SCI-TECH & AGRI

Beyond double helix in this millennium

Inserting Bt gene into cotton plant is one instance of gene transfer across unrelated species not possible with conventional technology.  

t gene into cotton plant is one instance of

DURING THE last century, we have witnessed remarkable advances in various disciplines of science and technology, particularly in molecular genetics. Basic genetics that started around 1900, with the rediscovery of Mendelian principles, established the principles of inheritance. Since then, there has been steady progress in understanding the genetic makeup of all living organisms. .

A major step in human control over genetic traits was ushered in the 1920s, with the discovery that ionising radiations can induce mutations . Subsequently, several physical and chemical agents, which cause alterations in genes and chromosomes, were discovered; genetic basis for commercial exploitation of hybrid vigour in crop plants was perfected. During the next two decades, techniques of tissue culture and embryo rescue were developed to obtain viable hybrids from distantly related species.

During 1940s, it became clear that the genetic material is the DNA (deoxyribonucleic acid). In 1953, Watson and Crick elucidated and proposed the double helix structure of DNA. Year 2003 marks the 50th year of discovery of DNA double helix. Many major discoveries since the elucidation of the DNA structure, have led to a clear understanding of the structural, functional and behavioural aspects of the genetic material. Complementary advances in the field of molecular biology following this discovery have provided scientists with the ability to readily move the genetic material (DNA) between close and more distantly related organisms. There are several inherent limitations in conventional breeding. The most striking differences between the new techniques of gene technology and the genetic improvement techniques that have been practised for many years in plant and animal breeding are three-fold.

Firstly, it is the capacity to transfer genes across unrelated species and to be able to modify traits in ways not possible through traditional breeding methods; second is the increased precision of introducing genes into the target organism and third is the shortening the period of time required normally in the conventional breeding programme.

1980s and 1990s have witnessed dramatic advances in our understanding of how biological organisms function at the molecular level, as well as the ability to analyse and manipulate DNA molecules.

This understanding has accelerated the Human Genome Project (HGP) in which substantial public and private resources have been invested. By early 2001, HGP published its draft reading of the all bases and location of about 30,000 genes. This has helped in the identification of more than 40 unknown disease genes, including those responsible for epilepsy, deafness and colour blindness. The human genome map has also revealed that all members of the human family have in common, nearly 99.99 per cent of their genetic information.

Genomics has emerged as the single most powerful discipline for detailed analysis of organization, expression, and interaction of an organism at the genome level. Since 2000, about 141 large scale genome sequencing projects of a number of microbes, plants, and animals are underway and several of these are expected to be completed by the year 2003. The complete sequences of Arabidopsis thaliana, rice, yeast, and Drosophila are already known and are playing a useful role in gene transfer and elucidation of evolution and gene functions.

Additionally, modern biotechnological tools can be applied to plant and animal gene pool for generating improved varieties.

New developments in biotechnology offer uncommon opportunities for conservation, sustainable use and enhancement of biological resources. The use of biotechnological interventions needs to be looked into from the point of view of increasing genetic diversity and efficiency of economically important species. These technologies need to be adopted for increasing food security, nutritional adequacy, poverty alleviation, environmental protection and sustainable agriculture. It is hoped that modern biotechnology that is judiciously blended with traditional and conventional technologies and with adequate policy supports would help transforming the green revolution into an evergreen revolution.

Although modern biotechnology has great potential for increasing food and agriculture production, there are concerns about risks posed by some aspects of this biotechnology. In the context of biodiversity and sustainable agriculture, the technology-inherent concerns are: 1) depletion of biodiversity and poor access to tailored genetic resources, 2) adverse environmental effect, and 3) negative effects on human health.

The implications of the DNA discovery have been varied and enormous, and we are still only at the beginning of the revolution that began 50 years ago. Ajay Parida