Using Genetics To Increase Crop Yields Biology Essay

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The demand for food production increase from day to day as ever-increasing human population. However, the yield of agriculture is limited as our earth does not have enough soil and food crops always damaged because of nature like insects. As an example, in corn plants, it is estimated that seven percent or 40 million tons of corn are unmarketable due to insect damage (Novartis, 2000). The farmers copes the insects problem by using pesticide. But, not all people agree with the uses of pesticide as it gives many negative effects such as algae blooming and affects human healthy.

As a result, the scientists try to find the way to increase the crop yield without insect damage and high pesticide use. With understanding of genetics and the availability of advanced technologies, they have find solution to maintain the high yields demanded of our food crops. They done it based on knowledge about genetic modification and have produced transgenic plant or genetically-modified (GM) plants. Wikipedia state that the meaning of transgenic plant is the plants possess a single or multiple genes which are transferred from a different species as DNA from another species can be integrated into a plants' genome via natural processes, whereby, the term "transgenic plants" refers to plants created using recombinant DNA technology in a lab.

The goodness of transgenic plants is they can be created with exact desired trait such as increase resistance or improve the nutrients accurately and rapidly through DNA modification. The genes that will be inserted to the new plant not only can be from the plants, but from non-plant organism also. One of the examples of GM plant is Bt corn. It is made up by inserted Bt gene into the corn. Bt gene or Bacillus thuringiensis is a naturally occurring bacteria that produce crystal protein. This crystal protein is lethal to insect larvae results the corn enables to produce its own pesticide against inserts such as the European corn borer (Whitman, D.B, 2000). Bt genes play its role by rupture the intestine of corn borer and related organisms when it is ingested and this damages the cell membrane, making it leaky, and stopping the larva in tracks. The pests normally die within two to three day.


Timeline of Bt Corn




Shigaten Ishiwatarie

Bt or B. thuringines is discovered by a him, a Japanese biologist

He investigate the cause of sotto disease (sudden collapse disease) that was killing large populations of silk worms


Ernst Berliner

He rediscovered Bt when he had isolated a bacterium that killed a Mediterranean flour mouth.

He mentioned the existence of protein crystal but the activity of the crystals was not discovered until much later.


Farmers using pesticide to kill moth larvae, since that was the only strain that was known that time.


At France country

Bt bacteria was grown in large quantities and sprayed on corn crops to prevent ECB damage [1] .

Artificial selection of Bt strains has lead to successful of many insect pests.


Fitz-James Hannay and Angus Hannay

They discovered that the reason Bt killed the mouths was due to the protein crystal.

Hence, the research on Bt and Bt crystal had begun.


After discovered, there were 13 different of strains of Bt that only effective against moth was found

However, the first strains are toxic to the flies


The next strain was found.

Against it was toxic to others animal, beetles


EPA registers the first genetically modified Bt corn.


Environmental Protection Agency ( EPA) approved the first corn seed variety engineered with a gene from a Bt bacterium as a safe pesticide under Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA)


Public and private researchers began studies to explore whether Bt corn pollen truly affects monarchs in their natural habitat.

Note appears in Nature magazine claiming that transgenic corn pollen harms monarch caterpillars, Losey et al.


Scientifically reviewed paper is published showing the absence of toxicity of Bacillus thuringiensis pollen to black swallowtails under field conditions, Wraight et al

1996 -


EPA registered a dozen different kinds of corn with BT genes that provide corn-borer protection, corn-rootworm protection or both.


Bt corn is made up by inserting Bt genes derived from Bt bacteria (Bacillus thuringiensis) in corn plant. Bt bacteria store multiples toxin proteins. The individual toxin genes has been isolated and cloned, each of them is differ in the range of insect that each poison. The main crystal toxin is Cry1. Each toxin that modifies crop is usually modified in its DNA sequence by introduction of regulatory sequences such as introns, polyA signals, promoters, termination, marker genes and enhancers. (Promoter is needed to determine where the genes express in trait; termination is essential to identify the end of modified genes; marker genes are required to identify modified genes once it has been incorporated in plants). Varieties that express toxin in kernels tend to longer season protection than varieties that express only in the pollen and green tissue. The DNA and protein sequences are altered to make the gene more active in the crop and the toxin more soluble in plants. Cry-transformed corn varieties (BT corn), produce sufficient levels of Cry proteins to provide an effective measure of resistance against ECB. The steps of making Bt corn is shown in diagram below:

Steps of Making Bt Corn

General schematic of GM crop production (Bt Corn)


Positive Effects

Yield production increase

# Corns get nearly season long-protection from European corn borer.

# Reduce yield loss and harvest lost.

# Increase profit margins through more efficient and corn production. In the same time, consumers get benefits as the grocery bill reduced.

Lower the use of insecticide

# The uses for pesticide for Bt corn drop 90 percent annually and save 7000,000 pounds of insecticide per year.

# Decrease chemical leaching into sources of water like well and waterways. So, human and others animal get less exposure to potentially harmful chemical.

Safe for all organisms

# Improve working environment for farmer through less exposure to pesticides

# Bt proteins are not toxic to people, domestic animals, fish, or wildlife. They have no impacts on the environment as they are highly selective in killing larvae of moths.

# Bt corn does not cause food poising to humans because it contains a plasmid that produces the certain protein crystals which are toxic to insect only. 

Decrease the others disease that associated to the corn

Direct impacts of Bt corn on beneficial insect have not been observed till now.


The insects such as European Corn Borer (ECB) may develop resistance to Bt crystal protein in corn

# Insects have ability to rapidly develop resistance to certain insecticides.

Harm to other organisms

# Cause high mortality rates in monarch butterfly caterpillars. This animal only consumes milkweed plants not corn. People assume that the caterpillar eat milkweed plant that contain pollen blown by wind. However, there is no agreement about this case and need further study.

Economic value

# Bt corn needs cost since insurance is essential because no predictive tool exist to pinpoint either Bt corn will be advantageous its effectiveness against ECB is also varies

# Based on assumptions through market acceptance, continue risk of ECB infestation will increase corn price

# Economic benefits every year and in every field may not be seen

Rise effects on human health

# May cause allerginicity. It happens as a gene is introduced into a plant and cause allergic reaction in certain individual

# May cause others long term effects that dangerous to human health

Genes transfer to non-target species.

# Crop engineered plant may undergo cross-breed with weeds resulting resistance genes in the crop transferred into weeds. This "superweeds" would then be the crop engineered plant as well


Genetically-modified foods (GM foods) have been produced through the advance technology of genetic engineering. It is one of solution for the world to solve hunger and malnutrition problems. In the same time it also helps protect and preserve environment by reducing the uses of pesticides. One example of GM food is Bt corn which can survive better although within existence of European Corn Borer (ECB). However there are many challenges ahead for government and scientist to research more about safety testing, regulations, international policy and food labeling. It is ultimately the responsibility for public, scientist and government to ensure that this powerful technology properly managed in the context of pest management methods, hence it is safe for people, others organisms and environment.