Transcript Plant engineering - Iowa State University

The perpetual search for improvement
PLANT ENGINEERING
SALUTE TO NORMAN E. BORLAUG
Father of “Green Revolution”
Iowa native and Nobel Laureate (1970) used Biotechnology
and modern farming practices to combat world hunger.
Dr. Borlaug’s development of high-yield and disease-resistant wheat
varieties bore results in Mexico, Pakistan and India that stretched the
imagination of viable agriculture in developing countries. Recently,
Borlaug worked to apply farming practices and methods of increasing
food production to Asia and Africa, and he has continued to
advocate for the use of biotechnology to combat world famine.
Established the World Food Prize in 1987 and expanded this
with the help of John Ruan of Des Moines in 1990.
Died September, 2009 at the age of 95.
PLANT CLONING
Leaf or root cutting from a plant
grown into a new plant
(vegetative propagation) –
cloning – same genetic
makeup as the donor plant.
Vegetative propagation: cutting
forms a mass of non-specialized
cells – callus
Callus grows, divides and forms
various specialized cells (roots,
stems) new plant.
CLONING APPROACHES
Leaf cuttings Stem of a leaf in soil new plant, e.g. African violets, snake plants, gloxinia,
and begonias. Some plant leaves, when cut from their stems and placed flat on top of the
soil, develop roots at particular intervals along the cut veins of the leaf. The parent sprouts
several baby plants, all growing vertically from the leaf at various points along the veins,
e.g.begonia and geranium.
Stem cuttings Piece of stem inserted in soil horizontally or vertically. Roots develop
downward from stem  new plant from top. Stem with bud cut from plant,  new plant
from bud, e.g: begonia, gardenia, christmas cactus, lantana, and impatiens.
Budding Common in propagation of many fruit trees. A bud, which is an undeveloped
branch, leaf or flower protruding from the stem of the plant, cut from parent, placed into a
notch made into the parent stem, wrapped in place and allowed to grow until it can be
removed from the parent and allowed to grow in soil on its own.
Plant division Many flowers, such as the commonly found daylily, hostas, certain orchids,
and ferns, are cultivated through the division of their thick roots.
Runners Wild strawberry plants, e.g., put out horizontal stems that touch the soil.
These develop roots from which another identical strawberry plant will grow.
Grafting Cutting from plant attached to a piece of the root, or to the rooted stem of another
plant. The pieces become united, and grow as one plant. Desirable properties of each plant
can be mated to produce a new hybrid plant without producing hybrid seeds, e.g. producing
dwarf fruit and oriental trees for home landscaping
MERISTEM CLONING
GENES AND CHROMOSOMES
The total complement of genes in an
organism or cell is known as its genome,
which may be stored on one or more
chromosomes; the region of the
chromosome at which a particular gene
is located is called its locus.
This diagram shows a gene in
relation to the double helix
structure of DNA and to a
chromosome (right). The
chromosome is X-shaped
because it is dividing. Introns
are regions often found in
eukaryote genes that are
removed in the splicing
process (after the DNA is
transcribed into RNA): Only the
exons encode the protein. This
diagram labels a region of only
50 or so bases as a gene.
In reality, most genes are
hundreds of times larger.
MENDELIAN INHERITANCE
Crossing between
two pea plants
heterozygous for
purple (B, dominant)
and white (b,
recessive) blossoms
DNA CHEMISTRY
The chemical
structure of a fourbase fragment of a
DNA double helix
MUTATIONS
DNA replication is extremely accurate, with an error rate per site of around 1 in 10−6 to 10−10 in
eukaryotes. Rare, spontaneous alterations in the base sequence of a particular gene arise from a
number of sources, such as errors in DNA replication and the aftermath of DNA damage. These
errors are called mutations. The cell contains many DNA repair mechanisms for preventing
mutations and maintaining the integrity of the genome; however, in some cases—such as breaks
in both DNA strands of a chromosome — repairing physical damage to the molecule is a higher
priority than producing an exact copy. Due to the degeneracy of the genetic code, some
mutations in protein-coding genes are silent, or produce no change in the amino acid sequence
of the protein for which they code; for example, the codons UCU and UUC both code for serine,
so the U↔C mutation has no effect on the protein. Mutations that do have phenotypic effects are
most often neutral or deleterious to the organism, but sometimes they confer benefits to the
organism's fitness.
Mutations propagated to the next generation lead to variations within the population of a species.
Variants of a single gene are known as alleles, and differences in alleles may give rise to
differences in traits. Although it is rare for the variants in a single gene to have clearly
distinguishable phenotypic effects, certain well-defined traits are in fact controlled by single
genetic loci. A gene's most common allele is called the wild type allele, and rare alleles are called
mutants. However, this does not imply that the wild-type allele is the ancestor from which the
mutants are descended.
BIOPHARMACEUTICALS FROM
TRANSGENIC PLANTS
 Glycoproteins can be made (bacteria like E. coli cannot do this)
 Virtually unlimited amounts can be grown in the field rather than in
expensive fermentation tanks
 There is no danger from using mammalian cells and tissue culture
medium that might be contaminated with infectious agents.
 Purification is often easier
Corn is the most popular plant for these purposes,
but tobacco, tomatoes, potatoes, and rice are also
being used.
BIOTECH BASICS
For centuries, humankind has made improvements to crop plants through
selective breeding and hybridization — the controlled pollination of plants.
Traditional plant breeding involves the crossing of hundreds or thousands
of genes, whereas plant biotechnology allows for the transfer of only one or
a few desirable genes. This more precise science allows plant breeders to
develop crops with specific beneficial traits and without undesirable traits.
Many of these beneficial traits in new plant varieties fight plant pests —
that can be devastating. Others provide quality improvements, such as
tastier fruits and vegetables; processing advantages, such as tomatoes
with higher solids content; and nutrition enhancements, such as oil seeds
that produce oils with lower saturated fat content.
Crop improvements like these can help provide an abundant, healthful
food supply and protect our environment for future generations.
PLANT BIOTECHNOLOGY MYTHS & FACTS
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There are no biotech food products currently on the market.
Biotech foods are unsafe to eat.
Biotech foods are not regulated or tested.
Meat, milk and eggs from livestock and poultry fed biotech feed products are not safe.
Organic or conventional crops are more nutritious or safer than biotech crops.
Biotech foods taste different than foods made from conventional crops.
The United States does not require labeling of biotech foods.
Biotech foods and crops have been rejected by consumers.
The United States is the only country growing and consuming biotech crops.
Biotech crops are harmful to monarch butterflies.
Biotechnology is only being applied to a few crop varieties.
The "pipeline" of biotech plants products is dried up - no new products being developed
Biotech crops harm the environment.
Biotech foods can't feed the world.
Biotech crops increase food allergies.
Using biotechnology to improve plants is not natural.
Biotech companies won't disclose where field trials of biotech crops are being grown
Biotech crops harm the environment.
Biotech crops will cause "superweeds" to develop.
The only people who benefit from biotech plants are the agricultural companies
ANIMAL BIOTECHNOLOGY MYTHS & FACTS
 Only humans, not animals can benefit from medical biotechnology.
 Biotech and cloned animals are still years away - science fiction.
 Pets do not benefit from biotechnology at all.
 Biotech and cloned animals are different from normal animals.
 Wild animals cannot benefit from cloning technology.
 Biotech will cause disease outbreaks such as avian flu, mad cow disease and West Nile virus.
 Organ transplants from animals are an unreal fantasy.
 We are just exploiting animals by applying biotechnology to them.
 Meat, milk and egg products from biotech animals are unsafe to eat.
 Biotech animals suffer more pain or distress than conventional animals.
 Cloned animals have higher death rates than conventionally-bred animals.
 Cloned animals are not as healthy as non-cloned animals.
 Animal cloning is not safe.
 If biotech animals or fish escape into the wild, they will endanger wild animals and environment.
 Animals are misused in research.
 The famous cloned sheep Dolly did not lead a full and healthy life.
MYTH: BIOTECH FOODS ARE UNSAFE TO EAT
Fact: The Food and Drug Administration (FDA) has determined that biotech
foods and crops are as safe as their non-biotech counterparts. The American
Medical Association, the American Dietetic Association, and the U.S. National
Academy of Sciences have also declared biotech foods safe for human and
animal consumption. In addition, since being introduced to U.S. markets in
1996, not a single person or animal has become sick from eating biotech
foods.
Other international groups that have concluded biotech foods and crops are
safe are The United Nations Food and Agriculture Organization, the World
Health Organization, the International Council for Science, the French Food
Agency, and the British Medical Association. The European Food Safety
Authority (EFSA) has also found several biotech varieties to be safe for human
and animal consumption.
MYTH: NO BIOTECH FOOD PRODUCTS MARKETED
Fact: 70+% of processed foods on grocery store
shelves contain ingredients and oils from biotech
crops. The first biotech crop, a tomato improved
through biotechnology, was sold in 1994. The
first biotech commodity crops - an insect
resistant variety of corn - were grown and sold in
1996. Today, the most popular biotech crops are
corn, soybean, cotton and canola.
C5 PLUM POX RESISTANT PLUMS
Plums that have been
genetically engineered
to be resistant to the
plum pox virus
TOBACCO MOSAIC VIRUS RESISTANCE
Tomato plants infected
with tobacco mosaic
virus (which attacks
tomato plants as well as
tobacco). The plants in
the back row carry an
introduced gene
conferring resistance to
the virus. The resistant
plants produced three
times as much fruit as
the sensitive plants
(front row) and the same
as control plants.
(Courtesy Monsanto
Company.)
PESTICIDE RESISTANCE
Effect of the herbicide bromoxynil on tobacco plants transformed with a
bacterial gene of which a product breaks down bromoxynil (top row)
and control plants (bottom row). "Spray blank" plants were treated with
the same spray mixture as the others except the bromoxynil was left
out. (Courtesy of Calgene, Davis, CA.)
BT CORN
Bt corn is a variant of maize, genetically
altered to express the bacterial Bt toxin,
which is poisonous to insect pests.
The pest is the European Corn Borer.
BT CORN: CONT’D
 Expressing the toxin achieved by inserting a gene from the lepidoptera pathogen
Bacillus thuringiensis into the corn genome.
This gene codes for a toxin causing the
formation of pores in the larval digestive
tract. These pores allow naturally occurring
enteric bacteria such as E. coli and Enterobacter to enter the hemocoel where they
multiply and cause sepsis (Broderick et al.,
PNAS 2006). Contrary to the common notion
that Bt toxin kills the larvae by starvation.
 Bt176 varieties were voluntarily withdrawn, in 2001, from the list of approved
varieties by the USEPA after finding to have
little or no Bt expression in the ears and not
found to be effective against second
generation corn borers. (Current status of
Bt Corn Hybrids, 2005)
 Effect on non-target invertebrates
depends on the standard of comparison
PREVENTING BT RESISTANCE IN PESTS
 By law, farmers in the United States who plant Bt corn must plant
non-Bt corn nearby. The non-modified fields provide a location to harbor
pests. These refuges slow the evolution of resistance to the pests to the
Bt pesticide. Doing so enables an area of the landscape where wild type
pests will not be immediately killed.
 It is anticipated that resistance to Bt will evolve in the form of a
recessive allele in the pest. Because of this, a pest that gains resistance
will have an incredibly higher fitness than the wild type pest in the Bt
corn fields. If the resistant pest is feeding in the non-Bt corn nearby, the
resistance is neutral and offers no advantage to the pest over any nonresistant pest.
 Ensuring that there are at least some breeding pests nearby that are
not resistant, increases the chance that resistant pests will choose to
mate with a nonresistant one. Since the gene is recessive, all offspring
will be heterozygous, and the offspring from that mating will not be
resistant to Bt and therefore no longer a threat. Using this method
scientists and farmers hope to keep the number of resistant genes very
low, and utilize genetic drift to ensure that any resistance that does
emerge does not spread.
THE EFFECT OF BT CORN ON MONARCHS
 A small, preliminary
study done at Cornell
University, and reported as a
note in Nature in June 1999,
indicated that monarch
butterflies under laboratory
conditions might be harmed
by eating pollen from Bt corn
plants. That experiment
used a small number of
caterpillars and gave them
no choice about avoiding
eating leaves that had been
treated with a thick layer of
Bt corn pollen. It did not
attempt to duplicate real
world environmental
conditions.
THE EFFECT OF BT CORN ON MONARCHS
There is no significant risk to monarch butterflies
from environmental exposure to Bt corn, according to
research conducted by a group of scientists
coordinated by the Agricultural Research Service
(ARS), U.S. Department of Agriculture. This research
was published in the Proceedings of the National
Academy of Sciences (PNAS).he studies in this
project showed that monarch caterpillars have to be
exposed to pollen levels greater than 1,000
grains/cm2 to show toxic effects.
Caterpillars were found to be present on milkweed
during the one to two weeks that pollen is shed by
corn, but corn pollen levels on milkweed leaves were
found to average only about 170 pollen grains/cm2 in
corn fields.
http://www.pnas.org/cgi/content/full/211297698v1
BT COTTON
Saves 3.46 M lb
raw material
- Conserves 1.48
Mgal fuel oil
- Eliminates 2.16
M lb industrial
waste
- Transports
and stores
416,000 gal
insecticide
less
- Conserves
604k gal fuel
oil
- 1.04 million lb insecticide less
2.5 fewer applications per acre
- 416k fewer insecticide
containers
- Saves 41,250 10-h workdays
- Eliminates 2,150 10-h days of
aerial application
- Conserves 2.41 Mgal fuel and
93.7 Mgal water
-Accrues
$168 million
in economic
benefits from
lower
production
costs and
increased
cotton yield
- Reduces pesticide
exposure risk
- Preserves beneficial
insect populations
- Creates wildlife benefits
- Gives cotton producers
more time for family and
community activities
- Gives cotton producers
peace of mind
Produces
fiber
equivalent
to that
found in all
consumer
products
derived
from cotton
GOLDEN RICE
Progress in production of transgenic cereals for developing countries
 Achievement has been the introduction of genes that produce betacarotene – the precursor of vitamin A – in the rice grain.
 Beta-carotene is present in the leaves of the rice plant, but
conventional plant breeding has been unable to put it into the grain.
 Dr. Ingo Potrykus of the Swiss Institute of Plant Sciences in Zurich,
with Rockefeller funding, transferred one bacterial and two daffodil
genes.
 The transgenic rice grain has a light golden-yellow color and
contains sufficient beta-carotene to meet human vitamin A
requirements from rice alone.
 Potrykis has also added a gene from the French bean to rice that
increases its iron content over threefold.
THE STARLINK CORN CONTROVERSY
StarLink variety of Bt corn patented by Aventis (acquired by Bayer AG, 2002), for use in animal feed.
U.S. regulatory authorities permitted StarLink seed but not to be grown for human consumption.
This restriction was based on the possibility of an allergic reaction to the Bt protein used in StarLink.
 StarLink corn was subsequently found in food. Taco Bell taco shells was particularly well publicized 1
 A public relations disaster for Aventis and the biotechnology industry as a whole! Sales of StarLink
seed were discontinued. Aventis voluntarily withdrew the registration for Starlink varieties in 20002
 28 people reported apparent allergic reactions. However, the US Centers for Disease Control studied
the blood of these individuals and concluded there was no evidence of hypersensitivity to Bt protein 3
 5 weeks after the FDA/CDC declared StarLink safe, based on blood tests, advisers to the EPA including some of the leading food allergists, released a thorough critique of the FDA's allergy test and
other aspects of the StarLink investigation. They said the research to declare StarLink safe had many
shortcomings including, lack of adequate controls, not sensitive enough and failed to follow standard
protocols that helped prevent false interpretations. (FIFRA Sci. Advisory Panel Report #2001-09, July ‘01)
 Aid sent by the UN and the US to Central African nations also contained some StarLink corn. The
nations involved refused to accept the aid.
 The southern portion of the U.S. Corn Belt planted the greatest amount of StarLink corn. It is this
portion of the U.S. where corn borer damage creates the greatest economic loss to farmers.
 The US corn supply has been monitored for the presence of the Starlink Bt proteins since 2001. No
positive samples have been found since 2004, showing that it was possible to withdraw this GM crop
without leaving traces in the environment once it has been used in the field 4
ETHANOL CONTRIBUTION TO ENERGY AND ENVIRONMENTAL GOALS
ALEXANDER E. FARRELL, RICHARD J. PLEVIN, BRIAN T. TURNER, ANDREW D. JONES, MICHAEL O'HARE, DANIEL M. KAMMEN
SCIENCE VOL 311 27 JANUARY 2006 www.sciencemag.org
Liquid fuel
Net Fossil Inputs Net Fossil Ratio
MJfossil / MJfuel
Petroleum Input
GHG Emissions
MJfuel produced/MJfossil MJpetroleum /MJfuel g CO2-eq. per MJfuel
Gasoline
1.19
0.84
1.10
94
Ethanol 2005
0.774
1.30
0.04
77*
CO2-intensive EtOH
0.94
1.06
0.18
91*
Cellulosic ethanol
0.10
10.0
0.08
11
http://rael.berkeley.edu/ebamm
GENETICALLY MODIFIED SALMON
The issue has raised questions
about impacts on the environment,
evolution and the future of food.
 Armed with a gene from
the ocean pout -- the new
salmon, which originally hails
from the Atlantic, grows twice
as fast as its less endowed
peers out at sea.
 The Food and Drug
Administration has concluded
that the new salmon is safe
to eat and safe for the
environment, suggesting that
approval is likely at a hearing
planned for later this month.
The decision would make the
fish the first genetically
modified animal allowed for
human consumption.
GENETICALLY MODIFIED SUGAR BEETS
 Roundup resistant
 Challenged in court September, 2010
PROTEINS PRODUCED BY TRANSGENIC CROPS
Human growth hormone with the gene inserted into the
http://images.google.com/imgres?imgurl=http://ol
chloroplast DNA of tobacco plants.
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furl=http://kikoshouse.blogspot.com/2006/03/scie
Humanized antibodies against such infectious agents as
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HIV
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m=1&tbnid=GUU8gNWaI4XS2M:&tbnh=141&tbn
respiratory syncytial virus (RSV)
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sperm (a possible contraceptive)
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herpes simplex virus, HSV, the cause of "cold sores"
Protein antigens to be used in vaccines
An example: patient-specific antilymphoma (a cancer) vaccines. B-cell lymphomas
are clones of malignant B cells expressing on their surface a unique antibody
molecule. Making tobacco plants transgenic for the RNA of the variable (unique)
regions of this antibody enables them to produce the corresponding protein. This
can then be incorporated into a vaccine in the hopes (early trials look promising) of
boosting the patient's immune system — especially the cell-mediated branch — to
combat the cancer.
Other useful proteins like lysozyme and trypsin
AGROBACTERIUM TUMEFACIENS – T-DNA
Invades damaged plant sites
Releases transfer DNA (t-DNA)
T-DNA invades plant cells, is incorporated into the genome
Infected cells grow rapidly to form galls
The infected cells produce food for the bacteria
The invasion is DNA transfer between kingdoms
This is exploited to introduce desirable genes
This produces transgenic plants
Salt tolerant rice
Golden rice
TRANSGENETICS WITH A. TUMEFACIENS
EXPOSURE TO ENGINEERED AGROBACTERIA
REDUCING THE RATE OF INSECT RESISTANCE
DEVELOPMENT
The rate of resistance
development to transgenic
plants can be reduced by
either expressing proteins
with different modes of action,
or binding characteristics in
one plant (gene pyramiding)
or by expressing proteins with
different modes of action or
binding characteristics in
separate plants and then
using these plants either in a
mosaic or sequential fashion
FOOD PRICES
Worldwide food prices have also increased considerably.
But biofuels only consume roughly 4% of the world's grains.
USDA Secretary Schafer stated: last year "Higher oil prices affect much more
than just the cost of driving; they are actually one of the major factors behind
higher food costs."
The USDA and the White House Council of Economic Advisors have stated
that increased corn demand is only responsible for "3 percent of the more
than 40 percent increase we have seen in world food prices this year."
Ethanol is made from "dent" or yellow "feed" corn. People accuse
ethanol of increasing the price of beer, pasta and tortillas, which is
curious because none of those products are made from "dent" corn.
Major food companies are profiting nicely from the food price crisis: Land
O'Lakes (earnings up 16%), Kraft Foods (earnings up 21%), Sara Lee (net
income up 55%), and General Mills (profits up 61% from 2007).
GALLS: MAPLE TREES
Galls on a
maple leaf
GALLS: ROSE
Rose
bedeguar
gall
GALLS: OAK
Oak
artichoke
gall
caused
by a
wasp
GALLS: OAK MARBLE GALLS
Cross-section (above)
Green stage
Oak marble galls,
one with a gall
wasp exit hole
and another with
Phoma gallorum
fungal attack
GALLS: LIME NAIL GALL
Caused
by a mite,
Eriophyes
tiliae, of
0.2 mm
long
BACTERIAL GALLS
Pseudomonas
syringae causes
bacterial gall on
oleander and olive.
... Gall bacteria
reproduce in
fissured or galled
bark and are
spread by ...
BACTERIAL GALLS: ROSE
Agrobacterium
tumefaciens
manages to
survive in the
rhizosphere on
materials that leak
from roots. It
infects wounded
host plant stems
and roots.
FUNGAL GALLS
Fungus stem
gall or "poop
gall" on
choke cherry
(Prunus
virginiana) in
Montana. The
swollen
stems are
caused by the
fungus
Dibotryon
morbosum
GIANT FUNGI AND TREES
1. The mycelium of some forest fungi can
extend enormous distances. A single
individual of Armillaria bulbosa
permeates >30 ac forest soil in northern
Michigan and may be one of the world's
largest living organisms. Some scientists
speculate that it was spawned by a single
spore thousands of years ago. Another
Armillaria in Washington was recently
found to consist of a subterranean
mycelial network with erect, aboveground mushrooms covering > 1000 ac
2. These fungal monstrosities are rivaled in total size and mass by a 106 acre,
6,000 ton stand of genetically identical quaking aspen in the Rocky Mountains.
The aspen clone is connected by a common root system, and has literally climbed
over mountains and across meadows. Any discussion of massive clonal colonies
should also include the conjoined polyps of coral reefs. However, the question still
remains: Do these clonal colonies qualify as a single individual, as in the 1200 ton
General Sherman tree of California's Sequoia National Park?
GIANT FUNGUS: OREGON
Mycologists investigated if
Armillaria could be killing
trees dying in the Malheur
National Forest in the Blue
Mountains of eastern Oregon
and were astonished.
This most recent find was
estimated to cover over
2,200 acres (890 hectares)
and be at least 2,400 years
old, possibly older.