What’s more complex, a wheat field or the farmer who planted it?
To someone who studies the genetics of cells, the farmer would be far simpler to work with. The genetic material of wheat is more than five times as large as that of humans.
The map of the genes that make a living thing is called a genome.
The wheat genome is 16 billion nucleotides in size, while humans have three billion nucleotides of DNA in their genetic code. Nucleotides direct the different activities of a plant, such as growth and oil synthesis.
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Over the past two years, Sylvie Cloutier has become intimately familiar with the complex wheat genome.
The researcher from Agriculture Canada’s cereal centre in Winnipeg has cloned a gene that helps give Glenlea wheat its extra-strong qualities.
The gene is responsible for one of the proteins in Glenlea. Other scientists at the centre will put the gene back into wheat to see if it improves the dough made from the wheat. Cloutier said the protein from each gene accounts for two percent of the total protein in the plant.
Protein increased
“So if we were able to reintroduce one or two copies, we could probably increase the total protein percent by a fraction,” she said. “The more protein you have, the more money you get for your wheat.”
However, it could take years before this scientific advance leads to improved varieties for farmers.
Cloutier said cloning the gene wasn’t easy. Finding the 3,000-nucleotide gene in a sea of genetic material 16 billion nucleotides in size “is really going to pick a needle in a haystack,” she said.
“If you had no knowledge of what this gene looked like, this approach would not work.”
Fortunately, Cloutier knew what it looked like because U.S. researchers had cloned a similar gene from a winter wheat variety.
By heating and cooling the genetic material and adding enzymes in a technique called polymerase chain reaction, she was able to create more of the gene. Then, she inserted it into another piece of DNA that lives inside bacteria.
“Bacteria multiply really fast: About double every eight minutes,” Cloutier explained.
“Overnight, you can get millions of copies that you can conserve forever.”
She put the bacteria in glycerol and stores it in a freezer to keep it dormant until she wants to grow some more bacteria and extract the DNA.
Appearance a mystery
There are about 30 other protein genes she wants to clone. But unlike her work so far, she doesn’t know what they all look like.
Over the next few years, the centre will work on a library of the complex genetic material of Glenlea wheat. Cloutier will chop the 16 billion pieces into smaller chunks of DNA about 150,000 nucleotides in size, and put them into bacteria. Then, scientists can look at the smaller colonies to find the genes responsible for the proteins.
“Rather than working with the 16 billion base pair in one little pot, you deal with it in pieces, and you try to put the puzzle back together and look for those sequences you’re interested in.”
