Challenges and future perspectives of transgenic crops

By Technology Times at March 26, 2011 | 5:45 am | PrintA- Reset A+

BIOTECHNOLOGY IS the use of biological sciences to develop products. Conventional plant breeding techniques, conducted since the dawn of civilization fall under biotechnology. Biotechnology generally refers to newly developed scientific methods used to create products by altering the genetic makeup of organisms and producing unique individuals or traits that are not easily obtained through conventional breeding techniques. These products are often referred to as transgenic, bioengineered, or genetically modified because they contain foreign genetic material. Agriculture is one of the first industries that is greatly affected by this new technology on both a fundamental production level and a legal level. Development of the science and methods to produce transgenic crops began around 1983 as part of a broader technological movement to modify organisms for economic, medical, military, and other general human benefits. Implications surrounding the modification of life carry significant and complex ethical issues. The capacity to produce transgenic crops causes great controversy among government agencies, business consortia, researchers, and certain nonprofit organizations. The quantifiable facts surrounding genetically modified foods seem less in dispute than the growing number of implications.

Potential Hazards

Herbicide resistance transgenes: Herbicides are chemicals used to kill plants. In several crops, weeds are closely related to those crops, preventing the use of herbicides to control them, because such herbicides will also harm the crops. Such a job is accomplished through either the development of transgenic plants or through traditional methods. Herbicide resistance genes might be transferred by out-crossing into weeds, in this way minimizing the potential development of herbicide tolerant transgenic varieties. However on the other hand, some of the advantages of such transgenic crops can not be denied that herbicide resistance can have some environment benefits such as facilitating reduced tillage methods to conserve soil moisture, water and thus promoting the use of herbicides that have low environmental impacts such as glyphosate which is less toxic and less likely to persist in the environment than the herbicides it has replaced.

Insect resistance transgenes: Transgenic plants with high levels of insect resistance can produce a number of benefits such as elimination/reduced use of pesticides, and consequently reduced apprehensions of environment, water and food chain pollution caused by the wide spread use of insecticides. Bt toxins are of particular importance in this regard as they have very low mammalian toxicity and highly effective against major insect pests in crop plants. However, the sustainability of resistance has been raised a problem as a result of increased resistance of transgenic plants. With the continuous and long term use of transgenic for insect resistance, the development of cross resistance is not far away. To combat with this problem, various strategies have been proposed to prevent or at least delay the development of resistance to transgenic plants. This problem can be solved by rotating Bt-crops with non transgenic plants, particularly if resistance is not stable in the insect population. With spatial refuges, part of field is set aside for non transgenic plants. This activity allows resistant insects that have survived on the transgenic plants to mate with the non-selected sensitive insects from the non transgenic plants and in this way, prevents the rise of a population that is homozygous for a recessive or semi-dominant resistance allele.

Use of Selectable Marker Genes: Plant transformation is based on the ability to integrate foreign DNA into host plant genomes. Presently, low transformation efficiency of many crops necessitates the use of selectable markers to identify transgenic plants. These dominant genes confer resistance to an antibiotic or herbicide that kills non-transformed cells. Thus, single cells with an integrated transgene within a bulk of non-transformed cells can often be identified. During recent years concerns were raised-mainly by the environmentalist and consumer organizations that the existing of such genes as for antibiotic resistance within the environment or the food supply might be an unpredictable hazard to the ecosystem. Problematic’ selectable marker genes can be avoided by: Totally avoiding the use of selectable marker genes; use of marker genes (‘screenable markers’) that have potentially no harmful biological activities; co-transformation of two transgenes, one carrying the desired trait and the other the selection marker, followed by the segregation of the two; excision of selectable marker gene out of the integrated transgene after successful selection using site specific recombination or transposon, and the use of tissue specific promoters that are only active during a particular stage of development.

Future of Transgenic Crops:

History teaches that people embrace most technologies once they are convinced that they are generally safe. The examples are numerous: automobiles, airplanes, fluoridated water, microwave ovens, and cell phones have all been disputed as unsafe. As time has passed and people became more familiar with the technologies, along with their risks and benefits, the technologies have been widely adopted. In fact, other biotechnologies, such as the overproduction of pharmaceuticals in microbes are widely adopted because of their undeniable benefits. No doubt the safety and benefits of transgenic plants will prevail in the greater public’s eyes as trillions of transgenic plants are grown every year without harm, and new applications such as plant-derived edible vaccines come to market. We predict widespread acceptance of transgenic plant technology in the next 20 years. That is, we predict that this mode of plant improvement will be accepted just as travel by automobile is accepted.

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