Overview.
Selective breeding.
Self pollination.
Open pollination.
Hybrids seeds.
Genetically modified seeds.
Gene editing methodology.
Potential and concerns of GM food.
Genetically modified food, is grown from genetically modified seeds.
It is called GM Food in short.
Genetically modified seeds, is the seed that is derived, by modifying the DNA,
by genetic engineering.
GM food excludes those foods, which are produced by traditional farming methods.
Though these traditional methods could involve natural genetic changes,
they are not considered as genetically modified food.
Direct intervention, and editing of the DNA molecule is involved in genetically modified food.
There are several advantages of using genetically modified seeds.
There are also many concerns regarding its use.
Traditional agriculture has been in practice for more than 10000 years.
Somewhere along the line, farmers learnt to selectively breed crops.
They selected the best seeds, from their crop to plant in their next season.
This yielded in a slightly better crop, the next year.
This process was done, over and over again.
This has been happening for thousands of years.
The food that we eat today, has the collective benefit of this selective breeding.
Scientists believe that the original crops, used by the farmers, would have been just barely edible.
In selecting the seed, the farmers are actually selecting the better genes.
To that extent farmers have unknowingly influenced the genes of the food,
that we eat today.
But, this traditional farming method, is not called as GM food.
Plants reproduce by pollination.
They are multiple ways that a plant can get pollinated.
We need to understand, and differentiate these methods,
to understand pollination.
Self pollination, is the means by which plants pollinate by themselves.
In these plants, the pollen in the stamen of the flower, is transferred to the stigma.
This results in self pollination.
Soybeans, cotton are examples of plants which can self pollinate.
In open pollination, insects, birds, and wind pollinate the plants.
Open pollination may result in plants, that are naturally varied.
Farmers have been selecting seeds, that have beneficial traits.
This practice is age old, and has been going on for several millennium.
This practice has led to better and better crops.
There was till recently, a wide variety in each type of crop.
Much of the food that we eat today, has been selectively bred,
over thousands of years.
The taste and flavour that we experience in our food today,
was not present in the food of ancient farmers.
Some of the food, might have been bitter, and barely edible.
Thanks to selective breeding, we have a wide variety of delicious food.
With the advent of industrial farming, there is a practice of growing only a single variety of the food.
This is called mono culture.
The variety in a particular type of food,
like rice, wheat, apples, banana, etc, has dramatically come down.
Industrial agriculture tends to focus, on a single variety.
Many countries have lost their diversity of food, due to mono culture of food.
Hybrid seeds are produced by specific controlled cross of two parent plants.
Hybrids are randomly created in nature, in open pollinated plants.
They naturally cross pollinate with other varieties.
Hybrid plant breeders direct the process, to control the outcome.
The advantage of hybrid seeds, come from the ability, to cross genetic material,
of different but related plants.
The selected hybrids, would have some desirable traits.
A whole new world of food crops became available by means of deliberate direct hybridisation.
Apart from taste, looks, and other desirable features, hybridisation has been used for other advantages in agriculture.
For example, drought tolerant, and pest resistant hybrid crops have been produced.
One of the advantages of deliberate or designed hybrid crops,
is that by specific cross breeding of genetic material, the desired plant can be produced in one generation.
Some hybrid plants are fertile, and some are not.
Typically the commercial seed companies, cultivate two inbred varieties.
They cross them into a hybrid strain, to produce hybrid seeds.
These hybrid seeds are sold to the farmers.
One of the simplest ways to produce hybrids, can be illustrated in the case of corn.
In this method, 3 rows of father plants are sown.
This alternates with one row of mother plants.
The entire field is sown in this fashion.
The mother plants have their pollen removed.
This ensures that the pollen, will always be received from the father plant.
The mother's seeds can than be harvested.
This is known as the first generation, or F1 hybrid.
There is a major distinction between open pollinated and hybrid seeds.
If we grow out an open pollinated seed variety, and keep it well isolated,
we will get offspring very close to the parent plant.
If we purchase F1 hybrids, and save the seeds, and grow it out,
the next generation, or the F2 generation, will be a random mix,
of the parents DNA.
The offspring plants will be wildly different from the parent plants.
If we grow a F1 hybrid seed plant, and wish to grow more of the same,
in the next generation, we need to purchase the F1 hybrid seeds.
Commercial hybrid seeds, when widely used, typically replace the natural indigenous local seeds.
Indigenous seeds, would have adapted to local conditions.
They would be tolerant to the local climate, and resistant to local pathogens.
When hybrid seeds are introduced, it is possible that they unintentionally pollinate indigenous varieties.
This reduces the gene pool of indigenous varieties.
In general, this results in a reduction of genetic diversity.
This is a cause for concern.
Big seed companies, have proprietary ownership of every hybrid variety.
Because, hybrid plants will not produce uniform offspring,
farmers have to purchase new seeds, from the seed company for every crop.
The business of the seed company, is to breed and sell the seeds, to farmers.
Why do farmers have to buy, hybrid seeds every year, after every crop?
An understanding of Mendel's genetics, who help us appreciate hybrid crop behaviour.
This is discussed in the module Mendel's genetics.
When we alter the genes of one organism, in the laboratory, by editing the gene,
or by inserting genes, from another organism, it is called genetically engineered,
or modified seeds.
The organisms can be related, or non related.
Genetic engineering involving the same species, result in production of Cisgenic plants.
We now have sophisticated tools, for gene editing.
Using this we can transplant genes from an unrelated organism, to a plant.
For example, we can transplant genes, from a bacteria to a plant.
The result of such genetic engineering, is transgenic plants.
One such case, is where a gene from the bacterium Bacillus thuringiensis,
is combined with corn seeds, create what is called as Bt corn.
This can never happen in nature.
Unrelated organisms like bacteria and plants, don't interbreed.
One of the concerns about genetically modified seeds,
is that it is done, against the laws of nature.
This type of genetic modification, is called transgenic modification.
Gene transfer can also be done, within a related species.
This is also broadly, classified as genetically modified seeds.
Usually large competitions are involved in producing genetically modified seeds.
They undertake a lot of research to identify a species, with a desired trait.
For example, a bacteria was found, which was resistant to a commonly used chemical,
in agriculture called glyphosate.
The gene responsible for this resistance is then identified, in the bacteria.
A small clipping from the seed, is then analysed, to map its genes.
The same seed can be planted in the ground, to grow a plant.
Now we need to insert, the gene isolated, and clipped out from the bacteria,
into the gene of the seed.
There are more than one technology available for this.
One of them is called the gene gun.
In this technique, a metal coated with the genes, is fired into the plant tissue.
Typically, desired DNA strands, is bound to tiny particles of gold or tungsten.
These particles are accelerated to a high velocity, and shot directly into the plant cell.
It penetrates in the nucleus, and the injected DNA, combines with the plants DNA.
The disadvantage with this method, is that it can cause cellular damage.
There are some agro bacteria, which are natural plant parasites.
The bacteria induces the plant's DNA to produce sugars, and amino acids,
to feed itself.
They have the natural ability to transfer genes to a plant.
They insert their genes into a plant cell.
This property is modified and used to insert desired genes, into the target plant.
When agro bacteria infects a plant, it transfers the T-RNA, to a random site in the plant genome.
By genetic engineering scientists, remove this T-RNA, and replace it with a desired gene.
The bacterium acts like a vector, facilitating the insertion of a desired gene.
A promotor is used, to express the gene, only in specific target cells.
The pollen in the plant, can be genetically modified, to have the desired gene.
When this modified pollen, is involved in pollination, the desired gene is carried forward.
Some of the offspring will produce seedlings with the desired property.
These genetically modified plants, with a desired traits are identified.
The plants are regenerated, till a stable seed is established.
There is a certain amount of trial and error in the process.
Large seed corporations have their own farms.
The trial seeds are planted, in specific locations, using sophisticated GPS driven machinery.
Genetically modified seeds, come with detailed planting instructions.
The genetically modified seeds, or GM seeds, are sold to farmers.
Latest genetic engineering tools, like CRISPR can be used to produce genetically modified plants.
This technique is discussed in the module CRISPR.
Different GM plants will have different desirable traits.
For example, some GM plants, would be resistant to a particular pesticide.
Farmers are encouraged, to use more of the pesticide, without harming the plant.
In some cases the same company, could be selling the GM seeds and the pesticide.
This is one of the concerns expressed about GM seeds.
There are many advantages of producing GM food.
We can produce higher yielding plants.
It can produce plants with special nutritional properties.
It can produce plants with better taste, and aesthetically, pleasing varieties of food.
It can produce plants which are resistant to drought, or extreme climates.
It can produce plants which can resist weeds.
It can produce plants which can resist a particular type of pest.
Overall genetically modified food, can produce better and more food.
This increases the production of the farmer, and eventually food produced in the country, in the world.
This is projected as a method of feeding an ever growing population of the world.
A significant portion of this population, does not have enough food to eat.
Since the industriall revolution, the population of humans, has been increasing in an exponential fashion.
The population of the planet is projected to increase from the current seven billion, to about eleven billion.
Most of this increased population, will be in developing countries.
We need to produce much more food to feed this population.
GM food is projected as a means to eliminate hunger in the world.
There are many concerns in using GM food.
GM food reduces the natural genetic variety existing in the world.
Since we do not fully understand the way genetics work,
some scientists feel that it is premature to release commercial genetically modified crops.
This is specially true for transgenic crops.
They believe that GM food can be potentially harmful for human beings.
It leads to mono culture.
It leads to increased use of fertilisers.
It leads to increased use of pesticides.
Genetically modified food crops, can contaminate neighbouring crops, by cross pollination.
Increasing number of people, now prefer organic food.
Some farmers are keen to grow organic food, to cater to them.
Genetic crops can pollinate these plants, effectively disqualifying them from being organic food.
Big seed corporations control the production of genetically modified seeds.
They patent these seeds, and force the farmers to buy fresh seeds every year.
Some of them also produce the same herbicide, that the GM food is built to resist.
Some of them also produce the same pesticide, that the GM food is built to resist.
There is a general concern that large corporations, will take control of agricultural production in the world.
We need to address the concerns related to genetically modified foods,
before we can harness the full potential of GM food.