
Sponsor:
The LBr team

26. Thank You!