Using advanced techniques in the field of genetic engineering the genetically modified organism is developed. These GM crops have various advantages with respect to insect resistance and nutrition benefits. This report is about these genetically modified foods which are available in the worldwide food market and some of the most common methods to identify them. But still, there are many kinds of researches going on to develop new GMO detection methods.
Genetically modified organism, herbicide tolerance, detection methods.
What is genetic modification?
Most organisms inherit information from their parents via chromosomes that are partially made up of deoxyribonucleic acid (DNA). Sections of this DNA are called genes. With plants, genetic modification (GM) alters DNA by inserting new genes in a ‘gene cassette’ to alter how a plant functions. The inserted material can consist of genes and genetic information from bacteria, viruses, plants and animals or be synthetic or chimeric genes that have never existed before. The two main ways to insert this material into a plant cell are
1) To use a bacterium to ‘infect’
2) To use particle bombardment to ‘shoot’ the GM material into the existing DNA of the host plant. This is different to traditional crossbreeding, which has been used for thousands of years.
There are 3 main types of GM food technique
1. Inserting genes (Gene Shifting): Genes are determined by different DNA sequences, when the isolated gene is inserted into a plant, it becomes part of the plant’s gene and works with its own function. This method can increase or improve the plant such as resistance to insects, which increases the yield of food afterwards.
2. Removing genes (Gene Silencing): The function is reduced or stopped through genetic modification e.g. the function of virus which causes dried and spot of tomato is reduced by removing parts of the gene, thus the virus cannot be reproduced and tomato can grow healthily.
3. Changing the process of catabolism (Gene splicing): Food can be enhanced by changing the process of catabolism, such as controlling the percentage of starch of glutinous rice, and it also includes controlling the taste, mass, colour, and usefulness of food.
Process involved in the development of GM crops 2
1) Isolation of the gene(s) of interest
2) Insertion of the gene(s) into a transfer vector
3) Plant transformation
4) Selection of the modified plant cells
5) Regeneration into whole plants via tissue culture
6) Verification of transformation and characterization of the inserted DNA fragment
7) Testing of plant performance and
8) Safety assessment
Genetically Modified crops currently available in market
With regards to hereditary change of plants, the soybean at first rings a bell. GM soybean is a standout amongst the most generally planted hereditarily changed plants on the planet today. The GM soybean, generally called as the Roundup Ready (RR) soybean, was created by the biotech mammoth Monsanto and made it economically accessible to agriculturists in 1996. It was created to influence the plant to survive being showered on with the non-specific herbicide, Roundup, which can kill traditional soybean plants. The GM soybean from Monsanto was changed by injecting a gene copy from the Agrobacterium sp. strain CP4. Traditional soybean has a comparable gene in its DNA yet is delicate to glyphosate, the dynamic element of the herbicide Roundup. With the inclusion of the CP4 form of the gene, the GM soybean could create protection from the Roundup herbicide. These GM soybeans have resistant to pests, disease and are herbicides tolerant. 6
Corn (field & sweet)
The Bt delta endotoxin was chosen since it is profoundly compelling at controlling Lepidoptera larvae, caterpillars. It is amid the larval stage when the majority of the harm by European corn borer happens. The protein is exceptionally particular, and not harming other insects like bugs, flies, honey bees and wasps. GMOs that have the Bt gene are great with normal control programs since they hurt the predators and parasitoids essentially with less expense than insecticides. They are toxic to insects but are not harmful to humans. Bt has been accessible as a business microbial insecticide since the 1960s and is sold under many names. These items have an amazing record with respect to safety and can be utilized on many yields until the harvest day. 7
Bt Cotton was one of the first genetically modified crops that was produced by the US-based agrochemical multinational Monsanto, and transgenic Bollgard (Bt). Cotton which is resistant to insects was introduced in the year 1996. It is called as Bt cotton since it contains a gene acquired from bacillusthuringiensis (Bt). This gene delivers an insecticidal protein (Cry1Ac) which shields them against bollworm (A. lepidoptora), a major threat to cotton. This worm feeds on the cotton plant leaves and as a result of Bt injection, they make these worms less active, in this way making the plant less harm. As a result of this, the plant resistance to pest increase which helps them to increase the yield by reducing usage of pesticides altogether reducing the overall cost. So this turned into an alternative to normal cotton varieties. 9
Indeed, there are numerous ways. A standout amongst the most well-known, and exemplary, is utilizing Agrobacterium tumefaciens. This microbe has the exceptional capacity to take a specific piece of its DNA (TI plasmid) and embed it into plants, and have access to the nucleus. It doesn’t work on each species or family, yet it deals with many, including Solanum (which incorporates tomatoes and potatoes). Whenever utilized, it is connected basically to female conceptive cells, enabling the plants to pass it onto the generation to come. The most renowned way is presumably utilizing a “gene gun,” which additionally prompts a consolidation of the additional DNA. 8
Figure 1: Creation of insect resistant tomato 8
Glyphosate is a wide range herbicide, which kills grasses and weeds. Plants which contains this glyphosate can’t produce amino acids and will die.Roundup ready canola is the first of its kind which has two different genes. These genes are injected into the canola genome. One is a gene is from the normal soil bacterium called Agrobacterium strain CP4, that can encode the EPSPS enzymes. While the other gene is derived from Ochrobactrum anthropi strain LBAA, which encodes enzyme glyphosate oxidase (GOX). The CP4 EPSPS enzyme has high resilience towards glyphosate, so even if the plant contains glyphosate they can still produce aromatic amino acids. GOX helps to separate the glyphosate inside the plant. 12
Like all plants, papaya is affected by papaya ring spot virus (PRSV) also called ring spot virus, a strong disease which brings down the yield. The University of Hawaii created a resistant to ring spot virus. Specific viral genes encoding capsid proteins were exchanged to the papaya genome. These ring spot virus resistant papaya were grown in Hawaii in 1999. 10
Golden rice is an assortment of rice created through the hereditary adjustment to its biosynthesize. The Beta-carotene (pro-vitamin) is inserted into the rice (endosperm) to create this golden rice. They are made by fusing rice with two beta carotene genes:
• Psy (Phytoene synthase)
• Lyc or ctr1 (lycopene cyclase) 11
Detection of GM crops and products
In general the procedure consists of three distinct steps
1) Detection: The main idea is to check whether the product is GM or Non-GM. Usually this is done by screening methods based on PCR, immunoassays or bioassays which will provide a positive or negative result.
2) Identification: The objective of identification is to find out whether the GM crop or products produced are authorized or unauthorized in the country.
3) Quantification: It is very important to assess the threshold regulation of GM crop or products. Quantification by Real time PCR helps to determine the quantity of GM varieties present in them.
Identifying Genetically Modified Food by labeling and coding 4
One of the most common GMO detection is by checking the label on the food products. Price look-up codes or PLU code or PLU numbers are unique identification number stickers used on the products for controlling the inventories more efficiently. The PLU code numbers helps to identify the difference between conventionally-grown, organic as well as genetically-modified (GMO).They are usually 4 or 5 digit numbers.
· Organic fruits have the number “9” prefaced to the four digits. For example, if the PLU number is 4548 for the product then it would have 94548.
· Products which are genetically modified (GE or GMO) have an “8” prefaced to the four-digit code. For example, if the PLU number is 4548 for the product then it would have 94548.
Figure 2: Know your labels 13
Methods for detecting GM crops and products 5
Apart from labels, these GM foods can be identified by detecting molecule of DNA, RNA or protein. They are performed by DNA-based and Protein-based or trait-based methods.
Proteins are checked by ELISA (Enzyme Linked ImmunoSorbent Assay). In this method the enzymes are linked to antibodies which contain protein. They enable a colored substrate in order to detect specific protein. This detection method is less in cost than the DNA the methods; and they provide results in less time. This method cannot be used to test processed foods as the proteins are destroyed during the processing.
DNA based test methods are expensive than Protein-based methods. The testing procedure and their corresponding results may take several hours for completion. This method is done by multiplying a specific DNA with the PCR technique and uses two small pieces of synthetic DNA (primers) for testing. The first primer DNA matches with the start and DNA coding strand to be multiplied, while the second primer DNA matches with the end and DNA non-coding strand to be multiplied. With the target sequence, these primers match and form a chain reaction. These procedures are done again and again by consecutive heating and cooling process until they are multiplied by several sequences. These fragments are then refined in a chunk of gel, colored, and can be viewed with UV light to check contamination. Regardless of the many techniques utilized for DNA investigation, PCR method has been broadly used in GMO detection/analysis. But the DNA tests methods provide very accurate results and also can test processed foods which Protein-based methods can’t do.
Benefits of GMO
Ø Herbicide tolerance – Crops can withstand herbicide applications
Ø Insect tolerance – Crops produces toxin to kill pest
Ø Temperature resistance – Crops can withstand high and cold temperatures as well as tropical wet-dry climate
Ø Improved nutrition – Crops produces a substance of nutritive value or is changed to not produce an antinutrient
Ø Disease resistant – Crops are resistant to certain disease
Ø Stress Tolerance – Crops are tolerant of stress, low nutrient levels or excess nutrients
Ø Increased Storage – Crops can be stored longer to avoid spoilage losses
Ø Medicinal uses – Crops that produce medicines or vaccines
Ø Industrial uses – Crops to make more efficient industries
Problems with GMO
Ø Environmental risks – Crops can impact soils microbial communities and soil health
Ø Risk to human health – Certain proteins may be toxic to human health and can cause allergic reaction.
Over the last 20 years, GM foods proved both positive and negative feedback from consumers. Currently, many kinds of research are continuing on GM foods in order to address the problems in poor countries like nutrients deficiency. The future of GM research focuses on plants engineering to resist drought, high salinity, nitrogen starvation, high and low temperatures areas. The current technique followed in GM is random insertion where genes are introduced into plant cells at some random locations. The researchers are working on the future techniques which will focus on the precise insertion of genes on to the plant genome. This will avoid some unknown effects on plants growth and will improve the plants nutritious content. In the future, like the GM foods there are possibilities of developing GM animals. For example, scientists have developed a DNA sequence that will protect birds from avian influenza. It is clear that GM foods are one of the possible ways for increasing productivity in agriculture and decreasing diseases that are spread from animals but at the same time, political pressure arises from anti-GM critics to stop GM foods production. 3