|
t_Articles
t_Articles
July 19, 2005
Plant breeders have been improving the crops
we grow and eat for thousands of years. Traditional techniques of plant breeding
involve crossing two plant varieties, each with desirable characteristics
(usually referred to as traits) and selecting the best of these crosses. The
method is time-consuming, usually taking years to create the desired variety and
sometimes never producing the desired results. Within the past few years, plant
breeders have had a powerful new addition to their tool box - modern
biotechnology. Here are some examples of plants that have been improved with
biotechnology tools. Many of these projects are spearheaded by Asian scientists
or are carried out in Asian research institutions, making these plants truly
Asian-made!
New Corn Varieties
Bt corn - Bt corn is corn that has an additional gene, taken from a
bacterium, that enables it to produce its own protection against caterpillar
pests. By growing Bt corn, farmers enjoy several benefits. First of all, they
spray a lot less pesticides, which saves money, time, and farmers handling of
them. Secondly, because Bt corn offers more immediate protection against insects
than insecticides, in many cases farmers also benefit from higher yields with Bt
corn compared to older corn varieties, and higher prices if the corn has lower
levels of insect damage and other infestations such as fungi.
There is also a human and animal health side-benefit from Bt corn: Corn damaged
by insects is often attacked by fungi, such as fuminosin, which can cause liver
and kidney damage and may be a risk factor for some cancers. The parts of the
plant that have been gnawed and therefore damaged by the insect pests are
especially vulnerable to attack. So, Bt corn which has less insect damage,
potentially has less fungal infection, and therefore lower risks of
contamination with harmful fungal toxins.
The Philippines was the first Asian country to grow Bt corn commercially.
Globally, other countries currently growing Bt corn commercially are the United
States, Canada, Spain and South Africa.
High protein corn - Corn is an important feed component for
livestock. Nutritional deficiencies often occur in animals that are fed a
high-corn diet because the protein quality of traditional corn varieties is low,
with an unbalanced amino acid (the building blocks which protein is made from)
content. For many years therefore, plant breeders have been trying to develop a
corn with better protein content but the process of improving protein quality
and quantity with conventional tools alone has been slow and has had limited
success.
Recently plant breeders have used several biotechnology tools to put genes into
corn that result in more quality-boosting amino acids in the corn kernel.
Several of these research projects have had promising results. One of these
projects was able to raise the amount of the amino acid lysine, by an average of
35% and total protein by 26%. This is a very exciting breakthrough, as higher
levels of the amino acid lysine improve the overall quality and nutritional
value of total protein enormously, and traditional corn varieties are
particularly deficient in this essential amino acid. Scientists are confident
that having found a successful method, they will be able to develop corn with
protein contents that are even higher than this in the coming years.
|
Marker-Assisted Selection Speeds Up Plant Breeding
Using biotechnology techniques like genetic markers, plant breeders have
been able to shave months, often years off the conventional breeding
process through marker assisted selection. Genetic markers enable plant
breeders to begin their selection at the cell stage by looking for the
gene responsible and checking at an early stage of cross-breeding, whether
the desired gene has been inherited by the offspring plant, instead of
having to go through the process of cross-pollination and then growing the
offspring to see if they have inherited the desired characteristics, and
if not, starting all over again... |
Oilseeds
Vitamin A mustard oil - Vitamin A is essential to healthy human
immunity (the body's ability to fight infectious disease).Vitamin A deficiency
affects growth and development in childhood; reduces immunity to diseases such
as gastrointestinal infection and measles; and in severe cases causes blindness.
Unfortunately Vitamin A deficiency affects millions of children in Asia whose
diets do not include enough Vitamin A.
Cooking oil made from mustard seeds is the second most common type of cooking
oil used in India. Plant varieties with high levels of beta-carotene, which the
human body can convert into vitamin A have been developed using biotechnology.
The high beta-carotene mustard oil is expected to be an effective vehicle to
deliver this essential vitamin to millions of people in India and to have a
significant impact on Vitamin A deficiency on the Indian Sub-continent.
Biotechnology methods have been used to increase the levels of beta-carotene in
canola crops and the oil extracted from the plants for a number of years. One
teaspoonful of high beta-carotene canola oil in the diet is enough to provide
the recommended daily intake of Vitamin A for an adult. Now a commercial
company, in collaboration with the Michigan State University, the US Agency for
International Development, and the Tata Energy Research Institute (TERI) in
India are working on applying this technology and expertise to mustard oil,
which is a close relative of canola.
"We hope that the success of this project will help alleviate Vitamin A
deficiency among our people, especially children," says Dr Vibha Dhawan, the
principal investigator for the project for TERI.
"Mustard oil would be an efficient and inexpensive vehicle for Vitamin A, as it
is already used as the main source of cooking oil in many areas of India," she
adds.
High oleic canola oil - Canola oil comes from the rapeseed plant.
The oil extracted from traditional varieties of canola has a relatively high
percentage of polyunsaturated fatty acids. Polyunsaturated fatty acids remain
very liquid at normal room temperature and also easily break down when
heated/warmed, causing the oil to turn rancid. To make the oil more solid/less
liquid and to slow the rancidity process, canola can be treated with a process
called partial hydrogenation, but this process also unfortunately produces trans
fats, which experts believe contribute to the development of heart disease.
Using marker assisted selection techniques, plant breeders have managed to
overcome these two problems, by developing canola oil which has high oleic acid
content.
Oleic acid is a monounsaturated fatty acid, and is the fatty acid thought to be
responsible for the health benefits of olive oil, such as lower heart disease
and cancer risks. Raising the oleic acid content also reduces the amount of
saturated fatty acids in canola oil - another health plus.
Lowering the levels of polyunsaturated fatty acids eliminates the need to
partially hydrogenate because the oil is less liquid and less liable to become
rancid, and thus few or no trans fatty acids are produced.
Currently, high oleic acid canola oil is being used by food manufacturers in
place of hydrogenated vegetable oils because of its superior stability. Thanks
in part to high oleic acid canola oil, many foods such as breads, cakes and even
potato chips may be just a little bit more healthful.
|
Genetic Modification Increases Plant Variety
Another biotechnology tool available to plant breeders allows them to
introduce genes directly into plants to produce a new variety with all the
desired traits. This process is called genetic modification. For the past
two decades, scientists have used the technology to develop plants that
have better agronomic characteristics, which means that they offer direct
benefits to the farmers. Examples of the types of plants bred using these
techniques are corn, soybean, cotton and canola, with inbuilt resistance
to insects and disease. These improvements bring many benefits to farmers,
such as reducing the amount of hard physical labour required to grow the
crop and simplifying weed control.
|
Rice
High iron rice - Iron deficiency is one of the most prevalent
deficiencies in the world, and affects an estimated 30% of the world's
population. Currently, iron deficiency is tackled with iron supplements and food
fortification (that is adding iron to the food during processing). However both
these methods have had only limited success in developing countries. For example
there are some technical challenges in getting the iron mix to bind to rice
grains.
Plant breeders have had some success with traditional breeding methods to
produce high-iron rice. A variety of rice developed by the International Rice
Research Institute (IRRI) in the Philippines was able to increase iron levels by
about 10%.
In addition, several projects are currently being carried out that use
biotechnology tools like genetic modification to increase the iron content in
rice. One of these iron-rich rice varieties contains a gene from a bean that
doubles the rice's iron content. This new rice variety also has another gene
that makes the iron more easily absorbed after it is digested.
Vitamin A rice - Golden Rice, the rice variety that has high
beta-carotene levels in it, has received a lot of publicity because it could
potentially alleviate blindness in children caused by a diet deficient in
Vitamin A. As regions affected by Vitamin A many deficiency also consume rice as
a staple, rice was regarded as a suitable vehicle to deliver Vitamin A to the
children.
The original Golden Rice developed by Dr Ingo Potrykus in Switzerland has often
been criticised as producing too little Vitamin A to make a difference. Now a
team in Britain has produced "Golden Rice 2," another strain of Golden Rice that
has 20 times more Vitamin A. The scientists involved in the work are optimistic
that this new strain will produce at least half of the recommended daily intake
of Vitamin A
|
Biofortification Increases Nutrient Content
Recently, scientists have applied genetic modification to human
health challenges: One of the most exciting applications of this
technology is to enable plants to produce more nutrients on their own. By
adding a gene from another plant into the target plant, scientists are
able to develop a plant that produces more of a desired nutrient. This
technique, called biofortification, has the potential to allay chronic
malnutrition among millions of Asians. This application has far-reaching
implications for Asia, where millions still suffer from micronutrient
deficiencies. |
References:
-
Mackey, M. (2002) The Application of
Biotechnology to Nutrition: An overview. Journal of the American College of
Nutrition 21(3): 157S-160S.
-
PBI Bulletin 2002 Issue 1. Diversification of
Canadian seed oils. Part 1: Adding value to the oil.
http://www.pbi.nrc.ca/en/bulletin/2002issue1/page3.htm
|
