Genetically Modified Crops

Genetically Modified (GM) crops, a marvel of scientific innovation, have sparked both interest and controversy worldwide. These organisms, altered at a genetic level, have been designed to promote higher yield, greater nutritional value, and increased resistance to pests.

Yet, they are not without their potential drawbacks. Questions about their impact on the environment, biodiversity, soil health, and pollinator species such as bees and butterflies often arise.

There’s also an ongoing debate about the possible development of pest resistance to these crops. In an effort to understand GM crops more comprehensively, this article explains GM crops’ benefits, potential risks, and their overall role in future agriculture.

All organisms like plants, animals, humans, and bacteria possess DNA (Deoxyribonucleic acid).
DNA is crucial because it dictates life functions such as growth, survival, and reproduction.
A gene is a part of DNA that decides the features passed down from parents.
Organisms produced sexually get one copy of each gene from each parent.
The total DNA in an organism is its genome.
There are about 20,000 genes in the human genome.

Conventional Breeding

Conventional, or natural breeding, is an old method used to select specific traits in plants and animals.
This method started thousands of years ago, even before we understood genetics.
An example is the different breeds of dogs, each bred for particular traits.
This process involves the offspring inheriting genes from both parents, who possess the desired traits.
Over several generations, genetic changes occur and the breed acquires the desired traits.

Laboratory-based Conventional Breeding Practices

Conventional breeding practices have now embraced genetic advancements.
Techniques like marker-assisted selection are used, which ties markers to genes of preferred traits.
This method enhances accuracy in trait selection and saves time.
Mutation breeding is another lab-based technique, in use since the 1920s for plant breeding.
A mutation implies changes in genes or DNA sequences, and all organisms experience it at minimal levels.
In mutation breeding, seeds are exposed to radiation like x-rays and gamma rays, or chemicals to up the mutation rate for a desired trait.
In the 1970s, for example, US farmers sought after grapefruits with a deeper red color and sweeter taste.
Scientists used mutation breeding to achieve this, and such grapefruit varieties are now a major part of the Texas grapefruit crop.

Genetic Modification (GM)

Modern biotechnology allows us to change an organism’s gene directly. This happens by changing the organism’s DNA or adding genes from another organism.
This technique is known as genetic engineering or Genetic Modification (GM). The goal is to get certain traits, similar to traditional breeding.
A common method of genetic modification uses a gene gun. Here, heavy metal particles covered with the desired gene are shot into cells where they integrate.
Another approach involves using bacteria or viruses carrying the gene to infect target cells. In both methods, the gene’s location within the target DNA is random.
A newer, more precise method is gene editing, often using CRISPR technology. This alters a small part of a specific gene at a specific DNA location.
Examples include a gene-edited tomato that can reduce blood pressure, and gene-edited soybean oil with better nutritional quality.

Advantages Of GM Technology

GM technology is faster than traditional breeding, reducing the generations required for trait selection.
It allows for genetic alterations that might not be possible with conventional methods, such as adding genes from other organisms.

Benefits For Agricultural Plants

GM methods can increase crop yield.
They can provide resistance to pests and diseases, enhancing yield protection.
The cost of food can be reduced through GM technology.
The use of harmful pesticides can be decreased due to increased pest resistance.
The nutritional value of crops can be enhanced.
Plants can be made more tolerant to drought, reducing the consumption of groundwater.

Examples

Bt-Cotton: The Bt toxin gene from the bacterium Bacillus thuringiensis was added to cotton. This toxin kills specific pests but is harmless to humans and other animals.
Flavr Savr Tomato: A gene from an arctic fish, providing anti-freezing properties, was added to tomatoes, improving their shelf life.

GM Mustard (DMH-11)

Objective

The use of GM technology in mustard aims to enhance yields.
The goal is to cross an Indian variant, Varuna with a European line, Early Heera (EH)-2.

Problem

Mustard is self-pollinating, making cross-pollination between different variants difficult.

Solution: Barnase Gene

The gene barnase is introduced into the Varuna plant.
This makes the plant male sterile and ready for cross-pollination with EH-2.

Male Fertility Restoration: Barstar Gene

The male sterile plant can’t produce seeds.
To overcome this, the barstar gene is added to EH-2 to restore male fertility.
The new variant with both genes can self-pollinate and produce mustard seeds.

Herbicide Resistant Gene: Bar

Adding the genes is a probability game – not all plants receive the genes.
The herbicide-resistant gene, bar, is introduced along with barnase and barstar.
Plants are sprayed with herbicide, only those with the bar gene (and thus barnase and barstar) survive.

Result: DMH-11

The final seeds have the bar, barnase, and barstar genes.
These have been named Dhara Mustard Hybrid (DMH)-11.

GM Traits In Plants

Genetic modification (GM) technology brings several significant improvements to crop production. Here are some common GM traits introduced in plants:

Herbicide Tolerance (HT)

GM crops resist specific herbicides, protecting them from damage during weed control.
HT crops are corn, cotton, and soybeans.
They help reduce soil erosion. Fewer weed removal processes, such as ploughing, means less soil disturbance.
Farmers can plant these crops even in weedy fields.

Insect Resistance

Insect-resistant crops, like Bt-cotton and Bt-corn, contain an insecticidal protein.
This protein harms only specific pests feeding on them, eliminating the need for external chemical application.

Virus Resistance

Virus-resistant traits are introduced in plants that lack natural resistance.
For example, in the 1990s, papaya was genetically modified to resist the papaya ringspot virus in Hawaii.

Multi-Traits

Some crops combine traits like herbicide tolerance and insect resistance. HT-Bt cotton is one such multi-trait crop.

Additional GM Traits

Some GM traits aim at aesthetic improvements, like non-browning Arctic apples.
Others enhance nutritional quality, like Vitamin A-rich Golden Rice.

Regulatory Approaches To GM Globally

United Nations Cartagena Protocol on Biosafety (2000)

Countries who signed can make decisions to reduce potential harmful effects on biodiversity.
They can also minimize risks to human health from the import of living modified organisms.

USA

If a new variety made with gene-editing could be created via conventional methods, it doesn’t need regulatory approval.
This only applies for single modifications.
The regulatory approval focus is on the traits, not the technology used.

European Union

Risk assessment of new GM products depends on if they were developed using GM methods.
Gene-edited crops are regulated in the same way as GM crops.

Canada

All newly developed crops, whether GM or conventionally bred, undergo the same risk assessment.

Brazil

A product is classified as non-GM based on:

No foreign gene.
Presence of induced mutations achievable by lab-based conventional breeding techniques or crossing.
Presence of naturally occurring mutations.

Argentina

The key criteria for GM product regulations are:
The techniques/methods used in the process.
No foreign gene in the final product.
Presence of new combinations of genes/DNA sequences in the plant genome.
Gene-editing is considered non-GM technology and is separately regulated.

Regulatory Framework In India

Environment Protection Act, 1986: Regulation of GM Crops is primarily governed by “The Manufacture, Use, Import, Export and Storage of Hazardous Microorganisms Genetically Engineered Organisms or Cells Rules, 1989”.
Review Committee on Genetic Manipulation (RCGM): Under the Department of Biotechnology (DBT), this committee monitors various aspects of R & D projects involving GM organisms.
Genetic Engineering Appraisal Committee (GEAC): Under the Ministry of Environment, it is responsible for the assessment of proposals related to the release of GM organisms and products into the environment.
GEAC Safety Assessment tests: Molecular characterisation (study of inserted genes), food safety studies (protein analysis, toxicity and allergenicity tests) and Environmental safety studies (field trials, Biosafety Research Level trials, impact on soil, pollen flow studies). GEAC recommendations are considered by the Environment Ministry which decides on the final approval of GM organisms and products. In India, gene-edited crops are exempted from biosafety assessment and they will be released as new varieties.

GM Crops In India

Genetically modified (GM) crops have been making waves in India’s agriculture scene, with varied levels of acceptance. Let’s break down the key players and their current statuses in simple terms:

Bt-Cotton

Introduced in 2002 as the only approved GM crop for commercial cultivation.
The objective was to protect against bollworm infestations.
As of 2018-19, Bt-cotton constituted 95% of the total cotton planted in India.

Bt-Brinjal

Cleared by Genetic Engineering Appraisal Committee (GEAC) for commercial cultivation in 2009.
Faced a 10-year moratorium due to public backlash and state recommendations.
Recent developments include GEAC allowing field trials of new Bt-brinjal varieties in eight states from 2020-23, pending a no objection certificate (NOC) and confirmed availability of isolated agricultural land.

GM Mustard

GEAC approved the environmental release of GM mustard (Dhara Mustard Hybrid/DMH-11) and its parental crops in October 2022.
The crop, developed in 2002, aims to achieve higher yield than its parental lines and other available mustard varieties.
GM mustard is India’s first edible GM crop and went through GEAC regulatory testing from 2008-2016.
However, it hasn’t been released for commercial cultivation yet. The approval for environmental release is only for four years, during which it will undergo several post-environmental-release tests.
The environmental release of GM mustard is currently being challenged in the Supreme Court.

Concerns About GM Crops

Impact On Human

GM crops undergo thorough testing before entering the market. Scientific consensus suggests that GM crops are as safe as their non-GM counterparts. However, there have been instances of potential harmful effects, highlighting the need for strong regulation.
Comprehensive safety tests are a prerequisite for GM crops before market entry.
Scientists agree that GM crops on the market are currently safe to eat, similar to non-GM crops.
In Australia, an example of potential harm surfaced when toxins from beans were introduced into field peas to combat insect-related yield loss.
Animal feeding trials of these GM field peas produced negative results.
Consequently, the development of these GM field peas was halted.
These instances underscore the importance of a strong regulatory framework for GM crops.

Impact Of Herbicide-Tolerant And Pest Resistant Crops

Extensive use of Glyphosate since 1974 has led to Glyphosate-resistant weeds.
Lab experiments found Pigweed resistant to six different herbicides (though not when combined).
HT weeds like ryegrass in Australia can grow unchecked, reducing crop yield.
GM Mustard seed development introduces a herbicide-tolerant gene (bar), raising concerns around HT weeds if farmers use herbicides.
GEAC approval is only for herbicide use during hybrid seed production, not on the crop.
The barnase-barstar system has been used for HT canola hybrids production in Canada (1995), USA (2001), Japan (2001), and Australia (2002).
Biosafety assessment reports on the herbicide-tolerant bar gene suggest it is safe for human and animal consumption and poses no significant environmental risk.

Impact Of Herbicide Usage On Human Health

In 2015, the International Agency on the Research for Cancer (WHO) suggested that glyphosate, an herbicide, might cause cancer in humans.
Despite this, the Environmental Protection Agency (USA) and the European Food Safety Agency do not believe glyphosate exposure leads to cancer.
However, some studies argue that herbicides based on glyphosate should undergo more thorough toxicological tests and research during biosafety checks.
Since October 2022, India has limited the use of glyphosate, allowing only pest control operators to use it.

Impact On Soil

Herbicides typically break down quickly in soil. The speed of this process is influenced by soil temperature and moisture.
Applying herbicides correctly in terms of timing and dosage can yield effective results while minimizing soil impact.
There are cases, however, where herbicide residuals have had unwanted effects on the soil.

Pest Resistance To Herbicides

Pests can develop resistance to pest-resistant traits such as Bt toxins released by genetically modified (GM) crops.

Decrease In Genetic Diversity

GM crops could potentially reduce genetic diversity by crossbreeding with non-GM varieties and wild relatives.
This decrease in diversity can make species more vulnerable to diseases. The resulting crossbreeds may also gain undesired characteristics such as increased invasiveness.

Potential Risk To Pollinators

Some concerns exist about the potential risks GM crops pose to honeybees and other pollinators. Although no direct negative impacts have been found, there may be indirect effects due to herbicide overuse.
This could reduce the weed population, leading to less availability of pollen or nectar. The impact of GM crops on the monarch butterfly population in the USA is still up for debate among scientists.