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For several thousand years, farmers have been altering the genetic makeup of the crops they grow. Human selection for features such as faster growth, larger seeds or sweeter fruits has dramatically changed domesticated plant species compared to their wild relatives. Remarkably, many of our modern crops were developed by people who lacked an understanding of the scientific basis of plant breeding.This is known as Plant Breeding.

Despite the lack of understanding of the basic principle of transfer of selective traits from the parent plants to the progeny, plant breeding technique was continued. It was when a biologist Gregor Mendol,

 

Despite the poor understanding of the process, plant breeding was a popular activity.It was Gregor Mendel, a botanist, who, after many years of experiments, published a paper explaining how dominant and recessive alleles could produce the traits we see and could be passed to offspring.
 

Major advances in plant breeding followed the revelation of Mendel's discovery. Breeders brought their new understanding of genetics to the traditional techniques of self-pollinating and cross-pollinating plants.

 

Corn breeders, particularly, tried numerous strategies to capitalize on the insights into heredity. Corn plants that had traditionally been allowed to cross-pollinate freely were artificially self-pollinated for generations and crossed to other self-pollinated lines in an effort to achieve a favorable combination of alleles. The corn we eat today is the result of decades of this strategy of self-pollination followed by cross-pollination to produce vigorous hybrid plants.

 

The art of recognizing valuable traits and incorporating them into future generations is very important in plant breeding. Breeders have traditionally scrutinized their fields and traveled to foreign countries searching for individual plants that exhibit desirable traits. Such traits occasionally arise spontaneously through a process called mutation, but the natural rate of mutation is too slow and unreliable to produce all the plants that breeders would like to see.
In the late 1920s, researchers discovered that they could greatly increase the number of these variations or mutations by exposing plants to X-rays. "Mutation breeding" accelerated after World War II, when the techniques of the nuclear age became widely available. Plants were exposed to gamma rays, protons, neutrons, alpha particles, and beta particles to see if these would induce useful mutations. Chemicals, too, such as sodium azide and ethyl methanesulphonate, were used to cause mutations.

Crop
Cultivar Name
Method Used to Induce Mutation
rice
Calrose 76
gamma rays
wheat
Above
sodium azide
Lewis
thermal neutrons
oats
Alamo-X
X-rays
grapefruit
Rio Red
thermal neutrons
Star Ruby
thermal neutrons
burmuda grass
Tifeagle
gamma rays
Tifgreen II
gamma rays
Tift 94
gamma rays
Tifway II
gamma rays
lettuce
Ice Cube
ethyl methane sulphonate
Mini-Green
ethyl methane sulphonate
common bean
Seafarer
X-rays
Seaway
X-rays
lilac
Prairie Petite
thermal neutrons
St. Augustine grass
TXSA 8202
gamma rays
TXSA 8212
gamma rays

 
The next stepping stone came when James Watson and Francis Crick cracked the genetic code at Cambridge in 1953, identifying the double helix structure of DNA. Since then the human engineering of genes has been a possibility.
 
Genetic modification opens up possibilities that traditional methods never could. Genes can be added, inactivated or deleted from cells... In the most revolutionary branch of genetic engineering they can be transferred from one species to another.
 
In nature, they point out, you can't cross a fish with a vegetable. Animals and plants have long been separate in evolution. But laboratory researchers have produced a "frost-resistant" tomato by splicing into its genetic code a gene that protects a flounder from the cold. Transgenic technology provides the means to make even more distant "crosses" than were previously possible. Organisms that have until now been completely outside the realm of possibility as gene donors can be used to donate desirable traits to crop plants. These organisms do not provide their complete set of genes, but rather donate only one or a few genes to the recipient plant. For example, a single insect-resistance gene from the bacterium Bacillus thuringiensis can be transferred to a corn plant to make Bt corn.

Transgenic plants were first created in the early 1980s by four groups working independently at Washington University in St. Louis, Missouri, the Rijksuniversiteit in Ghent, Belgium, Monsanto Company in St. Louis, Missouri, and the University of Wisconsin. On the same day in January 1983, the first three groups announced at a conference in Miami, Florida, that they had inserted bacterial genes into plants. The fourth group announced at a conference in Los Angeles, California, in April 1983 that they had inserted a plant gene from one species into another species.

 The Washington University group, headed by Mary-Dell Chilton, had produced cells of Nicotiana plumbaginifolia, a close relative of ordinary tobacco, that were resistant to the antibiotic kanamycin (Framond et al., 1983). Jeff Schell and Marc Van Montagu, working in Belgium, had produced tobacco plants that were resistant to kanamycin and to methotrexate, a drug used to treat cancer and rheumatoid arthritis (Schell et al., 1983). Robert Fraley, Stephen Rogers, and Robert Horsch at Monsanto had produced petunia plants that were resistant to kanamycin (Fraley et al, 1983a). The Wisconsin group, headed by John Kemp and Timothy Hall, had inserted a bean gene into a sunflower plant.

In the Nineties, biotechnology moved out of the laboratory into farms and shops, and became a boom industry. In 1990 the first GM food, a yeast, was approved in the UK; in 1992 the first food to be made from a GM ingredient Рa vegetarian cheese Рwent on sale in the UK; and three years ago supermarkets started selling GM tomato pur̩e.

The first commercially grown genetically modified food crop was a tomato created by California company in the early 1990s called the FlavrSavr, it was genetically altered so that it took longer to decompose after being picked.A variety of the tomato was used to make tomato puree that was sold in Europe in the mid-1990s, before controversy erupted over GM crops.Then in 1998, Dr Arpad Pusztai, then of the Rowett Research Institute, Aberdeen, published research suggesting that GM potatoes, modified with an insecticide gene taken from the snowdrop, were toxic to rats in feeding trails.