Discussion

Chapter Five ………………………………………

Discussion

Chapter Five: Discussion

Discussion There are about 777 million people in developing countries .Over half of these people depend primarily on agriculture for their living. Furthmore because of the large population they are projected to increase their demand for cereal grains by about 80% between 1999 & 2020. According to Rosegrant et al. (1997) that over the next two decades global demand for cereals could rise by 40%. By 2020, it is expected that 67% of the world ceral consumption will occur in the developing countries. And the problem is that most of them survive on less than US $1 a day. To meet the need of this vast population, new varieties of crops introduced in Asia between the 1960s and the 1980s increased crop yields significantly, allowing agriculture to provide food and work for a growing population, and reduce poverty. However, the improvements in crop yields achieved then have now slowed. Additionally, benefits of the Green Revolution failed to reach their. All these things keeping in mind it can say that an effective technology need to be introduce there that can meet their demand for different crops effectively as well as which would be economic for them. Considering this entire requirement the technology that can meet their need is GM (genetic modification) technology. GM technology can meet their need sufficiently in a economic way. With the help of this technology it is possible to introduce different traits in a crop species which they don’t contain before. Such as herbicide resistance, stress tolerance, disease resistance, improved nutritional value, high yielding capacity. And for introducing all these traits what you need is a cloning vector, because the process of genetic modification in different crop species is mostly carried out by the help of a vector that are able to introduce the gene of interest in a crop. Different types of vector can be used for this purpose, e.g. plasmid, BAC, YAC, bacteriophage, transposon etc. Different types of plasmid are used to date they can be E.coli plasmid such as pBR322or Agrobacterium Ti plasmid .Although both the plasmid are mostly used but due to some lacking Agrobacterium Ti plasmid are preferable. They are called

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Chapter Five: Discussion nature’s smallest engineer. In Agrobacterium tumefaciens mediated gene transfer the desired gene of interest is inserted between the T-DNA borders of Ti plasmid of Agrobacterium tumefaciens and causes the transformation in plant by entering the intercellular region. Scientist continues to search for different transforming vector as with the help of Agrobacterium small amount of DNA transfer was possible. As a result they find out about the capacity of gene transfer of yeast plasmid, virus, cosmids, transposon etc.The discovery of BAC and YAC solve the problem of transferring larger DNA sequence to plant. This speeded up the technique of transformation of plant and different crop species greatly. They (cloning vector) made possible to introduce many beneficial characters to different plant and crop species. After the discovery of YAC the era of megabases cloning started. And was used for modification of different crop species, but it has some problem too, that is the formation of chimeras. Then in the early 1990s discovery of BAC occur that reduces the risk of chimera as well as transfer of large DNA segment. But beside these advantage they also has disadvantage that the efficiency of cloning a foreign gene. They are not so efficient in transferring the desired gene. That’s why for increasing the rate of transfer researcher use the bacteriophage as cloning vector. It solves the problem of failure of expression of eukaryotic genes which occur due to inability to recognize eukaryotic promoters and the absence of RNA-processing machinery in E. coli. Scientist partially overcomes these problems by the use of cDNA cloning in the expression vectors such as λgtll. Other vectors include cosmids (plasmids that contain COS site) and transposon (the jumping gene) .with the help of cosmid DNA of about 45kb can be inserted but the problem is DNA rearrangement can occur and somewhat unstable. On the other hand transposons are very new concept for using as vector. For using transposon as vector

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Chapter Five: Discussion one need another vector e.g. plasmid for carrying the transposon. So, transposons are not direct vector for transferring any DNA sequence; they are the indirect vector for transfer of DNA sequences. Beside these merits of cloning vector there are demerits too; for using these cloning vector different side effects appear after transformation, many time the inserted gene is not properly transferred to the plant, and the strain can go back to its natural state, which causes harmful effect to plant. Such as if the phage used for transformation return to its native state it can causes different disease of the plant ; the untransformed Ti plasmid of Agrobacterium can causes gall formation to plant. Another problem that arises is the concentration of the world economy to certain people, because as for development of a GM crop took lots of money and most of the developing countries cannot afford it, they will not be able to utilize the advantage of genetic engineering. On the other hand because the developed countries will have the patent right, the developing countries will have to depend on the developed countries for using them. All these concern arise the question that weather or not we should adopt the GM crop. But it is often claimed that one reason for having GM crops is that they will help to feed the world’s growing population in this century by increasing yields and fighting crop diseases. However, many people in the world are suffering from malnutrition and hunger because they cannot afford to buy food, not because it is unavailable. Complex social, political and economic forces affect how people have access to land, money and resources. It is these forces, much more than the level of food production which determine who gets to eat, and who does not. It is not just a simple case of there being more people, so more food should be grown.

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Chapter Five: Discussion There is more than enough food to feed everyone very well at the moment, yet hundreds of millions of people go hungry and nearly two billion are malnourished. For example, in 1998 it is estimated that 36 million people, including 14 million children, were hungry or on the brink of hunger in the USA29, one of the richest countries in the world. Most GM crop produced by vector technology being grown at the moment is destined for markets in rich countries. Soya and maize are used mainly for animal feed and for adding to processed food in rich countries. Such products will not help to feed the poor and hungry of the world. The majority of GM crops being grown around the world at the moment are herbicide tolerant. These crops are designed for use in intensive farming systems, with single crops in large fields requiring heavy use of chemical inputs. Many farmers in developing countries are small scale, growing many different crops and they often cannot afford the chemicals needed. Several countries that have faced serious food shortages have raised concerns about the use of GM crops in food aid. These concerns have focused on the health and environmental effects of introducing GM crops and foods during emergency situations, often in countries lacking biosafety regulations. So, from the above we see lots of problems are associated with the use of genetically modified crops.But as the technology moving very fast, with the blessings of advanced techniques of modern biotechnology or recombinant DNA technology it is possible to overcome all these problems. Any technology have disadvantage beside its advantages. Researchers always try to find out the lackings of a technology and try to solve the problem. We hope the problems that are arising during manipulation of different cloning vector for production of GM crops will be solved soon for the welfare of human being.

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