Wheat Breeding and Molecular Genetics: A Needle in a Haystack
Agriculture and Agri-Food Canada
Dr. Ron Knox, with a team of scientists, are working to produce new lines of wheat by using genetic markers to improve efficiency of the breeding program at the Semiarid Prairie Research Centre (SPARC) in Swift Current, Saskatchewan at Agriculture and Agri-Food Canada (AAFC).
There are 17,000,000,000 nucleotide base pairs in wheat - about 50 times the number of characters in the Encyclopedia Britannica, and five times as many base pairs as contained in the human genome.
To discover a gene, scientists look at DNA one nucleotide at a time, which requires sophisticated equipment and computer technology all working in unison. It often takes years to identify individual genes.
Through various partnerships, AAFC's collaborative approach to wheat research brings together entomologists, pathologists, wheat breeding specialists, grain quality experts and molecular biologists like Dr. Knox. Using molecular genetics allows them to adapt new wheat varieties to increasingly complex market demands and ever-changing environmental risks.
"Finding a needle in a haystack is relatively easy compared to locating a gene within a living organism."– Dr. Ron Knox, Research Scientist, Molecular Genetics
Dr. Knox and colleagues have been developing new lines of wheat with resistance to the orange wheat blossom midge cereal pest. AAFC researchers have developed the first midge-tolerant durum. This tolerance comes from a single gene, Sm1, which causes elevated levels of naturally occurring acids to be produced when midge start feeding on the durum kernels, which in turn causes the larvae to stop feeding and die. As the orange wheat blossom midge continues to make its way westward, the value of a tolerant strain of wheat is of increasing importance.
Another example of molecular biology in action: breeders were able to identify wheat lines which showed low propensity for cadmium accumulation. When export regulations were changed to address concerns about high cadmium levels in durum, Dr. Knox and his colleagues used genetic marker technology to speed up the process for development of low cadmium varieties. Collaborative work has led to the identification of a single dominant gene that reduces cadmium levels by up to half. Incorporation of this gene reduces the cadmium in durum to levels below international limits.
Scientists like Dr. Knox are also using DNA marker technology to improve varieties for resistance against diseases such as fusarium head blight, rusts and common bunt while at the same time ensuring grain quality and protein levels are maintained.
- Wheat has an extensive genome, containing five times more nucleotides than the human genome! Developing a new line of wheat requires meticulous analysis of each nucleotide, and can take years.
- Using molecular genetic techniques, Dr. Knox has developed new wheat lines which are resistant to disease and reduce wheat cadmium levels.
- Development of new wheat varieties helps the agricultural sector to adapt to environmental risks and market demands.
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