At the onset of organized farming, farmers have practiced plant breeding and selected plants with superior traits for the propagation of a particular species. Famous plant breeder Riley,1978, defined plant breeding as the technology of developing superior crop plants for various purposes. Further on, after the re-discovery of Mendel’s law of Inheritance, genetic principles were utilized in the development and selection of superior plants. With the help of these breeding techniques researchers were able to develop numerous varieties of plants with improved yield, quality, increased resistance to pest and diseases, and several other characteristics. As the world population is increasing at an alarming rate, the food production needs to be augmented to cater to the demands of the ever-increasing population. In this scenario, it is of utmost importance to divert our attention towards developing new varieties of plants with the ability to withstand the climatic changes and ever evolving pests and diseases without compromising on the yield. The shortcomings with conventional plant breeding are that it requires a period of around 10-15 years to develop and propagate a new variety.

 

The advent of Biotechnology paved way for modern plant breeding techniques based on molecular biology to carry out genetic modifications and insert desirable traits into plants, one prominent method of plant breeding with the potential to solve food crisis is genetically engineered transgenic crops also known as, GM crops. Genetically modified crops are developed by a technique using Biotechnology that involves inserting DNA into the genome of an organism. A GM plant is developed by transferring new DNA into plant cells. The cells with the new genetic material are developed into plants that produce seeds that will inherit the new DNA; using tissue culture technique. Genetic modification of crops is preferred because it permits gene transfer across the species, genera, family and even from unrelated organisms. The desired characteristic can be obtained from an entirely different kingdom, such as a bacterium, or from a different plant species. It also eliminates the need for union of male and female gametes and enables direct transfer of genes into the recipient parent.

 

There are several applications to Transgenic technology, the most prominent examples include gene transfer for improvement in biotic and abiotic stress resistance, herbicide resistance, quality of produce, development of novel traits, etc.

 

Plant Biotechnology has played a significant role in improving resistance to herbicide, insects, diseases, salinity, adverse climatic conditions like drought and frost; superior quality of food and inducing male sterility in selected crops.

 

Herbicide resistance: The first GM characteristic widely adopted was resistance to a herbicide, called glyphosate also known as Monsanto’s Roundup in soybeans. Glyphosate is a non-selective, translocated herbicide, which would usually kill both weeds and crops. Resistance to these types of broad-spectrum herbicides means that efficient weed control is possible because the herbicide can be applied in standing crops, without damaging the crops. Another major advantage of herbicide tolerance is that farming activities can be carried out on weedy plots, as they can be managed by herbicide application, eliminating the need for ploughing, resulting in reduced soil erosion. Drawbacks for such crops is that farmers will be forced to buy proprietary herbicides that matches the herbicide tolerant crop and is counterproductive to efforts channelled with the intention to reduce the use of chemicals for farming.

 

Insect resistanceBacillus thuringiensis is a soil bacterium that produces a group of proteins known as Bt toxin, which is lethal to insect larvae affecting the digestive system of boll worms. The gene responsible for this effect is Cry-1 Ac. It isn’t harmful for beneficial insects or others animals and has acceptability in organic farming because of its safe disposition. Gene technology has played a role in developing varieties resistant to insects such as bollworm in cotton and stem borer in maize. This feat has been achieved by transferring genes for several Bt toxins into many crops by GM technology and has greatly reduced farmers dependency on harmful chemical insecticides to control pests. The extensive use of GM crops like bollworm resistant Bt cotton has caused a shift in insect pest complex in the cotton ecosystem. A surge in the population of minor pests like tobacco caterpillar and sucking pests (aphids, thrips and mealy bugs), which are not controlled by Bt cotton is detected, causing major economic loss.

 

Virus resistance: GM technology has also been used to revive to papaya industry of Hawaii. Papaya is one of the major fruit crops of Hawaii. Incidence of papaya ringspot was first detected in the 1940s and began affecting crop yields by the 1950s. By the 1990s, there was over 50% loss in crop production and the papaya ring spot virus almost destroyed Hawaii’s papaya plantations. Under such drastic circumstances, The Hawaii Department of Agriculture developed GM papaya, resistant to Papaya mosaic virus and received approval from the regulatory board, for commercial production of GM papaya in 1995. At present, GM papaya accounts for 90% of world papaya production.

 

Quality improvements in several crops has also been achieved through Genetic modification. The starch content in potato has been increased by transferring a gene from Escherichia coli, bacteria present in the human intestine. Scientists at the National Institute for Plant Genome Research (NIPGR) have developed a high protein potato containing 60% more protein than a wild type potato and increased levels of several amino acids, using Genetic modification. Another example of GM crop is Golden rice which contains high carotene and vitamin A.

 

Now that we have explored the possibilities of GM crops, let us also look into the potential risk they pose to human health and agriculture.

 

The effect of GM crops on human health and environment are undocumented. Although countries like USA and Australia have approved GM crops for human consumption. India is yet to accord approval for any Genetically modified food crop for human consumption. The only crop approved for commercial cultivation is Bt cotton, in spite of cultivating just one GM crop India ranks Fourth in terms of transgenic crop acreage.

 

Another risk while cultivating GM crops is that the continuous application of the same herbicide could lead to development of resistance in weeds against the particular herbicide. This could further aggravate the issue, leading to increased application of herbicides to control the invasive weeds to avoid crop losses. Similarly, insecticide resistant pests could also evolve, further aggravating the usage of chemical insecticides to control the resistant pest population. Genetically Modified crops could also give rise to herbicide resistant weed, if the herbicide resistant crop were to breed with weed. A possible solution to prevent herbicide or insecticide resistance due to cross breeding could be the use of “terminator seed technology”. The seeds produced by such crops wouldn’t germinate, and there would no viable offspring. This could help in combating problems caused by Cross-breeding of GM crops with wild relatives of the weed, however it might create another problem for the farmers as they would not be able to save the seeds for sowing in the next cropping season. They would be forced to buy seeds and proprietary herbicides from the companies, who might extort the farmers.

 

GM crops have the potential to contribute immensely towards food security, improve nutritional values and better rural income. It is pertinent to mention that proper monitoring and regulation are required to be in place to ensure that the superior varieties of plants developed and marketed do not exploit the farmers. GM crops can be used simultaneously with sustainable agricultural practices to augment food security.

 

--- Written by - Andrea Cheradil

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