Since the complete sequence of genome was first
reported, there has been a dramatic increase in DNA sequence information
for plants. Notably, the Synechocystis PCC 6803genome has been sequenced,
a second photosynthetic prokaryote genome is >40% complete; Arabidopsis
genome is nearly sequenced and will be complete well ahead than
the target time 2005. A comprehensive list of more than 39,000 polymorphism
has been released. Rice genome should be completed in next three
years. We are just entering into post genomics era and now the question
is : how will we make use of this wealth of sequence information?
The information has to be translated into application genomics into
nutritional genomics, in particular. The term nutritional genomics
is used to describe work at the interface of plant biochemistry,
genomics and human nutrition. Modifying the nutritional composition
of plant foods is an urgent worldwide health issue, as basic nutritional
needs for much of the world's population are still not met. Nutritional
genomics is more than biology; it is also about producing better
food and feed for our planet. The goals: science is to increase
crop productivity, improve crop quality, and maintain the environment.
Genetic improvements in crop plants beyond current capabilities
are needed to meet the growing world demand not only for more food,
but also for a greater diversity of food, higher quality food, and
safer food, produced on less land, while at the same time, conserving
soil, water, and genetic resources.
The potential applications of plant biotechnology can play a critical
role in the betterment of farming systems in the next millennium.
Plant biotechnology will facilitate the farming of crops with multiple
durable resistance to pests and diseases, particularly in the absence
of pesticides. Likewise, transgenics and marker assisted selection
may assist in the development of high yielding crops, which will
be needed to feed the world and save land for the conservation of
plant biodiversity in natural habitats. Hence, crops should be engineered
to meet the demands and needs of consumers. The genetic base of
crop production can be preserved and widened by an integration of
biotechnology tools in conventional breeding. Similarly targeting
specific genotypes to particular cropping systems may be facilitated
by understanding specific gene by environment interaction(s) with
the aid of molecular research. High quality crops with improved
nutritional and health characteristics as well as other aspects
of added value may be obtained through multidisciplinary cooperation
among plant breeders, biotechnologists and other plant scientists.
Coordinated efforts between consumers, policy makers, farmers and
researchers will be required to convert the various aspects of a
crop ideotype into components of new and improved farming systems.
The use of transgenic crops may indeed have a beneficial effect
on the environment by significantly reducing the use of agro chemicals.
Other genes for improving crop productivity and manipulating starch/protein/oil
quality and quantity, as well as resistance to stresses such as
temperature, drought, and salinity/metal toxicity, are also being
isolated and studied. Progress is being made in the use of transgenic
plants to produce therapeutic proteins and pharmaceuticals, and
even edible vaccines. Manipulation of photosynthetic efficiency
and flowering time, and source/sink relationships, could be used
in the future to increase crop yields.
The plant genomics has revolutionized agricultural research; a
series of important traits in crops of economic importance, woody
trees, horticultural, and ornamental crops can be addressed from
a general perspective using gene function analysis from model plants.
The initial phase of this revolution in agriculture has already
occurred. Large areas of genetically modified (GM) crops of soybeans,
corn, cotton, and canola have been successfully grown in the Western
Hemisphere. In the United States in 199.9, of the total of 29 million
hectares planted with soybeans, half were planted with GM herbicide
resistant seeds. When heibicide resistant seeds were used, weeds
were easily controlled, less tillage was needed, and soil erosion
was minimized. At present transgenic cotton, soybean and corn account
for 18%, 13%, and 9%, respectively, of the national acreage in the
United States, while 25% of the canola grown in Canada is transgenic.
For more than a decade, we have been involved in nutritional genomics.
One of our goals of nutritional genomics has been to create crops
that are tailored to provide better nutrition for humans and their
domestic animals. A major target has been the improvement of nutritive
value of crop plants, in particular the amino acid composition.
Towards this end, we used an amaranth seed albumin gene (AmAl) to
develop GM crops. The AmAl protein is non allergenic in nature,
rich in all essential amino acids and its composition correspond
well with the World Health Organization standards for optimum human
nutrition. Potato is the m6st important non cereal food crop and
ranks fourth in terms of total global food production. The essential
amino acids that limit the nutritive value of potato protein are
lysine, tyrosine and the sulphur amino acids methionine and cysteine.
In an attempt to improve the nutritional value of potato, the AmAl
cDNA was successfully introduced and expressed in tuber specific
and constitutive manner. There was 3.0 to 3.5-fold increase in tuber
yield in terms of fresh weight and at least 2 fold increase in tuber
number in transgenic populations. A 35 45% increase was also observed
in total protein content with broad correlation in increase in most
essential amino acids. In addition, to remove the nutritional stress
factor namely oxalic acid from some commonly used vegetables, the
coding region of OXW gene isolated from a wood rotting fungus was
cloned and over expressed in tomato plant as it has high content
of oxalic acid. Transgenic tomatoes showed stable expression of
the foreign protein and also accumulated very little oxalic acid
in comparison to wild type plants. Apart from this, the transgenic
plants were found to be resistant to infestation by Sclerotinia
(Summary by Professor Datta)