What are Genetically Modified
Crops and how are they made?
Professor Idah Sithole-Niang
Department of Biochemistry, UZ
GMASSURE - UZ
Outline
• Definitions
• Concept of Genetic Modification
• Agricultural context
• Why biotech?
• Challenges/Opportunities
• Status & specific opportunities in Africa
• Non-GM products
Definitions
• Biotechnology is the use of biological
systems to create goods and services
• Gene manipulation
• Genetic engineering
• Genetic modification
• Transgenesis
– LMOs: living modified organisms
– GMOs: genetically modified organisms
Concept of Genetic Modification
through plant transformation
Identify genes of interest for a trait (eg. insect
resistant genes)
Insert into an organism of interest (eg. Insert
insect resistance gene into a susceptible plant to
make it resistant) – very common with crop plants
Genes can come from a variety of sources:
From the same plant species
From wild relatives
From another crop
From bacteria or another organism
Agricultural context
Cross breeding and induced mutation are important tools of plant breeding, they also have limitations:
1. Cross breeding only works between related plants.
2. For some species cross breeding is extremely difficult.
3. Cross breeding can take very long.
4. ‘Linkage drag”
5. Mutation is very undirected and unpredictable, HORIZONS sprl
Genetic Modification of Plants
Traditional
plant breeding x
“elite”
variety
Related
variety
Genetic
Modification
any
gene
source
HORIZONS sprl
Genetic Modification of Plants
Technical advantages:
• Specific
• Faster
• Possible with plants that do not
cross sexually
• Much greater reservoir of genes
HORIZONS sprl
Generating Varieties of Agricultural
Plants and Animals • Conventional breeding
– Crossing of two varieties with useful characteristics
– Hybrids
– Tissue culture
– Cloning
– Chemical mutagenesis
– Irradiation
– In vitro fertilization
– Artificial insemination
Using Radiation to Create Mutant Varieties of
Plants
Gamma Rays X Rays
Genes carry the information that is
passed from generation to
generation. They are the blueprint
of life
Anything that is alive has genes.
The information of genes is carried
in the form of DNA molecules.
The ‘language’ of DNA, is the same
regardless of the organism – A key
point for genetic engineering
DNA molecule
Breeders, geneticists, and genetic
engineers work with genes
Genes carry the
information that is
passed from generation
to generation. They are
the blueprint of life
DNA molecule
Breeders, geneticists, and genetic
engineers work with genes
Anything that is alive has
genes.
The information of genes
is carried in the form of
DNA molecules.
DNA molecule
Breeders, geneticists, and genetic
engineers work with genes
The ‘language’ of DNA
is spelt out in a simple
alphabet of 4 letters
A, C, G, T
DNA molecule
Breeders, geneticists, and genetic
engineers work with genes
The ‘language’ of DNA,
is the same regardless
of the organism – A key
point for genetic
engineering
DNA molecule
Breeders, geneticists, and genetic
engineers work with genes
Sigma ad 8/2008
How much of your
DNA sequence do
you share with a
banana?
A: None
B: 1%
C: 10%
D: 50%
E: 90%
Good grief!: I’m a banana!
You and Your DNA
Do you know that humans
share about 50% of their DNA
with a banana!
Getting genes into cells – plant transformation
2. Put the
engineered gene
into cells of the
desired plant
Step X step
Dr. Mufandaedza
Regulation of GM crops moves
through different stages of crop
development and deployment
Lab
Growth
Chamber or
greenhouse
Confined Field
Trials
General
release
Full safety
assessment
CFT Application General Release
Application
Approval
1. Why biotechnology?
• World population will reach 9 billion by 2040
• Some undernourished either in terms of both
quantity or quality
• Arable land shrinking due to erosion, pollution,
and other forms of land use
• Increasing shortage of fresh water for drinking
and irrigation
• Climate change will increase the need for
keeping up with well adapted crops
2. Why biotechnology ?
• Increasing demand for fuels and
chemicals from renewable sources as oil
reserves become depleted and oil-based
commodities more expensive
• 80% of world caloric intake comes from
only 4 crops
• Not a silver bullet but can contribute
significantly to finding solutions to these
challenges
1.Challenges
• Need to produce:
–More crops per hectare
–More crop per liter of water
–Marginal-
–Arid- or Saline land
2. Challenges
Enhance:
• Nutritional value of crops
• Crop diversity
Reduce:
• Dependency on pesticides & fertilizers
• Post-harvest losses during storage &
transport
• Soil erosion
Do these challenges apply to
Zimbabwe?
What are the Opportunities'?
1. Opportunities/pipeline
Biotic stress: Disease resistance
• Fungal resistance – Banana/Black
sigatoka
• Virus resistance – banana, cassava, yam,
papaya, groundnut, sweetpotato & tomato
• Bacterial resistance – rice, cassava,
banana & potato
• Pest resistance/field & storage
2. Opportunities/pipeline
Abiotic stress tolerance
• Drought tolerance –maize (WEMA),
wheat rice sorghum etc
• Salinity tolerance- maize, wheat,
tobacco, sorghum, rice etc (NUWEST)
3. Opportunities/pipeline
Enhanced nutrition: rice, cassava &
sorghum –(pro-vitamin A, Fe, Zn, Vit E)
• Banana- pro-vitamin A & Fe, wheat- Fe
• Maize, potatoes, sorghum & cassava
(protein quality). Mustard pro-vitamin A
• Others: reducing cyanogenic compounds
in cassava & changing available P by
reducing phytates
You mean there are all these
wonderful Opportunities!!!!??
Why the controversy?
What are the issues??
Mr Dhlamini
Any Good examples in the
BRICS?
BRAZIL, CHINA & INDIA
Prof CJC
What would it feel like if the
DR & SS had $1 billion budget?
What would it feel like if the NBA reviewed, 14
applications annually???
Whos Who In Africa?
and where are they with their
regulation?
Dr. Mufandaedza
Developing high quality
Pod-borer-resistant cowpea varieties Problem
• Insect damage in the field and in
storage
• Losses can be up to 80%.
• Frequent insecticide sprays
required
• Host plant resistance is a low-cost
and environmentally friendly control
measure for the farmer
Product
High yielding cowpea varieties with
increased resistance to insect pests -
Bt-Cowpea
(Pod borer- Resistant Cowpea) Figure 7. Pod damage by M. vitrata
Resistance to Banana Bacterial Wilt
for East African Highland Bananas
Constraint:
Banana bacterial wilt (BBW) disease caused by the bacterium
Xanthomonas campestris pv. musacearum (Xcm)
• Africa drought-prone
• Maize is the most widely grown staple crop in Africa – affected by drought
• In 2003 WFP spent $0.57b on food emergency due to drought in Africa
Recorded droughts between 1971 and 2000, and the number of people affected
Water Efficient Maize for Africa
(WEMA)
Drought tolerant Maize
Is there a drought in
Zimbabwe??
Do some of these solutions
apply??
Gene silencing line (with
gene to control CMD)
Susceptible
(without the
gene)
Confined Field Trial to Evaluate Transgenic Cassava for Resistance to Cassava Mosaic Disease
- D3/2/NBC/4/08
Symptomless leaves and stems of best test line (1-718-001)
Severe streaking and dieback on control line without gene
Symptoms of CBSD at Harvest: CBSD Study
What will you have for dinner???
Best test line; No rotting of
the storage roots Control line without the
gene; severe rotting of roots
Symptoms of CBSD at Harvest: CBSD study
Eggplant (Brinjal or Talong)
Fruit and Shoot Borer
This damage is prevented by Bt.
Bt cotton CFT in Malawi 2013
Mr. Mhandu
Biotech crops on trial in Africa • RSA: potatoes, sugarcane, maize
• WEMA : RSA, Kenya, Uganda
• Kenya: cotton, maize, SP, cassava
• Egypt: cotton, potato, wheat, cucumber, melon
• Uganda: banana, cotton ,cassava ,maize, rice
• Nigeria - cowpea, cassava, sorghum
• Burkina Faso: cowpea, rice
• Malawi – cotton, cowpea , banana
New Breeding Technologies
Non- GM Technologies
Need we even dream???
Non-GM: Genome editing
technologies • CRISPRs: clustered regularly interspaced
short palindromic repeats
• ZFNs: Zinc finger nucleases
• TALENs : transcription activator-like
effector nucleases
Zinc Finger Nucleases
• Successfully used to introduce herbicide
tolerance = WEED CONTROL
TALENs
• Used to delete and cut out a gene in rice
that confers susceptibility to bacterial
blight disease
CRISPRs
• Chinese Academy of the Sciences
developed a powdery mildew-resistant
wheat through advanced gene editing
• Example of modification of a food crop
without using insertion foreign genes
Three Requirements for growth
of GM crops in Africa
• Political will and support from lead
countries, governments and institutions
• Establishment of responsible and
efficient regulatory systems, that are
appropriate for Africa given the limited
resources
• Communication with Society
transparently and accurately
Thank you for your attention
Acknowledgments
• Clive James, ISAAA
• Cholani Weebadde, Michigan State
University
• Peter Davies, Cornell University
• Program for Biosafety Systems
• African Biosafety Network of Expertise
• GMASSURE
• African Agricultural Technology Foundation
Current Status of Genetically
Engineered Crops • Grown in over 28 countries around the world by over
18 million farmers – 420 million acres in 2013
• Largest in acreage – US (171 million acres)
• Largest in terms of farmers – India and China – 14 million farmers
• Types of products – maize, soybeans, cotton, canola, sugar beets, alfalfa, squash, papaya
• Types of traits – built in pesticides, resistant to herbicide, resistant to virus
• For the first time in 2012, developing countries grew
more, 52%, of global biotech crops in 2012 than
industrial countries at 48%
Drought and African Agriculture
• The WFP spent $0.565B of food emergency to respond to drought in sub-Saharan Africa (SSA) in 2003
• Over 95% of cropland in SSA is rain-fed and will remain so in the near future
• The risk of drought prevents investment in improved agricultural products
Yield stability is key to unlock the value of basic inputs
Recorded droughts between 1971 and 2000, and the number of people affected
(Slide source: Dave Songstad, Monsato)