Interactions between the yeasts Tilletiopsis and Pseudozyma and powdery mildew fungi on plants

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The foods that we eat today
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Lecture Outline

• The origins of our foods.
• Genetic modifications of foods through breeding.
• Development of GM foods.
• Advantages and disadvantages of GM foods.
• Issues of concern/controversies.

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Where do the foods that we eat today originate
from?
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Centres of origin of food plants

• A total of 9 different geographic regions were
  identified world-wide.

• I. Chinese Centre 136 species
• II. Indian Centre
• A. Main 117 species
• B. Indo-Malayan 55 species
• Central Asiatic Centre 43 species
• Near Eastern Centre 83 species
• Mediterranean Centre 84 species
• Abyssinian Centre 38 species
• South Mexican and Central American Centre 45
  species
• South American Centre 62 species

After Vavilov, Origin, Variation, Immunity, and
Breeding of Cultivated Plants, Ronald Press,
N.Y., 1951
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After Vavilov, Origin, Variation, Immunity, and
Breeding of Cultivated Plants, Ronald Press,
N.Y., 1951
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Genetic diversity in potato
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Potatoes sold in a market in Lima show
considerable diversity.
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The origin of the carrot is from Central Asia.
The orange form is rare in nature and developed
from a mutation.
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The origin of the cucumber is from India
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Objectives of genetic modifications through
breeding
Breeding efforts have been on-going for centuries
to modify wild crop species.

• Enhanced yield and quality.
• Uniform crop growth.
• Resistance to pests and diseases.
• Tolerance to environmental stresses.

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The breeding process
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Specific genes are located on chromosomes, giving
rise to specific traits
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Genetic diversity provides a basis from which to
select derived types
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Modifications through breeding
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Our current tomatoes were derived from small
green, hard, bitter fruits
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Consider these botanical monstrosities, derived
from breeding!
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The elimination of seeds in foods
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• Todays agricultural production is far removed
  from Nature, utilizing highly bred genetic
  material, requiring high inputs (fertilizer,
  fuel), to satisfy the needs of humans.

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Lettuce production, Salinas Valley, CA
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Lettuce field, Cloverdale, BC
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Currently-bred plants are high yielding
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Currently-bred plants have optimal quality
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Currently-bred plants are genetically uniform
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Unintended effects resulting from breeding

• Barley enhanced susceptibility due to mildew
  disease.
• Squash natural toxins causing food poisoning.
• Celery higher levels of carcinogenic compounds
  (psoralens).
• Potato high levels of toxin (solanine).

NOTE All the above foods were withdrawn from
the market.
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Genetic engineering

• Specific genes, from any biological source,
  encoding a specific protein, can be introduced
  into a crop plant.
• The end-result is the expression of novel
  protein(s) which give rise to a GM food.
• The methods require recombinant DNA technology,
  as opposed to traditional breeding methods.

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Modifications through genetic engineering
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The Vancouver Sun
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How does genetic engineering work?

• The chemical composition of DNA is the same in
  all living organisms.
• The differences lie in the gene product.

PROTEINS
DNA double helix structure
Protein structure
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Gene transfer requires insertion of DNA into the
nucleus
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Specific new genes are added to the existing
genetic material
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Genetic engineering methodology
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Techniques are available to identify the novel
genetic material
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Cells containing the new genes are regenerated
and grown
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Plants containing the new gene are produced in
the laboratory from individual cells.
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Our research interests in GM foods

• 1. Fungal diseases can reduce quality,
  appearance and shelf-life with few effective
  control methods available.
• 2. Transfer of genes coding for antifungal
  proteins (from bean, petunia, rice) can reduce
  rate of disease development.

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Fungal diseases can reduce quality and shelf-life
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Fungal diseases can cause devastation
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Can fungal-free crops be produced?
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Transgenic plant response to disease
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A little publicity never hurts!
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Plant species under study
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HOW DO GM FOODS GET ONTO THE MARKET?

• Laboratory research takes about 4 years
  (introduction of a novel trait).
• Field trials are needed over 2 3
  years/locations (expression of trait).
• Precommercial trials are needed to collect data
  for environmental and food and feed safety.
• Regulatory approval and scale-up production.
• Can take 8 10 years, at a cost of 10 million.

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Worldwide production of GM foods
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Herbicide and insect resistant GM crops

• Herbicide resistance allows farmers to manage
  weeds using herbicides at all times and to reduce
  other inputs eg soil tillage.
• The use of the particular herbicide increases.
• Insect resistance allows farmers to manage
  insects with reduced levels of pesticides.
• Resistance build-up in the insect and spread of
  the trait are continuing concerns.
• Both farmers and GM producers have experienced
  increased profit margins.

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Transgenic crops approved for use in Canada
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Who oversees the safety of GM foods in Canada?
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Unintended effects from GM technology

• Barley inferior malting quality.
• Corn more lignified tissues that degrade
  slowly.
• Canola increased sensitivity to herbicide.
• Potato lower yield.

• NOTE These effects were noted in field trials or
  production fields.

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Issues of concern over GM foods

• Health-related (increased allergenicity, new
  toxins, unintended effects).
• Environmental (spread of genes, impact on other
  organisms, unanticipated effects).
• Economic (cost of the technology, corporate
  control over food, patent issues).
• Political (trade issues, impact on developing
  countries, consumer back-lash).
• Social/ethical/religious.

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1. Specific health-related data is required for
each GM food

• Levels of novel proteins throughout the plant
  (exposure).
• Comparison to all known allergens/toxins
  (allergenicity).
• Stability/fate of proteins following ingestion
  (toxicity).
• Levels of major nutrients in the plant
  (nutrition).
• Limited feeding trials (mice, chickens).

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2. Environmental issues of concern

• Spread of the introduced gene.
• Impact on non-target species (biodiversity).
• Possibility of creating a potentially dangerous
  (irreversible) situation.

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Many, but not all, plants produce flowers
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Source Agriculture and Agri-Food Canada,
Saskatoon
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Flowers release pollen which can be spread by
wind, insects, humans to nearby areas (genetic
pollution)
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Impact of pollen spread

• Transmission of genes from genetically engineered
  plants can occur, but only to the same species or
  to a sexually-compatible closely related
  species.
• There is little scientific evidence to indicate
  that the transfer of a GM trait to a weed species
  will enhance its fitness, unless selection
  pressure is brought upon the population.

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Does B.t. pollen harm Monarch butterflies?
Research article, Nature, May 20, 1999
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The Monarch butterfly concern

• Laboratory experiments feeding GM pollen from
  corn to the butterflies showed a high mortality.
  Immediate concerns were raised over GM crops with
  B.t. resistance.
• Later studies showed that the levels of pollen
  fed were much too high and that butterflies were
  not significantly exposed to GM pollen in corn
  fields, feeding instead on other plants eg
  milkweed.

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3. Economic issues of concern

• Company mergers are leaving only 3 4 big
  players in the plant biotechnology arena eg
  Monsanto (Calgene, Mogen), Aventis (Hoechst,
  Rhone-Poulenc), Syngenta (Ciba-Geigy, Sandoz).
• Most discoveries are being patented and
  information is only disclosed through licensing
  agreements, providing limited access.

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US Patent and Trademark Office Agricultural
biotechnology
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4. Political issues of concern

• The European Union, Australia, and other
  countries placed a 5-year moratorium on GM foods
  (1998 2003). This prevented importation of
  these foods from the U.S. and elsewhere.
• Consumer back-lash in Europe has reflected a
  mis-trust of government and multi-national
  corporations, a strong environmental movement,
  and a desire to be far removed from North
  American agriculture.

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Why did GM foods stir up such a controversy?
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• Biotechnology companies have been aggressive in
  bringing these products to market.
• Consumers have not been provided with factual
  information or had adequate discussion about the
  benefits of this technology.

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The New York Times
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Controversial issues

• The Precautionary Principle should it be
  applied to GM foods?
• Labelling of GM Is it meaningful and useful for
  consumers/trade partners?
• Do we really need GM foods?

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Precautionary Principle

• When an activity raises threats to human health
  or the environment, precautionary measures should
  be taken, even if some cause and effect
  relationships are not fully established
  scientifically.
• - what level of threat is needed?
• - how do we identify measures against an
  unproven?
• - does the activity have a benefit?
• - are there any activities without threats?

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Labelling of GM food products

• Should the label specify the process used to
  derive that product?
• Should the label specify the ingredients that
  must include the foreign protein introduced?
• A label is required where significant
  nutritional/compositional changes occur.
• In many cases, GM ingredients in food are at
  undetectable levels.

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A recent study (Sept, 2003) indicates that
mandatory labelling with may contain GM
ingredients will not provide consumers with
perceived value.
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Why are GM foods needed?

• There is a continuing loss of genetic diversity
  among plant species.
• The global human population is continuing to
  increase and challenges to sufficient food
  production remain.

GM foods can enhance crop yield
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Genetic diversity such as this is becoming rare
to find
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Why are GM foods needed?

• Enhanced tolerance to pests and diseases with
  reduced chemical use is needed.
• Enhanced tolerance to environmental stresses, eg
  drought, pollution, temperature extremes is
  needed.

Novel GM crops with enhanced tolerance to these
stresses are being developed
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Why are GM foods needed?

• Increased vitamin and nutrient levels and
  improved shelf-life can be achieved.
• Plant derived sources of pharmaceutical products
  and chemicals can be accomplished (vaccines,
  therapeutic proteins).

Novel GM foods have been developed
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Rice a primary staple food worldwide
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Golden rice contains novel expression of
pro-vitamin A
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Why are GM foods needed?

• Global climate changes and increased
  environmental stresses are impacting plant
  growth.
• New technologies need to be implemented to
  address changing needs.

GM foods are just one of a number of new emerging
technologies
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Some recent developments on GM foods

• The EU has approved mandatory labelling of foods
  if they contain GM ingredients at gt0.9.
• Sensitive methods to detect the presence of GM
  ingredients in foods are available.
• Food safety assessments procedures are
  continuously under review.

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Some novel GM foods under development
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What is still needed?

• Appropriate risk assessment over broad ecological
  regions.
• Cost/benefit analysis relative to consumers.
• Post GM food surveillance.
• Educating consumers about the technology.

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Conclusions

• This is an exciting technology that is here to
  stay.
• Understanding the facts and asking the right
  questions will help to dispel many concerns.
• Political and social issues remain of primary
  concern.

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