A IDENTITAS
Hari/Tanggal : Jumat / 20 Juli 2012
Waktu :
08.30-11.30
B KEGIATAN
Trans-genetics
C RINGKASAN KEGIATAN
A
transgenic crop plant contains a gene or genes which have been artificially
inserted instead of the plant acquiring them through pollination. The inserted
gene sequence (known as the transgene) may come from another unrelated
plant, or from a completely different species: transgenic Bt corn, for example,
which produces its own insecticide, contains a gene from a bacterium. Plants
containing transgenes are often called genetically modified or GM
crops, although in reality all crops have been genetically modified from
their original wild state by domestication, selection and controlled breeding
over long periods of time.
In 2011,
the global area of biotech crops continued to increase for the 16th year at a
sustained growth rate of 8% or 12 million hectares (30 million acres), reaching
160 million hectares or 395 million acres (Figure 2). Biotech crops have
set a precedent in that the biotech area has grown impressively every single
year for the past 16 years, with almost a remarkable 94-fold increase since
commercialization began in 1996. Thus, biotech crops are considered as the
fastest adopted crop technology in the history of modern agriculture.
In 2011, a total of 16.7 million
farmers planted biotech crops in 29 countries, wherein over 90% or 15 million
(up from 14.4 million in 2010) were small and resource-poor farmers from
developing countries. The highest increase in any country, in absolute
hectarage growth was Brazil with 4.9 million hectares and the highest
proportional increase was Mexico with a 146% increase to reach 175,500 hectares.
Distribution of Biotech Crops in Industrial
and Developing Countries
Figure 3 shows the relative area of biotech
crops in industrial and developing countries from 1996-2011. In 2011, almost
half of the global biotech crop area of 160 million hectares, equivalent to
79.8 million hectares, was grown in 19 developing countries. It is
noteworthy that in 2011, all four countries that exhibited proportional
growth in biotech area of 10% or more were developing countries; they were in
descending order of percentage growth: Mexico (146% increase), Brazil (19%),
India (13%), and China (11%). As in the past, in 2011, percent growth in
biotech crop area continued to be significantly stronger in the developing
countries (11% and 8.2 million hectares) than industrial countries (5% and 3.8
million hectares). Thus, year-on-year growth measured either in absolute
hectares or by percent, was higher in developing countries than industrial
countries between 2010 and 2011.
Transgenic Crops, GM (genetically modified) Crops and
GM foods. The DNA sequences are altered in transgenic
(GM) crops. Insert a foreign
gene/silence a native gene/modify a native gene. GM foods: foods
derived from genetically modified organisms (GMOs)
How about GM food in china
71.5% cotton cultivated in China are transgenic.
China imports 54 million ton soybean each year and 80%
are transgenic.
China will continue to carry out the strategy of
transgene and not cease to develop GM organisms. Currently, the crops were
commercially grown, approved by the National Committee of Safety for Gene
Engineering, and examined by Ministry of Agriculture：
Cotton with Bt, and Bt+CpTI developed
by Chinese Academy of Agricultural Science (CAAS)
Cotton with Bt developed by Monsanto Ltd. USA
Tomato with delay-maturing, and resistance gene to viruses
Pepper with resistance gene to CMV (cucumber mosaic
virus)
Papaya with resistance to circle speck virus
If it is a 5-digit number beginning with an 8, it is
GM
If it is a 4-digit number .
pay
attention!!!
•
beginning with a 4, it is GM
•
beginning with a 5, it is a hybrid.
•
beginning with a 3, it was sprayed with
agrochemicals.
How about cow milk? GM feeds
77% of Americans would be likely to buy products that
had been genetically engineered to resist insect damage, resulting in less use
of pesticides. Nearly two thirds said that they would be likely to purchase
such products even if they had been engineered only to taste better or stay
fresh longer.
How about in UK
No commercial GM crops are grown in UK now. UK agriculture minister Jim Paice told
farmers in January, 2012 that GM crops
could massively help food production, and Labour's shadow environment minister,
Mary Creagh, calling for more money for GM research.
Caroline Spelman, the environment secretary, “ growing
GM crops was likely to be considered as part of the solution to the drought
currently engulfing much of south-east England.” "the principle of GM technology is OK if
used well."
Why use GM food
Many
reason to use GM food, for example:
•
Maintain high yield, especially in
developing countries.
•
Reduce uses of agro-chemicals which cause
pollution.
•
Improve the nutrition quality of foods.
How
to make GM crops?
1.
Choose
desirable trait
2.
Clone
the gene
3.
Engineer
the gene
4.
Transform
gene into plant
1.
Choose
desirable trait
Pest Resistance: Bt crops
§ Bacillus thuringiensis protein is a
delta endotoxin kills corn borers
Herbicide Tolerance: Round Up Ready crops
§ Agrobacterium tumifaciens protein with
resistance to RoundUp herbicide (glyphosate)
2.
Gene
cloning
The key is to identify the critical genes responsible
for the desirable traits from any organisms. From Proteins:
Isolation of proteins, Sequence of amino acids, Auto-synthesis of DNA. PCR cloning of genes from genomic DNA or cDNA from
any organisms (plant, animal, microbes
3.
Gene Sources
The genes may be cloned in the same crop species. For example, a gene was
cloned via map-based approach from one rice cultivar then the gene was
transferred into another rice cultivar. Even if the gene is already inside the genome, we still may make GM crops
over-expressing this gene (more active). The genes from other organisms, like Bt gene.
1. Transform gene into plant
Take plant leaf sample,
break up and develop callus on media. Callus is mass of undifferentiated cells.
Transform using gene gun or other methods. Grow callus on selective media for
transformants, transfer to growth media becomes plant. Other
methods, electroporation, agrobacterium, whiskers. Totipotent property of
plants.
1. Backcross
breeding is the final step in the genetic engineering process, where the
transgenic crop is bred and selected in order to obtain high quality plants
that express the inserted gene in a desired manner.
Types
of Risks about GM
1.
Safety concerns of foreign genes
The
foreign genes
introduced into transgenic crops are often from bacteria and non-food species,
like Bt gene, and their expression is greatly amplified by strong
viral promoters/enhancers. In practice, that means all species interacting with
the crop-plants - from decomposers and earthworms in the soil to insects, small
mammals, birds and human beings - will be exposed to large quantities of
proteins new to their physiology. Adverse reactions may occur in all species,
including immunological or allergic responses.
Herbicide-tolerance and insecticidal
transgenic plants now almost account
for 71% and 28% respectively of all transgenic crops in the world. These traits
are associated with genes isolated from soil bacteria. The insecticidal Bt-toxins, isolated from Bacillus
thuringiensis, are often engineered into plants in a pre-activated
form, and are already known to be harmful to bees directly, and to lacewings
further up the food-chain.
2. Safety concerns of random unpredictability
The special safety concerns of unpredictability come
both from the random, uncontrollable insertion of foreign genes into the host
genome , and from the unpredictable interaction of foreign genes with host
genes.
Furthermore, T-DNA can be inserted in a truncated or
rearranged form, in single copies or tandem repeats at one or more sites,
perhaps reflecting the instability of the gene constructs; and insertion
mutagenesis is relatively common. The
inserted DNA may also influence other genes downstream or up-stream of it.
3.
Safety concerns of gene constructs
Foreign genes are typically introduced as 'gene
expression cassettes' each with a strong viral promoter/enhancer accompanying a
gene. One viral promoter used in practically all transgenic plants is from the
cauliflower mosaic virus (CaMV), which is closely related to human hepatitis B
virus, and less closely, to retroviruses such as the AIDS virus. The CaMV
promoter may drive the synthesis of related viruses. It is functional in most
plants, in yeast, insects and E. coli.
4. Safety concerns from the uncontrollable spread of
trans-genes and marker genes
Genes can spread from transgenic plants by ordinary
cross-pollination to non-transgenic plants of the same species or related
species, and also by secondary horizontal gene transfer to unrelated species.
The most obvious effects of cross-pollination already identified are in
creating herbicide-tolerant weeds and superweeds. Another special risk is the
spread of antibiotic resistance marker
genes which are in a high proportion of transgenic plants. It is possible that
antibiotic genes enter into food chain, or spread to other organisms. (bacteria
is resistant to antibiotics?) Now this problem was well solved. So-called
marker-free transformation.
5.
Backcross
GM plant into high yield crops
