Crops: using radiation to get desirable traits
R. PRASAD
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Radiation induced mutation does not make the seeds radioactive
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IAEA has called for increased investments in mutation technique
India has already commercialised many mutant cereals, pulses and oilseed crops
A particular rice variety thrives in the saline soil conditions seen in the Mekong Delta region in Vietnam. In fact, about 30 per cent of the region’s rice-growing area is dominated by this variety.
About 10,000 hectares of Kenyan farmland has a wheat variety that is drought resistant, high yielding and disease resistant.
Nine varieties of barley are now able to grow at 5,000 metres altitude in the Andes mountains in Peru. These varieties are able to produce 50 per cent barley.
Cotton production in Pakistan has quadrupled in the last ten years. About 70 per cent of cotton grown in Punjab, Pakistan is of a particular variety.
A groundnut variety that has improved harvest rates is grown on more than 6.5 million hectares in India.
These are some of the 3,000 crop varieties of some 170 different plant species grown in nearly 100 countries. And all these varieties have been produced using radiation or chemically induced mutation. Gamma rays are used to produce the mutation.
Mutation is a natural process and occurs spontaneously in plants. That is precisely the reason why about 1.4 lakh varieties of rice with different traits are seen in nature.
By exposing the seeds to gamma rays, the radiation induced mutation only speeds up the mutant formation.
The rate at which spontaneous mutation occurs in nature is extremely low — 10{+-}{+6}. According to a paper published last year in the IANCAS Bulletin, BARC, the rate can be accelerated to 10{+-}{+3} through radiation induced mutation.
Replicating nature
“We’re not producing anything that is not produced by nature itself,” Pierre Lagoda had stated in a Food and Agriculture Organisation (FAO) press release. Mr. Lagoda is the Head of the FAO/International Atomic Energy Agency Joint Division’s Plant Breeding and Genetics Section.
In fact, producing mutant varieties is not new. It has been done since the 1920s. In India, the Department of Atomic Energy (DAE) has been using the technique to produce many cereals, pulses and oilseeds crops. It was way back in 1973 when the first mutant groundnut variety, was commercially launched in India.
The International Atomic Energy Agency (IAEA) has now called for increased investments in this technique so that varieties with desirable characteristics such as high-yielding, disease resistant and capable of growing in stressful conditions such as drought, flood and saline conditions are produced.
The international body feels that this technique, along with others, has the power to produce varieties that can help feed every individual and grow in increasingly hostile climatic conditions.
IAEA in partnership with the Food and Agriculture Organisation (FAO) has been spearheading this technique in several countries for many decades.
In induced mutation, many seeds are first exposed to radiation. “Specific mutations cannot be achieved. It is a random process,” said Dr. S.F. D’Souza, Head of Nuclear Agriculture & Biotechnology Division at BARC.
Trial and error
It is this trial and error method that makes it time consuming. Many times, the resultant mutant would have a desirable trait such as disease resistance but may not, say, be high yielding.
“So we cross the mutant with a high-yielding variety to produce a variety that has both the desirable traits,” said Dr. D’Souza.
“Gamma rays or X-rays used for producing mutant varieties cannot make the seeds/plants radioactive,” said Dr. P.C. Kesavan, Distinguished Fellow of the M.S. Swaminathan Research Foundation, Chennai.
“Unlike the recombinant DNA technique [genetic modification] that introduces a foreign gene which can cause environmental or other problems, altering or tinkering the genome [of the plant] does not cause any problem,” said Dr. Kesavan. “It [induced mutation technique] is totally safe.”
When to use
According to Dr. Kesavan, radiation induced mutation should be used only when varieties that have a particular characteristic do not exist in nature, and when conventional breeding fails as the genes that are responsible for a desirable and undesirable characteristic are closely linked.
The Chennai based M.S. Swaminathan Research Foundation (MSSRF) has been closely involved with DAE since 2004 and has been evaluating black gram and green gram varieties along with the farmers.
“All the farmers are happy with the mutant variety,” said Dr. Ajay Parida, Director of Biotechnology Division at MSSRF, Chennai. “The farmers are able to see for themselves the difference between the mutant and normal variety.”
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