BIOTECHNOLOGY IN AGRICULTURAL DEVELOPMENT

Abstract

About four century ago, the world was preoccupied with an impending food crisis. The situation was particularly menacing in more populous regions where mas starvation was predicted on unprecedented sclae. But a few far sighted scientists set out to tackle the problem of increasing food production by application of science of genetics, and were successful in development of miracle seed of world's most important food crops-wheat and rice. Food production, therefore, increased apace which resulting into 'Green Revolution' and the impending crisis was averted or rather, delayed. Today there are growing indications that food production is oince again struggling to keep pace with a relentlessly expanding population and is, therefore, a serious concern for food security especially of developing countries including that of India. The technologies that underpinned the Green Revolution, though still contributing to food production yet, appear to be inadequate to meet the challenges that lie ahead. The expanding population has already taken an additional and serious toll on the natural resources.

While solutions to many of these problems are to be found in the applications of wise policies and the allocation of additional resources towards development, new technologies undoubtedly also have major part to play. Just as the green revolution had its origins in science and technology, and particularly in the wscience of genetics. So the application of new biotechnological methods could lead to a new revolution -the Gene Revoluation. Plant genetic engineering took birth in the mid eighties when, for the first time, plants were successfully engineered for improved resistance to virus, herbicide and insect. With the widespread application of gene technology, it seems imperative that new technologies will not only help in enhance the crop productivity but also ensure protection against loss of potential productivity due to environmental vagaries. Plant genetic engineering could also be effectively utilized to export some of the untapped potential of natural resources to increase the harvestable crop yield. It is expected that agriculture in 21st century will include significant proportion of transgenic plants and, therefore, may be called transgenic era of agriculture.

1. Introduction

We are at the threshold of 21st century, where great challenges on three fronts namely, production, pollution and population are awaiting the developing countries. Moreover, in the era of privatization, globalization and liaberalization, there is heavy international competition within as well as between the countries on all fronts including the agriculture. The present scenario indicates that there would be "survival of the fittest". Needless to mention that by 2000 AD our population will be around one billion the priority is clear-cut before us. We have to climb upward to achieve higher and higher production to ensure that every mouth of our ever increasing population has enough to eat. The quest for agriculturists for greater productivity and improvement of existing cultivars with bettwe quality food continues with great vigour and spirit. The conventional methods of plant breeding and traditional agricultural practices have done a tremendous job and contributed to a great deal towards the above goal. However, in view of the acuteness of the problem and renewed fears regarding the availability of the proper and enough food, these methods alone are not sufficient to meet the situation. Although, the FAO believes that food production will continue to increase for the next 20 to 25 years at the same rate as experienced during the past 30 years to meet the futuristic demand. The worldwatch Institute has, however, reported that this rate may not be sustainable. Moreover, they believe that science and technology can no longer ensure the onward march of achieving higher and higher yields. In addition we are also subjected to an almost daily litany of doom and despair as a result of global warming, depletion of ozone layer, oil and water running out and so on. The next century centainly packed with trouble if the meteor does not get us first, then we will gradually either be roasted, frozen or desiccated, and to make doubly sure, shall centainly be starved as well.

It seems that if we have to stand any chance whatsoever in the next century, our capacity to adopt the living resources will be extremely important for our survival. Because of changes in the environment and depleting energy resources, this capacity to adapt will be every bit as important to those areas of the world which are blessed wtih over-production like Europe today. Accellerated adaptation through genetic change is, of course, one of the important means by which plant breeders have achieved their aims in the past. Today the new techniques of biotechnology in general and genetic engineering in particular may offer to the plant breeders and agriculturistrs the chance of speeding up adaption to an extent hitherto considered impossible. This new power will undoubtedly bring risks but it could also be the only chance we have for escaping the dangers ahead.

Biotechnology being a multidisciplinary subject requires coordinated efforts and expertise of scientists with different backgrounds to put together in order to achieve success. It may be defined as may technique that uses living organisms, or parts of organisms to make or modify products, to improve plants or animals or to develop micro-organism for specific uses. It includes well established technologies such as those used in breeding, plant propagation and conventional animal vaccine productions. Modern biotechnology encompasses the more recently developed techniques involving the use of recombinant DNA technology, monoclonal antib odies and new techniques of cell culture. Recent development in biotechnology have made it possible to move genes from microbes, plants and animal species i nto plants of interest. Biotechnology helps in the commercial utilization of gene and other things for the benefit of human kind. Howver, destruction of ecosystems has been a major concern of biotechnology.

Developing countries are naturally attracted to the potential applications of biotechnological research in solving problems of hunger, energy supply and improving the quality of life. The priorities of different countries however very widely, In this context, the National Biotechnology Board of India has chosen genetic engineering, photosynthesis, tissue culture, enzyme engineering, alcohol fermentation and immuno-technology as areas of immediate interest.

2. Application of cell biotechnology

Cell biotechnology or plant tissue culture is an enabliing technology from which many novel tools have been developed to assist plant breeders. These tools can be used to increased the efficiency of the breeding process, to improve the accessibility of existing germplasm and to create new variation for crop improvement. They include micropropagation, another culture, in vitro selection, embryo rescue, somaclonal variation, somatic bybridization and transformation. Of these somaclonal variation occupies a somewhat unique position, because it has both the advantages and disadvantages of tissue culture systems.

Somaclonal variation was first defined as such by Larkin and Scowcroft who reviewed the subject in 1981 and were amongh several authors at that time to draw attention to its potential use for crop improvement (Larkin and Scowcroft, 1981). An extensive number of reports soon followed in a whole range of species, indicating that somaclonal variation was widespread, and therefore, ostensibly accessible to all plant breeders (Karp, 1991)

The Utilization of new genetic variability has become one of the major objectives of tissue culture, The assembly of genetic variability is vital for improvement of crop plants. Somaclones for the resistance of downy mildew. Fiji disease and eye spot disease were identifies. Application of somaclonal variation in crop improvement can produce increased yield and resistance to biotic as well as abiotic astresses. Some of the crops where somaclones were produced are rice, wheat, maize, tomato, geranium, sweet pototo, sugarcane, rice, celery and brown mustard (Table 1). Our country research efforts have developed a variety called 'Pusa Jaikisan' in brown mustard evolved by somaclonal variation.

Crop	Country and Institution	New trait
Geranium	Deptt. of Hort, Purdue Univ USA	Vigour and attractive flowers
Sweet potato quality of roots	North Carolina Res, Services, USA	Colour, shape and backing
Sugarcane	Sugar Research Centre, Fiji	Yield and disease resistance
Maize	Motecular Genetics, USA	Trytophan content
Tomato	DNA Pl. Tech. of New Jersey, USA	Dry matter content, Disease resistance
Rice	Plant Research Institute, Japan Unv of Agri. Sci., Godollo, Hungary	Yield Disease resistance
Celery	DNA Pl. Tech. of New Jersey, USA	Processing, Yield & efficiency
Brown musturd	ICAR, New Delhi	Yield.

Micropropagation is another technique of great significance to agriculture which is based on in vitro culture of plant cell. Each and every cell of a plant has the potency to be regenerated into complete plant by tissue culture techniques and this property oif the cell is known as totipotency. Using this technique hundreds and thousands of seedlings can be generated in a very short time, starting from a limited number of explants. This methods of multiplication has two major adantages. First is the ast multiplication of new elite cultivars. For example, after its release, a new sugarcane cultivar may take 5-10 years before sufficient planting material may be generated for wide coverage in the farmers field. But using micropropagation techniques a comparable level of multicipation may be achieved within 2 years. The second advantage is that we get disease free planting material because of the u se of aseptic conditions during tissue culture. There is also reports of rejuvenation and increased vigous following tissue culture. This can also help in rescue of important materials which are on the verge of extinction due to disease attack. For example, a rare variety of banana used for temple offering in Karnataka has been rescued through tissue culture techniques (Singh and Garg 1997).

Micropropogation of fruit and ornamental plants provides a useful avenue for the employment generation for rural youths at cottage level industries. In species like Daffodies and gladioli, microporpagation techniques are being used to speed up the release of new varieties. In strawberry, millions of plants can be produced from a single mother plant in one year.

Micropropagation work undertaken at our Defence Agricultural Research Laboratory. Pithograh was resulted into successful multiplication of strawberry, petunia, carnation and tomato hybrid. In case of strawberry a well adapted variety of hill vi., Jyolikit Setection was taken for micropropagation studies with objective to large scale produc tion of disease free propagules since this fruit plant is highly susceptible to number of fungal, bacterial and viral diseases. The result showed that inter-nodal segmetns are most suitable explant material for micropropagation under in Vitro conditon. MS formulated with 1ppm of BAP and 0.1ppm of GA3 was found optimal protocal for maximizing shoot proliferation in explant where MS media modified with 1 ppm 1AA was most suitable for early rooting in shootlets. Peat moss was found to be most suitable potting culture for hardening of tissue culture raised plants of strawberry var. Jyolikot Selection.

Micropropagation studies in Petunia Hybrida were undertaken in order to raise the plant seedlings in mass. The result showed that optimum number of shootlets could be obtained after culturing the leaf explant of size 5mm X 2.5mm in MS media supplemented with 1ppm of BAP + 0.5 ppm of IAA with an inclubation period of 34 days. Protocol standardisation revealed that MS medium supplemented with 1 ppm of IBA was suitable for an early and healthy rooting in tissue culture raised shootlets. Hardening process was most successful with high relative humidity (90-95%), Temperature 23 + 10 C and potting mixture of sand and soil in equal proportion.

Work on micropropagation of carnation was resulted into standardization of an vitro culture media for shoot and root proliferation. Protocol found most promising for shoot proliferation was MS medium supplemented with 1 ppm of BAp AND 0.1 ppm of IAA where MS medium supplemented with 1 ppm of NAA was identified to most suitable for rooting in shootlets.

Micropropagation studies were also undertaken in hybrid tomato to generate large scale seedings to fulfill the need of army personnel as well as local growers with pure and healthy planting

material. Based on the observation it iwas found that tissue culture medium comprised of MS,0.5 ppm kinetin, 0.5 ppm IAA and 0.3 ppm GA3 was most suitable for shoot growth and MS medium supplemented with ppm of IAA or MS with 1 ppm of IBA was most suitable for early and healthy rooting in the explant material. Tissue culture regenerated plantlets showed high survival under relative humidity varied from 85-95 per cent, temperature 25+20C and potting mixture sand and oak forest humus in equal ratio.

3. Application of DNA Technology

Genetic engineering opens a totally new dimension for bioprospecting. The search for new genes and their application is the primary objective of the biotech industry. Gene technology now enable humans to integrate revolutionary new properties in to cultivated plants through inter-specific or inter-generic gene transfer which was not possible through classical approach of crop improvement.

Genetic engineering is the direct introduction into a plant of an isolated or modified single gene using transformation techniques. Now it is possible to transform almost all of the plants cultivated by man. Where this has not happened, it is more to do with the insignificance of the plant in agriculture or forestry rather than a reflection of a stubborn resistance to all attempts to transform it. A couple of years ago, cereals were regarded as being recalcitrant species. This has new changed and transformation has been reported as being successful for nearly all cereal species.

4. Transgenic plants.

Transgenic is used to describe plants which have had DNA introduced into them by means other than by the transfer of DNA from a sperm cell to an egg. Development achieved through modern biotechnology in the form of transgenics have given new options of controlling isects, diseases and weed pests, while improving the overall integrity and consequences of agricultural practices. Biotechnology combined with modern crop management techniques and the responsible use of pesticides gives the best tools available to ensure healthy, high yielding crops. However, the benefit expected from the release of genetically modified organisms into environment are quite more which are seems to pay major role in bioremediation, environmental improvement, agriculture, food industry and health care (Velkov, 1996). A number of transgenic plants in various crop species covering wide range of altered characteristics have been approved for commercial cultivation.

4.1 Resistant to biotic stresses.

Damage to crops by biotic factors like isects-pests and weeds is a major limiting factor in agriculture econ omic in tropical and temperate regions of the world. Despite large scale investment in the chemical control of pests, they cause great economic loss by damaging or destroying the crops. With a tremendous development in techniques to engineer crops genetically, we now have the ability to make broader use of natural insecticides. The choice of a Bt endotoxin, as the first insecticidal protein for introduction into plants, was based on the extensive knowledge gathered about this class of crystal protein since 1902 and such a strategy has been successfully achieved. The application of glyphosate kills crop plants just as effectively as it kills weeds. The usefulness of glyphosate as a weed control agent in agriculture could be enhanced if resistance to herbicide could be selectively engineered into crop plants. Transgenics have been developed by

introducing the corresponding resistance genes from weeds and microbes into crop plants such as tabaco. In addition genes conferring resistance against herbicides, viz., Sulphobylurea, Imidazolinones, Phosphinothricin, Asulam, Bromoxynil and 2,4-D have been engineered and transgenic plants developed.

4.2 Abiotic resistance

A large area of our country is under stress conditions i.e. saling, alkaline water, cold and heat stress etc. transgenics produced from introducing mtl 1D gene from E. coli in tobacco and arabidopsis showed tolerance to high leave of NaCl. Thermoc tolerance was found in Arabidopsis plants engineered with hsf gene. It has been reported that over-experession of sac B gene from Bacillus subtillis leads to high level of fructans in tobacco cells, and this is associated with increased drought tolerance whereas chemically synthesized antifreeze protein genelala 3 leads to improved freezing tolerance of tobacco plants.

Genetic engineering for improved tolerance to abiotic stresses is, therefore, the need of the hour as the existing cultivars in most cases are capable of giving much higher biomass that what we harvest today. While it is true taht the response of plants to these stresses is multigenic, the recent success achieved in genetic engineering against excess salt, high and low temperature as well as less or excess water by altering individual gene is noteworthy.

4.3 Product Quality.

A group of scientists have reported the ethylene sysnthesis in transgenic tomato plants, using anti-sense to a gene that has been indentified as ACC oxidase. The enzyme convert ACC to ethylene. Ethylene production was inhibited by 97% with a signification reduction in over-ripening and shriveling. Flavr Savr and Endless Summer in tomato, Freedom II in squash, high lauric acid repeseed (Canola) and Round Up Ready soybean are some examples of the crops that already being commercially grown in developed countries (Gupta, 1996)

Genetic engineering of metabolic pathways of fruits and vegetables has therefore given control over post-harvest process which not only leads to improvement of quality characteristics but also enhances processability, transportability and prologation of shelf like (Chopra 1998)

In addition, engineered plants with chage fatty acid composition of edible oil, reduced antinutritional components in many food crops, production of palm oil or animal derived industrial oil into plants like Brassica are some of the good examples of novel products that can be expected from biotechnology. Significant progress has been achieved for production of biodegradable plastics derived from biomsass of genetically altered plants having gene from bacteria.

With the advancement in DNA technology and understanding the structure and function of gene and its products more and more transgenics are coming out from various research programme all over the world. However, boon of biotechnology has been confned to few developed countries and developing countries are still in vogue to harvest the benefits of modern technology. More that 48 transgenic has picked up remarkably in last couple of years. During 1986-87, 25000 field trials were conducted with transgenics of more that 60 crops in 45 countries. Sixty per cent of these trials were in first 10 years and 40% in the last two years. Area under transgenics cultivation has also increased tremendously. During 1996, the transgenic crops covered an area of 2.8 million has which increased about 4 times during 1997 and 10 times during 1998 (Table 3)

Table 3 Area of transgenic crops planted (m ha)

Country	1997	1998
USA	8.1	20.5
Argentina	1.4	4.3
Canada	1.3	2.8
Australia	0.1	0.1
Mexico	<0.1	0.1
Spain	0.0	<0.1
France	0.0	<0.1
South Africa	0.0	<0.1
Total	11.0	27.8

Source : Anne Simon Maffat (1998)

5. Conclusion

A major challenge for agriculture in the 21st centure in developing nations would be to speed up production process economically to fulfill the aspirations of huge popuulace, to achieve diversification and adding value to the primary produce so as to make agriculture enterprise farmers as well as environmental friendly. Biotechnology based advance technologies are expected to materialize many of our expectations in the coming millennium.

4.11 Viruses

To minimize the losses due to viral disease and to reduce the use of chemicals, the cross protection phenomenon of viral coat protein and movement proteins have been employed. This methid has been used to develop transgenic plants which conferred significant levels of resistance in tobacco plants to TMV or to alfa mosaic virus (AMV) using the AMV coat protein gene.

In some viruses it has been found that certain sequences termed satellite RNAs act to reduce disease symptoms in infected plants and as such it is being utilized for developing transgenic with virus resistance. Antisense RNA which binds to sense RNA and articifial ribozyme molecules which cleave specific gene transcripts were found very powerful tools for the inhibition of viral disease development. Genetic engineeringof antisense or ribozyme genes complementary to viral genes whose products are essential may prove one of the best way of viral disease control.

4.12 Insects

Transgenic crop plants that produce pesticidal proteins such as Bt toxin can offer the growers advantae of increased yields, numerous environmental benefits due to decreased use of conventional insecticidals. A transformed tobacco plants with the gene encoding the cowpea trypsin inhibito, in feeding experiments demonstrated that wxpression of the gene conferred resistance to a range of insect genera, including Heliothis, Spodoptera, Diabrotica and Tribolium the protein is not however toxic to humans.

4.13 Herbicides

The use of herbicidea has become an important feature of modern agriculture as a means of controlling weed species, however, it is economically feasible to produce specific herbicides for use with every individual crop species. A more generic approach would be to transform a range of crop plants with a gene which confers tolerance to a single non-selective herbicide,