Past and Present: Improving Plants Through Genetics and Biotechnology

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Past and Present Improving Plants Through
Genetics and Biotechnology

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A Fundamental Truth Photosynthesis by plants is
the source of energy for life on earth
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Humans use approximately 20-35 of all the
photosynthate (food) produced on earth
Plus a large share of the photosynthate produced
in the past few billion years
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What can a plant do with the food it produces
through photosynthesis?

• Use it for its own energy
• Store it in an unusable form
• Store it in a usable form
• (wheat, rice, corn)

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Domestication of Plants save seed from the best
plants to replant next year
W I L D
C R O P
Seed shatters Seed are dormant Small seed Seed
mature at different times
Seed stays on the plant Seed are not
dormant Large seed Seed mature at the same time
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Wheat
Corn
Rice
Potatoes
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Wheat, maize (corn), rice and potatoes are over ½
of all calories consumed by people
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Major Strategy Remove native vegetation and plant
wheat, rice, or corn
Recent Past Today
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Second Era in Plant ImprovementPlant Breeding
Principle Traits are controlled by genes Genes
are inherited in a predictable manner
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Big Advances in Plant BreedingHybrid corn and
semidwarf wheat are used throughout the world
Hybrid Corn Semidwarf Wheat
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Most Plant Breeding Problems are Specific to
Geographical Areas Montana Wheat Stem sawfly
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Little Advances in Plant Breeding
Choteau Spring Wheat High Yield, High Protein,
Solid Stems Parent One Solid Stem, Moderate
Yield Parent Two Hollow Stem, High Yield
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Progeny lines derived from a cross between two
wheat varieties
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Yield Averages and Leading Varieties in Montana
ERA YIELD (b/a) VARIETY 30s 8.9
Marquis 40s 15.3 Thatcher 50s 16.5 That
cher 60s 20.0 Thatcher/Fortuna 70s 23.9 Fo
rtuna 80s 22.9 Newana 90s 30.1 McNeal
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Yield Trial Comparing New and Old Varieties
Bozeman 1999
Variety Year of Release Yield (b/a) Rank Scholar
1999 72 1 McNeal 1996 71 2 Reeder 1998
71 3 Newana 1977 64 10 Thatcher 1934 52
25 Marquis 1911 47 49
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Modern TechnologyMarker-Assisted Selection

• Many genes are difficult to select for using
  conventional methods
• Identification of markers associated with the
  important genes enhances the efficiency and speed
  of selection

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Backcross Breeding Crossing a Single Gene into a
Superior Variety
Recurrent Parent X Donor Parent (hollow, high
yield) (solid, low yield) F1 Hybrid
X Recurrent Parent BC1 X Recurrent
Parent BC2 X Recurrent Parent ETC.
Select for Desired Gene from the Donor Parent
Using Markers
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Mutagenesis to Develop Herbicide Resistant
Crops Soak seed in a chemical mutagen Germinate
seed and spray plants with herbicide Select the
resistant type Successful for developing
Clearfield technology (Resistance to
imidazolinone herbicides)
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Imidazolinone herbicide resistance
Critical Enzyme Made in Normal Plants
Altered enzyme made in imi-resistant wheat
Imidazolinone Herbicide
Imi-herbicide does not inactivate the
enzyme Plant lives
Imi-herbicide inactivates the enzyme Plant dies
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Spring wheat lines derived from imi-resistant by
MT-adapted wheat crosses Bozeman 2007
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CLEARFIELD Winter Wheat
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Traditional Plant Breeding Two individuals must
be able to have sex to transfer genes
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Genes are made of DNA People Wheat Watermelon Bac
teria Cat All Life
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Basic Principle There is no reason that genes
from any species on earth will not function in a
plant.
Challenge Removing a gene of interest from
foreign species and inserting this gene into a
plant chromosome
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The Work-horse for Plant Genetic Engineering is a
Bacteria called Agrobacterium tumefaciens
Agrobacterium inserts a piece of DNA into the
plant chromosome to cause the disease
Crown gall disease
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Scientists can place a gene of interest inside
the Agro DNA then allow Agro to transfer the
gene-of-interest into a plant cell. Then,
regenerate a plant from the cell and a
transgenic plant (gmo) is produced.
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In Nature
The bacteria Bacillus thurengiensis (B-t) has a
gene that produces a toxin that kills certain
insects
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Insect Resistance
Background Cotton growers need 5-6 pesticide
applications to control the cotton
bollworm Observation A bacteria (B-t) has a
gene that makes a toxin that kills
insects Idea Put the gene into cotton to kill the
bollworm
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Bt cotton(Its in our jeans)

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Herbicide Resistance
Background Round-Up kills plants by inactivating
an essential plant protein Observation A certain
bacteria has a gene that produces the same
protein, but this protein is not inactivated by
Round-Up Idea Put this gene into crop plants
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Success Story Herbicide Resistance
Soybeans, corn, cotton, wheat?
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there has never been an agricultural
technology adapted as rapidly as plant
biotechnology
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Observation Wheat is the leading crop in the
world Issue Wheat was a technical challenge for
biotechnology Potential Herbicide
resistance Insect resistance Disease
resistance End-use quality Drought tolerance
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First Wheat Biotechnology Product Round-Up Ready
Wheat
Basic Idea Plant wheat in the spring. Wheat and
weeds emerge. Spray Round-Up. Kill the weeds
while not hurting the wheat. Joint Research
Venture Monsanto Owns right to the Round-Up
Ready gene Breeding programs Own the varieties
adapted to their specific areas
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Issues with Round-Up Ready Wheat (raised by
various stakeholders) University researchers will
be tainted by working with private industry (esp.
Monsanto) Monsanto will have too much control
over farming and farmers Asian wheat buyers do
not want genetically engineered wheat Genetically
engineered wheat (gmo) will contaminate non-gmo
wheat Volunteer Round-Up Ready wheat will make
chem fallow operations impractical
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Round-Up Ready Wheat for Montana Status
Round-Up Ready versions of McNeal and other
varieties are being tested Timeline for
Release Earliest date is 2005 likely date
unknown Never?
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Climate change impacts on Montana spring
wheat? Spring and winter yield in Montana (bu/ac)
Decade Winter Spring 1950s 23 17 1960s 26
20 1970s 29 24 1980s 30 23 1990s 37 30 20
00s 35 25 winter wheat yielded 17 and 15
bu/ac more than spring wheat in 2006 and 2007,
respectively.
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Montana Spring Wheat Production
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Approaches to Developing HeatTolerant Spring
Wheat Cultural Grow winter wheat Plant spring
wheat earlier Heat tolerant varieties Early
heading Long stay-green Others?
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Breeding programs interact with other
disciplines Work with agronomists is needed to
answer the question Will early planting result
in early heading? Daylength sensitive varieties
(McNeal, Outlook) long days are required to
initiate heading Daylength insensitive
varieties (Reeder, Vida) Heading is independent
of daylength