Genetically Modifying Crops to Increase Water Use Efficiency (WUE) and Resistance to Water Deficient Conditions

A Guide to the Economic, Political and Social Impacts of a Scientific Revolution

Topic Background: Genetically Modified Crops and their Development: How, When, Where and Why?

Brief Overview:

Geneticists have sought to comprehend the ways information encoded in an organism's genetic makeup (genes) determine the organism's cellular structure and how variations in these genes can lead to developmental disorders or diseases. Modern Genetics have developed techniques to alter the genetic makeup of and to direct the growth of an organism.

Agriculture, along with other fields of research such as medicine, has served as the testing ground for such alterations focused on making more sustainable plant species that have been genetically modified to withstand pests, climatic conditions and unsuitable environments of pH or salt concentrations. (Citation 1)

Though such advancements in technology result in increased crop yields, the potential for abuse of genetic enhancement techniques has led to increased debates and controversies (1) over the ethical and legal issues concerning monopolistic empires' acquirement of patents over certain parts of the genetic code of organisms and human imitation of God.

Anti- GMO Propoganda, International Day of Farmer's Struggle Against GMOs and Patents on Life is observed on April 17th

1.1 Anti- G.M.O. Propaganda and Rallies- International Day of Farmer's Struggle Against G.M.O.s and Patents on Life is observed on April 17th

 1.2(a): X-ray diffraction photo of a DNA molecule (left)

1.2(b): The original DNA model by Watson and Crick (right)

Scientific Advent:

Chemical studies in the late 1940's by E. Chargaff that indicated amine base pairing in the DNA structure (Adenine-Thymine and Guanine-Cytosine) combined with the experimental results using X-ray diffraction, analysis of bending light waves (see Image 1.2a- left), employed by Rosalind Franklin and Maurice Wilkins, portrayed the physical structure of the DNA molecule and set grounds for Watson and Crick's publication in 1953. Such discoveries initiated the emergence of a new field of genetic engineering and new techniques for isolating, sequencing and replicating the DNA molecule in the mid-20th Century.  (Citations 2,3)

The proposed structure of the DNA double helix (see Image 1.2b- left) can be seen as a twisted ladder. The sides of the ladder are composed of alternating sequences of deoxyribose and phosphate. The rungs of the ladder are formed by amine base pairing (joined by hydrogen bonds). The hydrogen bonding susceptible to breakage under high temperatures leads to denaturing of DNA molecules. Knowledge of how genetic material is stored and copied in organisms and the fact that all organisms share the same building blocks of A's, T's, C's and G's led to the development of manipulation techniques that would allow for pieces of DNA to be cut and inserted from and into an organism's genetic code. The organism then exhibits the trait coded for by the gene sequence through transcription and translation of its DNA. (2,3)

Progress Through Restriction Enzymes:

Werner Arber, a Swiss molecular biologist during the 1960's and 70's, discovered specialized enzymes present in bacteria that digest, and thereby restrict, the viral DNA from seizing control of the bacteria's cellular functions. Genetics expanded in a direction towards employment of such restriction enzymes for cleaving DNA molecules at precise (Therefore predictable) nucleotide sequences.

Further developments on Arber's experiment have led to the creation of DNA molecules from 2 different sources (Herb Boyer, 1973- US). The splicing of these strands of DNA to create a hybrid is now known as the creation of Recombinant DNA. Through this technique, foreign genes can be introduced to the DNA of a plasmid or virus. (Citation 1,11)

Important Terms to Know:

Restriction Enzymes: Specialized enzymes that cut the phosphate backbones of DNA molecules at specific base sequences. The strands generated by restriction enzymes have "Sticky" ends and are single stranded and can therefore easily bind with other DNA fragments as long as the amine base pairs correspond.

Recombinant DNA: DNA that has been generated artificially through the combination of portions of DNA strands from different species. 

Vector: a DNA molecule used as a vehicle for transferring genetic material from a foreign organism (examples: bacterial plasmids or viruses)

Viral Transformation: introduction of foreign DNA into a host cell using a viral vector

Bacteria as a vector: (example- Agrobacterium) bacteria that causes diseases in plants and is able to transfer fraction of its DNA into the plant cell. 

(Citations 4,5)

Transgenic Manipulation employs several different concepts, click below to skip to an interactive application (Citation 5)

1.4: Overview of creation of Transgenic Crops 

Genetic Engineering and Advancement toward GMO's:

Genetic Engineering techniques alter the phenotype/function of an organism by allowing insertion of advantageous genes from one organism to another.

Restriction enzymes are used to isolate a segment of DNA that contains a gene of interest present in the organism's cell.
If two pieces of DNA are treated with the same restriction enzymes, they bind together to form a hybrid (The restricted DNA from a vector binds with the restricted DNA fragment from the foreign organism) that is then transformed into the targeted species through viral or bacterial transformation. Once the strand of recombinant DNA is inserted into the plant cell, the DNA is incorporated into the DNA of one of the plant's chromosomes. The transformed cells of the targeted plant are then grown to produce a transgenic crop that exhibits the desired trait.

The altered genetic makeup of the transgenic plant enables it to grow in previously unsuitable conditions.

(Citations 1,6,8)


 Topic Background: Modification of Traditional Techniques

Gene Guns:

Introduced roughly 15 years after the advent of Transgenic Manipulation which used viruses and agrobacterium as vectors for introducing new genetic material into plant cells, the Gene Gun was designed by John Sanford in 1987 at Cornell University as a solution for the low transformation efficiencies of viral and bacterial transformations.

The biolistic method is an advanced technique of genetic engineering in which a special gun is used to implant DNA-coated metal pellets in target cells to effectively introduce the trans-gene and allow for expression of the desired trait. 

The significance of this improvement on traditional transformation techniques lies in the ability to target particular organelles. Foreign DNA can now be inserted into chloroplasts to engineer genes specific to such organelles and thereby make a plant more suitable to an environment due to a genetic advantage.

Animation: Developed by Plant & Soil Sciences eLibraryPRO

(Citations 8,9)

Topic Background: Challenges to Research and Advancement

Concerns over Labeling:

Customer surveys conducted by the USDA, the United States Department of Agriculture, suggest that there are concerns over the ingredients and chemical compounds present in genetically enhanced food crops. Though GM crop producing companies and manufacturing plants would not be directly economically impacted by labeling their products as GMO, the lack of evidence behind health betterment by intake of GM food could deter consumers. Anti-GMO protestors argue that the higher yield produced by GM seeds does not supersede the potential harms to human health, the environment and traditional farming techniques. Large scale companies are faced with continuous public opposition but continue to reiterate that GM foods provide means of production in environmental conditions where food would not have been farmed before and therefore helps feed the growing global population.

Law Suits and Opposition to Patenting:

Lawsuits filed in March 2011 have sought to invalidate large scale corporations' patents on GM seeds. Critics of the Genetically Enhanced Revolution claim that the GMO market has developed into a venture exclusive to large scale entrepreneurship and monopolistic control. Lobbying efforts in the US Congress by large scale companies  are blamed by anti-GMO activists for restriction of independent research. Independent researchers seek to experiment with GM seeds to test for harmful effects to health and the environment. Growing opposition also argues that tactics of "Double-Patenting", claims to enhancements and improvements, lead to increased monopolistic growth and therefore restrict establishment of new business.

In light of GM food opposition, fears over contamination through escape of genetic attributes to surrounding plant species, and increased monopolistic growth, the GM food industry struggles publicly to promote acceptance of its technology in the 21st century. (Citation 10)

 Read/Watch more: Ethics and Society

1.7: The Monsanto Company's website urges to Increase Awareness of the Requirement of GM crops while Farmers Protests against Prevalence of Genetically Enhanced crops in the US (>70% of Corn) 

Topic Background: Scientific Ambitions and Areas of Growth

The Facts:

Climate change over the past decades has impacted the global hydrological cycle resulting in varying patterns of water availability for agriculture. According to the FAO (The Food and Agricultural Organization of the UN), agriculture is the single most dominant user of freshwater. This key dependence on groundwater underscores the detrimental effects of drought conditions. Decreasing levels of available water pose threats to the global food production that must feed 9 billion people by 2050. 

(Citations 12,13)

Scientific progress with the success of GM crops over the past 15 years of field employment has paved the way for advancement towards drought-resistant crops that will aid the production of food in areas of scarce water-availability.

The Science:

Drought conditions cause plants to produce a stress hormone called Abscisic Acid which activates a set of protein molecules called receptors. In turn, these receptors are responsible for closing the guard cells on the inside of leaves in order to lower the rate of evapotranspirtation, the upward movement of water through a plant. This chain of reactions prevents loss of precious water needed during times of drought; in this way,crops that respond to ABA effectively are Water Use Efficient (WUE) crops.

Researchers at UC Riverside have been successfully in engineering Abscisic Acid (ABA) receptors that can remain permanently active. Various genetically engineered receptors were tested to discover the chain of chemical reactions that would "Supercharge" the reaction. Though field testing will continue for the upcoming years, progress in this direction suggests global reliance on GM crops in the decades to come.

Additionally, newer systems for analysis of genetic markers (DNA sequences with a known location on a chromosome) in rice plants allow for generation of genetic Fingerprints (an organism's genetic makeup) that would help identify nearby genes linked to specific desirable traits in the future.

(Citation 14,15)  

 1.9: Charged ABA that is not absorbed by the Mesophyll during Dry conditions is able to reach the Stomata, scientists are working to produce GM crops with ABA always charged to increase resistance to Drought-type conditions


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