Genetic Engineering

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11 Δεκ 2012 (πριν από 4 χρόνια και 11 μήνες)

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Genetic Engineering

The risks to (food), farming
& biodiversity
Dr. Ricarda A. Steinbrecher
Econexus
Barcelona, 7 March 2009


Genetically Modified Organisms
Sustainable
Agriculture
Human and Animal
Health
Socio-
economics
Food
Security
Democracy
Ethics &
Religion
Power and
Control
Scientific
Uncertainties
Environment
Contamination
Biodiversity
Issues
&

Concerns
Regulation &
Legislation


Central Tenets of GM in Agriculture
The use of genetic modification (GM) in
agriculture is a
natural extension
of
traditional breeding methods but more
precise, faster
and
safer
.
Genes are isolated units of information that
can function in a totally predictable manner
even when moved between unrelated
species using GM technology.


cells


cells
nucleus


cells
nucleus
chromosome
DNA
gene


cells
nucleus
chromosome
DNA
gene
T
A
A
A
C
C
C
G
G
G
T
T
T
A
Basepairs: A-T & C-G (
nucleotides
)


Genes and Genetics: The Fundamentals
“The New Genetics”
1. Gene order & organisation in DNA is very precise.
3. Genes exist in groups or families.
4. Genes work in groups; no gene works in isolation.
5. Gene function is tightly regulated in a highly coordinated manner

by both local and distant genetic elements and layers of
epigentic

control.
2. In most cases, more than one RNA/protein is produced from a

given gene.


6.
Genes have
co-evolved
to function together as an integrated whole
within a given organism.
Normal sexual reproduction or breeding can take place only between
closely related organisms. Genes are inherited in their natural
groupings that have been finely tuned to work harmoniously together
by millions of years of evolution
Genes and Genetics: The Fundamentals
“The New Genetics”


"In everyday language the talk is about a gene
for this and a gene for that. We are now
finding that that is rarely so. The number of
genes that work in that way can almost be
counted on your fingers, because we are just
not hard-wired in that way."
 
Craig Venter, Celera Genomics, 12 February 2001
Genes and Genetics: The Fundamentals
“The New Genetics”


1. Isolate resistance gene

such as Bt-toxin gene from
Bacillus thuringiensis
2.

Make a gene construct that

will work in plants



3...
4...

5...
How does Genetic Engineering

work?
Aim: e.g. to make rice insect resistant



1. Isolate resistance gene

such as Bt-toxin gene from
Bacillus thuringiensis
2.

Make a gene construct that

will work in plants



3...
4...

5...
How does Genetic Engineering

work?
Aim: e.g. to make rice insect resistant





1. Isolate resistance gene

such as Bt-toxin gene from
Bacillus thuringiensis
2.

Make a gene construct that

will work in plants



3...
4...

5...
How does Genetic Engineering

work?
Aim: e.g. to make rice insect resistant











Gene construct
promoter

Gene for trait
(Bt toxin)

end



Regulatory sequence: on/off switch
-
often CaMV (virus)
Coding sequence
of a gene -
e.g.
pat
or
bar
gene for herbicide
resistance from soil bacteria
LL-rice
Regulatory sequence: Termination signal -
e.g. from pea

Plasmid backbone DNA, superfluous genetic material


1.
Isolate resistance gene

2.
Make a gene construct that

will work in plants



3.
Prepare plant cells or tissue
4.
Transform plant cells

5.

How does Genetic Engineering

work?



Aim: e.g. to make rice insect resistant


















Transformation



?


Transformation



?
Agrobacterium
used as “shuttle”





Transformation



?
Agrobacterium
used as “shuttle”



Particle
bombardment


Transformation



?
Agrobacterium
used as “shuttle”



Particle
bombardment


Transformation



No control of where the gene will insert itself:



Random integration


Imprecision
(incl. superfluous DNA)


100 -1000s of Mutations
(Sala et al. 2000, Wang et al. 1996, Labra et al 2001)
?
Agrobacterium
used as “shuttle”



Particle
bombardment


1.
Isolate resistance gene
*
2.
Make a gene construct that

will work in plants

*

3.
Prepare plant cells or tissue
4.
Transform plant cells
*

5.
Regrow cells to plants via tissue culture
*
*
Steps that contain scientific uncertainties and
risk potential

How does Genetic Engineering

work?



Aim: e.g. to make rice insect resistant


















The GM Transformation Process
(A)
PDS/1000 biolistic device used for microprojectile bombardment.
(B)
Suspension cells of tall fescue plated on filter paper before microprojectile
bombardment.
(C)
Hygromycin resistant calli obtained after selection.
(D)
,
(E)
Transgenic plantlets regenerated from the hygromycin resistant calli.
(F)
Transgenic tall fescue plants growing in the greenhouse.


Scientific Uncertainties (1)

Introduction of mutations

by Agrobacterium and particle bombardment

through tissue culture

Cre/lox system is no answer

Examples:


Haemophilia …
Allison Wilson, Jonathan Latham, Ricarda Steinbrecher (2004).
Genome
Scrambling – Myth or Reality?
Transformation-Induced Mutations in Transgenic
Crop Plants.
EcoNexus - Technical Report.
http://www.econexus.info
Latham JR, Wilson KA and Steinbrecher RA (2006)
. The mutational
consequences of plant transformation. Journal of Biomedicine and Biotechnology.
Art. No. 25376 22006


Scientific Uncertainties (2)

Altered Gene Regulation


Choice of promoter:

constantly switched on (e.g. CaMV)

overproduction

leakage: neighbouring genes switched on

expression in other organisms


Position of insertion site


pleiotropic
” effect of gene

Examples

Enhanced lignin production in RR soya and Bt corn


Lignin overproduction (1)

RR Soya
:
herbicide tolerance to glyphosate

20% increase of lignin production at 25

degrees
Celsius

Tissue tears and the stem splits at sudden increase of
growing temperature: vulnerable to fungal attack.

Gertz JM et al. (1999). Tolerance of transgenic soybean (
Glycine max
) to heat stress,
Paper given at The 1999 Brighton Conference of the British Crop Protection Council.
Also Andy Coghlan, "Monsanto’s modified soya beans are cracking up in the heat -
Splitting headache,"
New Scientist
, 20 November 1999.


Lignin overproduction (2)

Bt Corn
:
insect resistance using Bt-endotoxin
gene from
Bacillus thuringiensis
(1): stems of MON810, Bt11 and Bt 176 by
33 to 97%
(2): stems of Valmont (MON810) by
18%


and Novelis (SYN 176-9) by
28%
(1) Saxena D, and Stotzky G (2001). Bt corn has a higher lignin content than

non-Bt corn.
American Journal of Botany
88, 1704-1706
(2) Poerschmann J et al. (2005).
J Environ Qual
34:1508-1518


Scientific Uncertainties (3)

Gene Silencing

Especially GE-genes (transgenes) are effected.

Environmental stress can be the trigger

Examples:

30.000 petunia plants

Consequences
:

a) Unreliable gene performance.
b) Risk of lowered nutrient levels, or enhanced levels of anti-
nutrients, toxins or allergens.

c) Consequences can also be a weakened agricultural
performance of the GE crop, thus resulting in yield loss.
Meyer P, Linn F, Heidmann I, Meyer H, Niedenhof I, and Saedler H (1992) Endogenous
and Environmental-Factors Influence 35s Promoter Methylation of a Maize A1 Gene
Construct in Transgenic Petunia and Its Color Phenotype.
Molecular & General Genetics

231, 345-352


Scientific Uncertainties (4)
· Other unpredictable effects:
1.
Significantly increased levels of the cotton toxin
gossypol in cotton seed harvested from
Monsanto’s
RR herbicide tolerant cotton
2.
68-fold reduced level of beta-carotene (pro-
vitamin A) and 4-fold increased sodium level in
transgenic squash
(CZW-3) approved for
commercialisation in the US
(1) Meyer H (1999) Precise precaution versus sloppy science.
Bulletin of Science,
Technology and Society
19, 91-95
(2) USDA Application 95-352-01p - approved for commercialisation


Implications and Risks

Health
(not covered here)

Contamination

Environment

Biodiversity & Agro-biodiversity

Sustainable Agriculture

Food Security


Contamination
Of concern is contamination of

Food
(e.g. Starlink, Pharma crops, LL rice, Bt rice)

Food crops – cross pollination
(canola, wheat,
LL rice)

Seed
(UK: Avanta canola; US: LL601, 06 & 62 rice)

Wild or cultivated relatives

Centres of origin
(Maize in Mexico)


Environmental Risks
Impact on

Pollinators (e.g. Bees US.
Kaatz 2007
)*

Beneficial organisms, e.g. lady birds, lacewings
(e.g.
Hilbeck et al. 1998 vs Romeis et al. 2006; Loevei & Arpaia 2005
)

Moths, butterflies

Soil food web - Plant interaction
(Castaldini 2005)
*

Invasiveness
(superweeds, e.g. RR soya in Argentina)

Forests

(soya in Argentina)
Emergence of Secondary Pests
(e.g. Wang et al)
*
Co-evolution out of step


Bees: Colony Collapse Disorder
Bee loss is gaining serious proportions in many
countries
(2006 : 70% east coast; 60% west coast US)



Dr. Hans-Hinrich Kaatz (Univ. of Halle, Germany)
conducted feeding trials on honeybees at University of
Jena, Germany, from 2001-2004.


Feed: Pollen from Bt corn (Cry1Ab)


Healthy honey bees - no effect


If infected with parasite (mites??): death rate substantially
higher, esp. with increased Bt levels.


Conclusion by researcher
: Bt pollen is a likely
contributory factor to CCD


Bt cotton & secondary pests

China: mirids
(new)

India & Pakistan:
mealy bug (new)

Africa: different
(re-emerging)
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.


Wang, S., Just, D.R. and P. Pinstrup-Andersen.
Tarnishing Silver Bullets: Bt technology adoption, bounded
rationality and the outbreak of secondary pest infestations in China.

Paper presented at American Ag. Econ. Assoc. annual meeting, Long
Beach, CA, 22-26 July, 2006


Wang, S., Just, D.R. and P. Pinstrup-Andersen.
Tarnishing Silver Bullets: Bt technology adoption, bounded
rationality and the outbreak of secondary pest infestations in China.

Paper presented at American Ag. Econ. Assoc. annual meeting, Long
Beach, CA, 22-26 July, 2006

Household survey of 481 farmers, 20 villages, 5
provinces: Hebei, Shandong, Henan, Anhui, Hubei


Wang, S., Just, D.R. and P. Pinstrup-Andersen.
Tarnishing Silver Bullets: Bt technology adoption, bounded
rationality and the outbreak of secondary pest infestations in China.

Paper presented at American Ag. Econ. Assoc. annual meeting, Long
Beach, CA, 22-26 July, 2006

Household survey of 481 farmers, 20 villages, 5
provinces: Hebei, Shandong, Henan, Anhui, Hubei

Results for 2004:

Average expenditure on pesticides was same ( US$101/ha)
between Bt and non-Bt farmers

Bt farmers spend 46% less on bollworm pesticide, but spend
40% more on pesticides for secondary pest(s), compared to
non-Bt farmers

Main secondary pest – mirids

GM cotton seeds cost 3 times more than non-Bt cotton, so Bt
farmers make less money than non-Bt farmers

Results markedly different from data from 1999, 2000, 2001


Wang, S., Just, D.R. and P. Pinstrup-Andersen. Tarnishing Silver
Bullets: Bt technology adoption, bounded rationality and the outbreak
of secondary pest infestations in China.
Paper presented at American Ag. Econ. Assoc. annual meeting, Long
Beach, CA, 22-26 July, 2006


Wang, S., Just, D.R. and P. Pinstrup-Andersen. Tarnishing Silver
Bullets: Bt technology adoption, bounded rationality and the outbreak
of secondary pest infestations in China.
Paper presented at American Ag. Econ. Assoc. annual meeting, Long
Beach, CA, 22-26 July, 2006


Wang, S., Just, D.R. and P. Pinstrup-Andersen.
Tarnishing Silver Bullets: Bt technology adoption, bounded
rationality and the outbreak of secondary pest infestations in China.

Paper presented at American Ag. Econ. Assoc. annual meeting, Long
Beach, CA, 22-26 July, 2006


Benbrook, C. 2004. Genetically engineered crops and pesticide use in
the United States: The first nine years. At: http://www.biotech-
info.net/Full_version_first_nine.pdf


Impacts on Soil food web
Dealing with 2 types of pesticides
-
Bt toxins: insecticides

-
Herbicides:
-
Glufosinate (LibertyLink system)
(herbicide
broken down by GM plant)
-
Glyphosate (RoundUp) -
fusarium


Castaldini et. al (2005).
Impact of Bt Corn
on Rhizospheric and Soil
Eubacterial Communities and
on Beneficial Mycorrhizal Symbiosis

in Experimental Microcosms.
Appl.Environ.Microbiol
.71(11):6719-6729
<http://aem.asm.org/cgi/reprint/71/11/6719>


Agricultural Challenge

If GM is the answer - what was the question?”

Technology centred approach vs solution
centred approach

Technofix - instant gratification?..and then?
What about:

Yield increase?

Drought resistance? Flood resistance?

Feeding the world?


Agriculture: Yield Increase (1)

There is no GM crop that has been
engineered for increased yield: ht & ir (dr)

An analysis of current scientific reports on
yield performance of GM crops has shown
yield decreases, yield lags, reduced loss in
case of high pest infestation in the short term,
no longterm benefits.

High degree of indirect negative impacts
(fusarium, secondary pests, spread of rust)
Steinbrecher and Lorch (2008). Feed the world. The Ecologist, Nov., pp.20-22


Agriculture: Yield Increase (2)

LER (Land equivalent ratio) shows that
agro-ecological systems such as mixed
cropping produce higher yields than
conventional monoculture systems.
Steinbrecher and Lorch (2008). Feed the world. The Ecologist, Nov., pp.20-22
A
B
A+B=1
A+B= up to 1.8
Ethiopia: wheat + faba beans: 1.2
Brazil: root veg + onions: 1.5
Mexico: Maize, squash, beans: 1.73


Agriculture: Yield Increase (3)

Using leguminous cover crops could
replace the synthetic nitorgen fertilisers

In the South, agro-ecological & organic
systems produce 80 more than
conventional systems, with organic inputs
easily accessible.


Push & Pull – East Africa / Kenia
Problem for maize yield
:
Stem borer (eg
chilo partellus
moth
) effect a third
of the region’s maize crop.
Scientists of the
Mbita Point Research Station,
Lake Victoria, Kenya came up with a simple
solution
:

Pull
:
Napier grass (up to 70% yield increase).


Push
:
Desmodium
, a common l
egume “weed”
species, repels the stem borer
Secondary benefits:

Desmodium
enriches soil with nitrates, prevents
soil erosion during rains and suppresses the
growth of Striga weed,
a parasitic plant causing
US
$ 10 billion yield loss/year (
effecting 100
million Africans
).

Napier grass can be used and sold as fodder.




Rice farming:
(Philippines)
IRRI:
20 x 20 cm
MASIPAG:
10 x 40 cm


Airport Kuala Lumpur, Malaysia, March
2004.
Departure from MOP1 to the Cartagena Biosafety Protocol




Genetically Modified Organisms
Sustainable
Agriculture
Human and Animal
Health
Socio-
economics
Food
Security
Democracy
Ethics &
Religion
Power and
Control
Scientific
Uncertainties
Environment
Contamination
Biodiversity
Issues
&

Concerns
Regulation &
Legislation