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Genetics can be applied to agriculture
in three main ways:
1.
To increase productivity,
2. To control
disease, weeds, and insects that harm plants, and
3. To preserve
genetic diversity withing the ecosystem.
The current focus of agricultural
biotechnology lies in developing herbicide tolerant
crops as well as pest/disease resistant crops.
In 1981, new technology made genetic engineering more
feasible with the creation of the “gene machine”.
Gene splicing could be done using polymucleotide assembly
machines (machines that make DNA by assembling base
pair sequences) that made chains of genetic fragments
to lengths determined byprogrammers. These “gene machines”
add one nucleotide after another onto the deoxyribose
backbone in the order specified. This allowed scientists
to find, cut and reassemble genes, and change the
order of the genetic messages.
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Later that decade,this invention enabled
American researchers to transfer a gene from
a French bean seed into a sunflower cell. The
gene was spliced into a bacterium that would
normally infect the sunflower cell; instead
of infecting the cell, though, the recombinant
DNA that replaced the disease genes simply created
a “sun bean” plant, a food extremely rich in
protein. Using this and similar methods, plants
can be altered to provide more and healthier
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Fertilization
Crops use tremendous amounts of nitrogen-based
fertilizers each year to increase production yields.
Unfortunately, these fertilizers pollute streams
and ground water, and many are seeking alternative
methods of fertilizing. Plants absorb the nitrogen
fertilizers when it is changed to ammonia by "nitrogen-fixing"
bacteria in the soil. Scientists at Cornell University
have isolated a group of genes in these "nitrogen-fixers"
and spliced them into yeast cells. This allows the
plants to utilize nitrogen themselves, without the
use of the fertilizers.
Pesticides
There is a heavy mandate in the U.S.
to develop alternatives to chemical pesticides for
controlling agricultural pests. Studies have shown
chemical pesticides can cause significant health
risks to humans, contaminate water supplies, and
harm non-target life. One solution involves genetically
enhancing plants to combat pests directly. Plants
can be grown without chemicals and with increased
resistance to disease and pests using genetic engineering.
Sugar beets, for example, are very susceptible to
a variety of worms, whereas other types of beets
are not because of a protein they naturally produce.
Genetic engineers can take the gene from the worm-resistant
beets and insert it into the DNA of the sugar beet.
The engineered sugar beet is no longer at the mercy
of the worm, and the environment isn't harmed.
Other problems exist. Some commercial
pesticides have been withdrawn from the marked because
of health and environmental risks, leaving many
crops vulnerable to disease and insects. Several
varieties of pests are becoming pesticide-resistant,
rendering the chemicals useless. At Cornell University,
the Bioprocess Development Research project is attempting
to discover new natural products which provide safer
means of pest control using biopesticides (natural
pesticides as opposed to manmade) from fungi and
other plants.
Insects
Other Cornell researchers are studying
insects' infestation at the molecular level to determine
the mechanism for causing the infection. Then they
develop molecular means to control the pest. Cornell
maintains the world’s largest collection of cultures
for fungal diseases caused by insects, mites, spiders,
nematodes (worms) and other invertebrates. This
collection is kept submersed in liquid nitrogen.
The university’s Plant Virology Study
examines virus development. Cornell scientists are
studying how insects transmit viruses and the role
of plant resistance in disease control. They are
trying to understand the cellular and molecular
mechanisms that determine transmission of a virus.
Currently they’re studying a virus which comes from
a species of aphids. Their hypothesis is that the
virus is transmitted when interaction occurs between
the virus’ capsis protein and the membranes of the
aphid’s salivary gland. The research goal is to
develop methods to screen germplasm, the protoplasm
of germ cells containing the chromosomes, for resistance
to the virus.
Potatoes
Cornell University scientists working
on the Plant Nematology Research Project are developing
nematode-resistant (worm resistant) potatoes. They
are trying to explore microbes as natural controls
of plant nematodes. They use DNA-based procedures
to study genetic and pathogenic variations in nematodes.
They have identified a place of resistance to the
nematodes in the potato chromosome and are incorporating
it into adapted potato germplasm. Currently they
are trying to develop this germplasm in commercial
cultivars.
Grains
Genetic technology is being used
to grow bigger and better oat crops. Researchers
at Cornell University are mapping the genes of oat
DNA for specific traits. Once the oat genome has
been mapped and identified, scientists can identify
superior alleles based on DNA sequence.
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