Cultivation of food crops
began ten thousand years back when humans discovered that the cereal grains
they have been collecting from natural stands could be grown in their own
backyards. Since then, contemporary knowledge and tools have been used to
select the plant types most suited to the human needs. Selection of easily
threshing wheat, non-shattering rice, cobs of maize, and fruits with large
edible parts are some of the well-known examples. Genetic modification of crops
continues even in the most primitive tribal populations. They select the best
cobs of maize, and ears of sorghum and millets, and hang them at the entrance
of their houses. Domestication brought about large changes in morphological,
physiological and biochemical characters by indirectly selecting them, though
the process was slow. Rediscovery of the Mendel’s laws of inheritance in 1900,
and the birth of the science of Genetics, provided knowledge based plant
improvement, and the rate of change accelerated. Hybridization to combine the
desired characters from different accessions, exploitation of hybrid vigor,
development of polyploids, and amphiploids, induction of mutations, chromosomal
translocations using radiations and chemical mutagens added new tools, and
further hastened the pace of change. However, in all these methods the genetic
manipulations were made at the cell level, and selection was based on the
phenotype. In the mid 1970’s it was discovered that the isolated genetic
material (DNA) can be cut at defined sites using specific restriction enzymes,
cloned, and the desired DNA sequences (genes) can be introduced into the
resident genomes, and expressed. This process of precisely manipulating the
genetic material at molecular level is known as the recombinant DNA (r-DNA)
technology, or as genetic engineering. The new techniques also made it possible
to directly select for the presence or absence of the gene(s) and not on the
phenotype as in the past.
First such plants
expressing a bacterial antibiotic resistance gene were produced in 1983. Since
then, a large variety of plants expressing genes from microbes, reproductively
isolated plants, animals, and even human genes have been developed. Thus the
gene pool available for the improvement of crop plants has been enlarged to
include the genes available in the entire biodiversity. Further, the existing
genes can be modified at molecular level or new genes can be synthesized. Such
plants are popularly referred as Genetically Modified Organisms (GMO’s). Crop
plants developed using classical methods of selection, hybridization and
mutations are all genetically modified, and hence, the terms Genetically
Engineered Organisms (GEO’s) clearly differentiates them on the basis of the
technique used for their development.
Soon after the
development of GE plants, and the possibilities of their large-scale
cultivation, the scientific community expressed different viewpoints
illustrated by the following quotes:
represents a radical break from evolutionary history.” - Rissler and Mellon
are making an end run around nature’s restrictions, mixing genes from many
distantly related species of organisms to provide progeny that nature would
never allow” – Giampietro (1994)
“Crops modified by
molecular and cellular methods pose risk no different from those modified by
classical genetic methods for similar traits” – NRC (1989)
is nothing more than a simple extension of traditional plant breeding” -
It is pertinent to recall that:
Most people are apprehensive of things that are new, not experienced by them
earlier – the fear of the unknown.
New technologies have always been controversial – vaccination introduced by
Edward Jenner, and pasteurization of milk are the classical examples.
All technologies have some adverse effect on environment. Even food gathering,
and hunting, practiced by humans before the dawn of agriculture, was
detrimental to the environment and biodiversity.
Growing of crops, and animal husbandry was possible only after clearing the
natural vegetation from large areas of land, and consequent loss of
All technologies have certain risks, and benefits. Humans have learned to
minimize, and control risks, and to maximize the benefits.
risk, and human perception of risk varies. Most people believe that flying has
a higher risk than travelling by road, but the statistics show that
it is the other way.
Environmental Risks from GE Crops
Environmental risks perceived from large-scale cultivation of GE crops are:
Development of new, more
virulent strains of viruses on transgenic virus resistant plants.
Effect of toxic, transgenic products from insect, and pathogen resistant plants
on non-target organisms.
Overcoming the resistance
mechanism of the transgenes by insect pests leading
to more virulent insect biotypes.
Transfer of antibiotic resistance genes, used as selectable markers in the
process of developing transgenics, to other organisms.
Safety of food items
obtained from transgenic crops – allergic reactions.
Gene flow to other crop
cultivars, traditional varieties, land races, wild, weedy related species
leading to the loss of biodiversity.
Long term effects.
The possibilities of the above-mentioned risks cannot be ruled out on the basis
of scientific knowledge. The risk-benefit analyses consider the probability of
the occurrence of risk, and the overall benefits of the technology. Out of the
above, except the gene flow, the probabilities of their occurrence are
extremely low. Moreover, if any transformation events lead to such adverse
changes they will be identified in early generation testing, and during
biosafety evaluation. While the GE crops were widely accepted in US, the
environmental groups in
started determined campaigns against the GE crops. Believers in the God’s
creation of life say that “humans have no right to tinker with the genetic
material which is the creation of God”, and “GE is against nature”. These ideas
found wide support in public. At the same time green political parties gained
considerable clout in Europe and became part of the ruling coalition
Governments. Socio-political and commercial issues underlying the resistance to
GE crops in Europe
are very different. Human populations are stable or declining in many
countries, crop productivity is high with excess production of most farm
products, produced by their heavily subsidized farmers. In contrast, population
is growing in India, and most developing countries of the world, and average
purchasing capacity is low. Additional land can be brought under cultivation
only after clearing the already low forest cover, and hence, increased
production must come through enhancing the productivity of the existing
farmland. GE crops though grown in 18 countries over an area of 67.7 million ha
in 2003 is one of the most controversial, and hotly debated issue. People
opposing globalization, privatization, multinational companies and new
technologies view GE crops as a symbol of all the above, and a means of
exploiting the farmers in poor countries.
Three level of approvals is followed, first the Institutional Biosafety
Committee (IBSC) that approves and oversees the GE research within the
Institute / Company. At the second level is the Review Committee on Genetic
Manipulation (RCGM) that permits and oversees contained as well as small plot
(one acre) field experiments. The design and layout of the field experiments is
approved by RCGM that also appoints Monitoring and Evaluation Committees (MEC)
to visit each of the field experimental sites and report to RCGM. At the third
level Genetic Engineering Approval Committee (GEAC) functions under the
Ministry of Environment and Forests Large-scale field experiments, and final
approval for commercial production are authorized by the GEAC. Besides the
above, there are State Biotechnology Coordination Committees for each state,
and District Level Committees (DLC) in each district (county), mainly to ensure
implementation of the biosafety guidelines.
General Consensus Among
Some common issues in safety evaluation have emerged for which there is
widespread agreement in the scientific community. The Ecological Society of
America has also included them in their position paper on GEOs in 2004.
The environmental benefits and risks associated with GE crops should be
evaluated with appropriate baseline – GE versus conventional crop.
The risk is dependent on
the trait, and not on the method used for developing such cultivars.
combination, and transformation event, should be evaluated independently.
Leading Science Academies
of India, China, Brazil,
Mexico U. S. National Science Academy, the Royal Society, London, and the Third
World Academy of Science after considerable deliberations brought out their
common report on GE crops. Others have also considered the ethical, and
socially sensitive issues such as transfer of animal, and human genes into
plants the public acceptability for which would vary in different societies.
The food safety issues were also extensively examined among others by the
British Medical Association, their 2004 statement says that the safety concerns
for GE foods apply equally to other conventional foods.
Genes Versus Genomes
Out crossing is ubiquitous even in highly self-pollinated plants. Occasional
out crossing and consequent gene flow is a means of enlarging the genetic
diversity of the species. Out crossing between cultivars of the same species,
cultivars to wild, weedy relatives and vice versa happen all the time when they
grow nearby (Sympatric populations). It has been a matter of concern in the
seed production programs, and appropriate measures have been evolved to
minimize the pollen flow into seed production plots. GE crops do not differ
from the traditional crops in this respect. However, some environmental
scientists have projected scenarios to scare the public, even going to the
extent that GE crops will destroy biodiversity, and the land races will be lost
forever. Gene flow can only enhance biodiversity by enlarging the gene pool, it
cannot destroy it. Genomes (complete set of genes) are constantly changing even
in nature due to mutations and recombination. In the past, the whole genomes
with about 30,000 genes each, as per the recent estimates, have been introduced
as food, fruit or ornamental crops with no apparent damage to local
biodiversity. Potato, tomato, tobacco, chillies, groundnut, maize, tetraploid
cotton, soybean, rubber are introduced crops extensively grown in the country.
Similarly many introduced species of fruit and agro-forestry trees, and
ornamentals (Bougainvillea) are grown all over the country. Botanical gardens
claim with pride the new exotic species they have introduced. All such
introductions of new genomes have not caused any appreciable harm to the local
biodiversity, how the introduction of few genes can destroy biodiversity? Of
course, precautions are necessary in dealing with herbicide resistance –
natural or engineered, and other such characters for which there is no previous
experience. Identification, management and plans for mitigation of
environmental risks should be well thought out and investigated in parallel
with the development of GE crops.
GE crops, approved for cultivation by the regulatory agencies, are as safe as
any other conventionally bred cultivars for human consumption, as well as for
the environment. Occasionally they may transfer their genes into other
cultivars in the neighboring fields or wild related species through out
crossing, like other cultivars. Cross-pollination, even in highly
self-pollinated species, is part of the nature to enhance biodiversity. It
occurs in the natural stands of the ancestral species of the crops, and has
been going on between the cultivated and their related wild species since
Dr. C. R. Bhatia is
former Secretary, Department of Biotechnology, Government of India, New Delhi.
The first transgenic
plants in India
were developed at BARC.